A Systematic Review of Zoonotic Disease Prevalence in Sri Lanka (2000

Abstract

Background:

The burden of zoonotic diseases in developing countries is significantly underestimated, influenced by various factors such as misdiagnosis, underreporting, natural disasters, climate change, resource limitations, rapid unplanned urbanization, poverty, animal migration, travel, ecotourism, and the tropical environmental conditions prevalent in the region. Despite Sri Lanka's provision of a publicly funded free health care system, zoonoses still contribute significantly to the burden of communicable diseases in the country. This study serves as a timely and exhaustive systematic review of zoonoses reported over the past 22 years in Sri Lanka.

Materials and Methods:

This systematic review adhered to the guidelines provided by the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) statement. A systematic literature search was conducted between July and September 2022, utilizing the following databases and sources: Google Scholar, PubMed, Cochrane Library, Weekly Epidemiological Reports, and Rabies Statistical Bulletins published by the Ministry of Health, Sri Lanka.

Results:

From the initial database search, 1,710 articles were identified. After excluding nonzoonotic diseases, duplicated reports, inaccessible articles, and those not meeting the inclusion criteria, 570 reports were evaluated for eligibility. Of these, 91 reports were selected for data extraction, comprising 58 original research articles, 10 case reports, 16 weekly epidemiological reports, and 7 rabies statistical bulletins. Over the study period (2000–2022), 14 parasitic, 7 bacterial, and 7 viral zoonoses have been reported in Sri Lanka. Notably, leptospirosis emerged as the most reported zoonotic disease in the country.

Conclusions:

In response to these findings, we strongly recommend the implementation of a tailored, country-specific prevention and control program. To achieve this goal effectively, we emphasize the importance of adopting a country-specific “One Health” approach as a comprehensive framework for managing and controlling zoonotic diseases in Sri Lanka.

Introduction

Infectious diseases that can naturally transmit from vertebrate animals to humans are called zoonotic diseases (WHO, 2020). It has been documented that a significant portion of emerging infectious diseases, specifically 60.3%, is attributable to zoonotic pathogens, with approximately 71.8% originating in wildlife (Jones et al., 2008). These zoonotic pathogens encompass various types, including bacteria, viruses, parasites, fungi, rickettsia, chlamydia, mycoplasma, and acellular nonviral agents (Rahman et al., 2020). The routes of transmission of zoonotic diseases to humans often occur at the interface between human populations and wildlife due to livelihood activities, the need for sustenance, and cultural practices (Namusisi et al., 2021). In addition, domesticated animals can serve as conduits, bridging the gap between humans and wildlife, creating new pathways for transmission (Magouras et al., 2020).

Recent anthropogenic changes in land use, such as rapid urbanization, intensified agriculture, deforestation, and habitat fragmentation, have notably increased the transmission of zoonotic diseases (White and Razgour, 2020). Furthermore, global phenomena like climate change, animal migration, and tourism have significant impacts on the emergence and re-emergence of zoonotic diseases (Rahman et al., 2020). Factors such as limited awareness, a preference for traditional medicines, cultural practices, and community poverty contribute to the transmission of zoonoses in the Indian subcontinent (Durrance-Bagale et al., 2021). The presence of an incomplete surveillance system, failure to detect early warning signals, and inadequate communication between sectors have likely heightened South Asia’s vulnerability to zoonotic diseases (Laxminarayan et al., 2017). Consequently, zoonoses account for a substantial 26% of the infectious disease burden in low-income South Asian countries, in stark contrast to the mere 0.7% observed in high-income countries (Grace et al., 2012). Given that infectious diseases transcend human-defined geographical boundaries, close surveillance of zoonotic diseases is imperative to mitigate risks.

Sri Lanka, a developing nation in South Asia with a population of nearly 22.1 million (World Bank data, 2022), faces significant vulnerability to the emergence and transmission of zoonotic diseases for several reasons. The country boasts rich biodiversity, including diverse wildlife such as mammals, birds, reptiles, amphibians, and marine and freshwater fish species (Don Bamunusinghage et al., 2020). Tourism plays a crucial role in Sri Lanka's economy, with ecotourism, involving safaris and adventure sports, being particularly popular (Fernando et al., 2016). However, ecotourism elevates the risk of pathogen transmission from animals to humans (Chomel et al., 2007). Furthermore, in rural and estate sectors, the primary source of household income is derived from agriculture and livestock farming (Senevirathna and Dharmadasa, 2021; Prasannath, 2015). The livestock sector encompasses cattle, buffaloes, poultry, swine, goat, and sheep farming, with notable population increases in cattle and buffalo in recent years (Livestock statistical bulletin, 2020). Rural livestock keepers are at high risk of zoonotic diseases due to frequent contact with their animals, consumption of livestock products, and limited access to health care facilities (Grace et al., 2017). Moreover, Sri Lanka’s tropical environmental conditions, characterized by high humidity and heavy monsoonal rainfall, further enhance the risk of zoonotic disease transmission (Schønning et al., 2019; Allen et al., 2017). Consequently, Sri Lanka requires a coordinated surveillance and monitoring system to proactively prevent the emergence and re-emergence of zoonotic diseases.

To the best of our knowledge, an updated systematic review addressing the incidence, diagnostic approach, and burden of zoonotic diseases reported in Sri Lanka has not been published in recent years. Therefore, conducting a comprehensive study to analyze historical and current zoonotic disease trends is essential to provide the latest data, information, and knowledge necessary to prevent the emergence and re-emergence of zoonotic diseases in Sri Lanka. This study serves as a timely and exhaustive systematic review of zoonoses reported over the past 22 years in Sri Lanka.

Materials and Methods

Systematic review protocol

This systematic review adhered to the guidelines provided by the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) statement (S1 File). A systematic literature search was conducted between July and September 2022, utilizing the following databases and sources: Google Scholar (https://scholar.google.com/), PubMed (https://pubmed.ncbi.nlm.nih.gov/), and the Cochrane Library (https://www.cochranelibrary.com/). In addition, incorporated data from the weekly epidemiological reports spanning from 2007 to 2022, as issued by the Epidemiology Unit of the Ministry of Health, Sri Lanka (https://www.epid.gov.lk/web/index.php?option=com_content&view=article&id=148&Itemid=449&lang=en). Furthermore, we conducted an analysis of rabies statistical bulletins published by the Public Health Veterinary Services, Ministry of Health, Sri Lanka (http://www.rabies.gov.lk/english/reports.php), covering the period from 2009 to 2022. Only reports that met the specified inclusion criteria were included in this study.

Inclusion and exclusion criteria

In this study, we included research articles, epidemiological reports, abstracts of proceedings, and case reports related to zoonotic diseases in humans in Sri Lanka, reported between 2000 and 2022. Zoonotic diseases were defined based on their recognition by the World Health Organization (WHO) (https://www.who.int/) and the Centers for Disease Control and Prevention (CDC) (https://www.cdc.gov/), or as documented in peer-reviewed journals. We limited our review to articles written in English.

Exclusions comprised overlapping or duplicate data, zoonotic diseases reported outside Sri Lanka, studies concerning frequently occurring zoonotic diseases where sufficient data were available, reports related to awareness and knowledge about zoonotic diseases, and studies with inadequate planning and insufficient information, as well as reports concerning nonzoonotic species or species that have evolved from original zoonotic sources and currently infect only animals or humans.

Search strategy

Initially, we identified 49 diseases as potential zoonoses that could be found in Sri Lanka based on information available from WHO and CDC websites, as well as published research and review articles in peer-reviewed journals. The names of zoonotic diseases and/or their causative agents were employed as search terms in web search engines. Search queries followed this order and utilized Boolean operators: Sri Lanka AND “Zoonotic disease” OR “Zoonosis,” Sri Lanka AND “disease name” OR “causative agent.”

Selection of studies and data extraction

Titles that aligned with the inclusion criteria were selected for article assessment. Four independent reviewers analyzed the chosen publications, evaluating criteria such as ethical and scientific study design, details regarding the study population, and the disease-causing organism. Extracted data were recorded in an Excel worksheet, covering aspects such as disease name, disease category based on etiologic agent, identified causative agent, source of test samples, number of subjects, type of sample collected, reported period, diagnostic techniques used, and significant study outcomes. The tabulated data were manually analyzed, and the results were synthesized into figures (graphs and maps) and tables. The complete search strategies, along with the report selection procedure, are illustrated in Figure 1.

FIG. 1.

PRISMA flowchart describing the strategy followed to search and select the research articles and reviews for the results synthesis.

Results

Database search and selection process

The initial database search yielded a total of 1,710 articles. To ensure the quality and relevance of the selected articles, a rigorous manual screening process was conducted. During this manual screening, 198 duplicated records were identified and excluded. In addition, 709 reports focusing on nonzoonotic diseases were removed from consideration, along with 206 reports that did not meet the predefined inclusion criteria. Furthermore, 27 reports were deemed inaccessible and were also excluded from the study. Duplicated reports were identified based on matching criteria, including title, author(s), publication year, volume, issue number, and page number(s).

Following the manual screening process, 570 reports were assessed for eligibility. Out of these, 91 reports were selected for data extraction, as illustrated in Figure 1. The final selection encompassed a diverse range of sources, including 58 original research articles, 10 case reports, 16 weekly epidemiological reports, and 7 rabies statistical bulletins.

Distribution of selected studies

The selected studies provided comprehensive coverage of zoonotic diseases, including bacterial, viral, and parasitic zoonoses. Within this set of articles and case reports, 16 articles reported findings related to 7 bacterial zoonotic diseases, and 11 articles related to 7 viral zoonotic diseases. In addition, 28 articles examined various aspects of 14 parasitic zoonotic diseases.

The studies were further categorized based on their focus on humans or animals, resulting in 41 studies dedicated to zoonoses in humans and 14 studies centered on zoonotic diseases in animals. Table 1 provides a comprehensive overview of the included articles and case reports.

Table 1.

Details of Studies on Zoonotic Diseases in Sri Lanka (2000–2022)

Disease	Identified causative agent(s)	Source of test samples	No of subjects/ patients and sample type	Reported or published period	Diagnosis techniques applied	Major outcomes of the study	Reference
Bacterial zoonoses
Leptospirosis	Leptospira interrogans L. weilii	Humans	401, blood samples	2008–2009	IgM ELISA, MAT, PCR and sequencing	Highest titer of patient serum sample reacted with serovars pyrogens (28.7%)	Agampodi et al., 2011
Leptospirosis	L. interrogans L. borgpetersenii L. kirschneri	Humans	168, blood samples	2013–2014	IgM immunochromatographic assay, MAT, PCR-RFLP and sequencing	L. interrogans is the most common species among the tested samples	Bandara et al., 2015
Leptospirosis	L. interrogans L. borgpetersenii L. kirschneri L. weilii	Humans	1192, blood samples	2016–2019	qPCR and sequencing	The first evidence of serogroups celledoni and betaviae in Sri Lanka	Jayasundara et al., 2021
Leptospirosis	Leptospira sp.	Humans	1734, blood and urine samples	2016–2019	qPCR, acute sample microscopic agglutination test and paired serum sample MAT	34.1% of cases were confirmed as leptospirosis and 17.1% as “probable” leptospirosis cases	Warnasekara et al., 2022
Leptospirosis	L. interrogans L. borgpetersenii L. kirschneri	Cattle	164, kidney samples	2010	Nested PCR and sequencing	Cattle act as a reservoir of human leptospirosis	Gamage et al., 2014
Leptospirosis	Leptospira sp.	Small mammals	131, blood, urine and kidney samples	Published in 2016	qPCR	Of the 131 subjects, 14.5% was positive for Leptospira	Yathramullage and Meegaskumbura, 2016
Scrub typhus	Orientia tsutsugamushi	Humans	64, serum samples	2012–2013	IgM and IgG ELISA	84.4% of the patients presenting with clinical features of rickettsioses were seropositive for scrub typhus	Pradeepan et al., 2014
Scrub typhus and spotted fever	O. tsutsugamushi, Rickettsia conorii R. typhi	Humans	31, blood samples	2002–2003	Indirect fluorescent antibody assays	94% of patients were confirmed, presumptive, or exposed cases of acute rickettsial infections	Premaratna et al., 2008
Scrub typhus and spotted fever	O. tsutsugamushi, R. conorii, and R. typhi	Humans	371 blood samples	2002–2007	Indirect immunofluorescent antibody assay with species-specific antibodies	40.9% of Rickettsia conorii and 5.7% of Orientia tsutsugamushi, with mixed antibody reactivity to more than one antigen in 53.3% of cases, including Rickettsia typhi in 25.7% were detected	Kularatne et al., 2013
Scrub typhus and spotted fever	O. tsutsugamushi, R. conorii, and R. typhi	Dogs	123, blood samples	2010	Indirect immunofluorescence antibody test	49% dogs were found to have antibodies against the rickettsial agents	Nanayakkara et al., 2013
Spotted fever	Rickettsia sp.	Ticks	30,933 ticks	2009–2011	Nested PCR	Rickettsial infections were found in four tick species Amblyomma testudinarium, Rhipicephalus sanguineus, Amblyomma clypeolatum, and Amblyomma javanense	Liyanaarachchi et al., 2015
Brucellosis	Brucella abortus B. melitensis	Humans	1294, blood samples	2014–2015	SAT	The overall seroprevalence for Brucella infection was 8.4% for participants screened	Karunanayake et al., 2019
Q fever	Coxiella burnetii	Humans	178, serum samples	2009	Immunofluorescence	3 (1.6%) patients had acute Q fever	Angelakis et al., 2012
Shigella diarrhea	Shigella flexneri II S. sonnei	Humans	346, stool samples	2014–2015	Slide agglutination using commercial antisera and antibiotic sensitivity tests	S. flexneri II was identified in 14 patients and Shigella sonnei from one patient	Sathiadas et al., 2016
Campylobacter sp. infection	Campylobacter jejuni	Toque macaques	58, fecal samples	2015	Matrix-associated laser desorption/ionization-time of flight mass spectrometry and pulsed field gel electrophoresis	17% of samples screened were positive for C. jejuni.	Tegner et al., 2019
Viral zoonoses
Hantavirus infection	Hantavirus (more similar to Thailand virus)	Humans	105, serum samples from patients with febrile disease of unknown origins	2008	ELISA, PCR, MAT and indirect immunofluorescence antibody assay	Serotyping ELISA reported eight patient samples showing high optical density values for Thailand virus	Gamage et al., 2011
Hantavirus infection	Hantavirus	Humans	72, blood samples	2013–2015, 2016–2018	Immunofluorescence assay	40.28% of patients were positive for hantavirus IgM	Muthugala et al., 2021
Hantavirus infection	Hantavirus	Humans	Blood samples from 179 CKDu patients and 97 controls	Published in 2020	Indirect ELISA	27.9% of CKDu patients were found positive for IgG antibodies to Puumala, Hantaan	Sunil-Chandra et al., 2020
Hantavirus infection	Thailand orthohantavirus (THAIV) Thailand orthohantavirus-related orthohantavirus (TRHV)	Rodents	116, blood samples and kidney tissues	2016 and 2017	Indirect immunofluorescent antibody assay, PCR and sequencing	Hantavirus present in rodents in Sri Lanka is related to THAIV or TRHV	Lokupathirage et al., 2019
Human rabies	Rabies virus	Humans	79, clinically diagnosed brain samples	2008–2010	Fluorescence antibody test, RNA extraction, cDNA synthesis, PCR and sequencing	77 of the 79 samples were diagnosed as rabies-positive with fluorescence antibody test and/ or nested PCR	Matsumoto et al., 2013
Canine rabies	Rabies virus	Dogs	57 formalin fixed paraffin embedded brain tissues	2007–2011	Stained with hematoxylin and eosin or labeled immunohistochemically for viral antigen, RNA extraction and reverse transcription, HnRT-PCR, and RT-PCR	Rabies was confirmed in 93% of cases by immunohistochemical labeling and confirmed by PCR	Beck et al., 2017
Influenza	Influenza A (H3N2)	Humans	30, serum samples and nasopharyngeal aspirates	Published in 2001	Direct fluorescent testing and hemagglutination inhibition tests	The causative agent was identified as influenza A H3N2	Lamabadusuriya, 2001
Influenza	Influenza A (H3N2)	Humans	300, nasopharyngeal aspirates	2003–2004	Immunofluorescence assay, hemagglutination inhibition test, RT-PCR and sequencing	Influenza A H3N2 Panama/2000/99-like viruses were isolated in 8% and influenza B/Sichuan/379/99-like viruses in 3% of samples	Perera et al., 2010
Influenza	Influenza A (H3N2) and A (H1N1)	Swine	300 tracheal and nasal swabs and serum samples; 2710 tracheal and nasal swabs and serum samples	2004–2005 2009–2012	Hemagglutination inhibition testing, neuraminidase inhibition testing, cDNA synthesis, PCR, genome sequencing, and one-step quantitative real-time reverse transcription	The identified human-like influenza (H3N2) virus was widespread in the swine population in 2004–2005	Perera et al., 2013
Japanese encephalitis	Japanese encephalitis virus	Humans	1689, questionnaires and sera samples	2013–2014	Japanese encephalitis IgG ELISA	Adults and in children who were hospitalized due to dengue were more likely to be seropositive for Japanese encephalitis virus antibodies	Jeewandara et al., 2015
West Nile virus infection	West Nile virus	Humans	108, sera and cerebrospinal fluid (CSF) samples	Published in 2015	ELISA and plaque reduction neutralization test	Three of the 108 patients had West Nile virus IgM antibody in serum and one had antibody in the CSF	Lohitharajah et al., 2015
Parasitic zoonoses
Protozoa
Toxoplasmosis	Toxoplasma gondii	Humans	293, blood samples	2014	OnSite Toxo IgG/IgM Rapid Test-Dip Strip®	The prevalence of anti-Toxoplasma gondii IgG and IgM antibodies was 12.3% and zero, respectively	Chandrasena et al., 2016
Toxoplasmosis	T. gondii	Humans	536, blood samples	2010–2013	ELISA	Seroprevalence of T. gondii present among the study population is 29.9%	Iddawela et al., 2017
Toxoplasmosis	T. gondii	Humans	200, serum samples	2009–2010	OnSite Toxo IgG/IgM Rapid Test-Dip Strip®	22.5% of subjects were seropositive for anti-T. gondii IgG antibodies	Subasinghe et al., 2011
Toxoplasmosis	T. gondii	Cats	86, serum samples	2008	MAT	Antibodies were found in 30.2% of study population and the seropositivity increased with age	Kulasena et al., 2011
Toxoplasmosis	T. gondii	Dogs	86, blood and tissue samples	2006	MAT, bioassays and PCR-RFLP	Antibodies to T. gondii were found in 67.4% of study population	Dubey et al., 2007
Giardiasis	Giardia intestinalis	Humans	489, fecal samples	2013–2014	Direct wet smears, formal-ether concentration technique, and Ziehl-Neelsen staining	0.2% infection of Giardia intestinalis in children was detected	Galgamuwa et al., 2016
Giardiasis	G. duodenalis	Calves and buffaloes	637, fecal samples	2013	PCR-based mutation scanning-targeted sequencing	G. duodenalis assemblages A and E were detected in the samples from cattle and water buffaloes	Abeywardena et al., 2014
Malaria	P. knowlesi	Humans	2.2 million blood smear tests	2015–2016	Microscopic observation with Giemsa staining and PCR when necessary	One case of P. knowlesi confirmed	Dharmawardena et al., 2017
Cryptosporidiosis	Cryptosporidium parvum	Humans	138, fecal samples	2011–2013	Modified Ziehl-Neelsen staining, DNA extraction and PCR	Cryptosporidium is one of the etiological agents responsible for childhood watery diarrhea in Sri Lanka	Sirisena et al., 2014
Cryptosporidiosis	C. parvum	Human	Case report, stool sample	Published in 2020	PCR using species-specific primers	Prevalence of Cryptosporidium infection among children with diarrhea was 5.7%.	Weerasooriya et al., 2020
Cryptosporidiosis	Cryptosporidium sp.	Monkeys	125, fecal smaples	2001	Modified Ziehl-Neelsen staining, DNA extraction, and nested PCR	The prevalence of infection was significantly higher among exposed macaques (72%) than among those from clean habitats (22%)	Ekanayake et al., 2006
Nematodes
Lymphatic filariasis	Brugia malayi	Humans	250, blood samples	2009–2010 and 2013–2015	Thick night blood smears and dipstick tests to test antibodies to B. malayi	Re-emergence of brugian filariasisis (antibody rate, 1.6%; one microfilaria positive) is a cause for concern	Chandrasena et al., 2016
Filariasis	Dirofilaria repens B. malayi	Cats and dogs	250 and 134 blood samples from dogs and cats, respectively	2016–2017	Giemsa-stained thick blood smears and PCR	D. repens infection: dogs, 54.4% and cats, 34.3% and Brugia spp. Infection: dogs, 51.6% and cats, 30.6%	Mallawarachchi et al., 2018a
Brugian filariasis	B. malayi	Humans	991, blood samples	2016–2017	Brugia rapid test	The periodicity pattern of the re-emergent Brugia spp. suggests a zoonotic origin	Mallawarachchi et al., 2018b
Ocular dirofilariasis	D. repens	Humans	31 worm specimens extracted from ocular nodules	2006–2014	Morphological identification and PCR	High incidence of ocular dirofilariasis	Iddawela et al., 2015
Oral subcutaneous Dirofilariasis	D. repens	Humans	Two case reports	2011–2014	Ultrasonograph and histopathological evaluation		Jayasinghe et al., 2015
Canine dirofilariasis	D. repens	Dogs	162 blood samples from dogs	Published in 2022	Direct smear with Giemsa stain and PCR	D. repens was detected in 58.6% of the study population	Dasanayake et al., 2022
Dirofilariasis in dogs and cats	D. repens	Dogs and cats	Blood samples from 250 dogs and 134 cats	2016–2017	Giemsa staining and PCR	Infection rate was 54.4% for dogs and 34.3% for cats were	Mallawarachchi et al., 2018a
Toxocariasis	Toxocara canis	Humans	1020, blood samples	Published in 2003	ELISA with T. canis larval excretory-secretory antigen and double sandwich ELISA	91% of the seropositive were due to T. canis	Iddawela et al., 2003
Toxocariasis	T. canis	Dogs	50, fecal samples	2018	Sheather's sucrose flotation method, direct iodine smears and nested PCR	T. canis had the highest prevalence (28.0%) among the detected gastrointestinal parasites	Bandaranayaka et al., 2019
Angiostrongyliasis	Angiostrongylus cantonensis	Humans	Case report	2007	Fundus examination	Predilection for the eye can reflect a different Angiostrongylus strain in Sri Lanka	Ihalamulla et al., 2007
Hook worm infection	Ancylostoma ceylanicum	Humans	Case report	Published in 2020	Gastro intestinal endoscopy	The possibility of A. ceylanicum as a potential zoonotic threat in Sri Lanka	Mallawarachchi and Samarasinghe, 2020
Cestodes
Bertiella infection	Bertiella studeri	Humans	Case report, stool sample	Published in 2001	Parasitological diagnosis techniques		Karunaweera et al., 2001
Bertiella infection	B. studeri	Humans	Two stool samples (two case reports)	Published in 2006	Parasitological diagnosis techniques		Morawakkorala et al., 2006
Bertiella infection	B. studeri	Humans	Tapeworm proglottids from 24 pediatric patients	2007–2017	PCR and Sanger sequencing	ITS2 sequences showed 99.35% similarity with B. studeri	Amarasinghe et al., 2020
Subcutaneous sparganosis	Spirometra sp.	Humans	Two case reports	Published in 2001	Parasitological diagnosis techniques		Dissanaike et al., 2001
Cerebral sparganosis	Spirometra sp.	Humans	Case report	Published in 2007	Hematoxylin and eosin staining		Alibhoy et al., 2009
Hydatidosis	Hydatid cyst	Humans	Case report	2010	CT scan and histopathological analysis		Welgama et al., 2019
Hymenolepis	Hymenolepis diminuta	Humans	Case report	Published in 2014	Microscopic examination		Sinhabahu et al., 2014
Taenia taeniaeformis infection	T. taeniaeformis	Human	Case report	1998	Examination of vomitus containing the worms		Ekanayake et al., 1999

Bacterial zoonoses

Leptospirosis

Leptospirosis stands as the most prevalent bacterial zoonotic disease reported in Sri Lanka. Between January 2007 and September 2022, a total of 78,263 leptospirosis cases were reported in the country. Notably, this disease gained significant attention following the 2008 outbreak in the Central Province of Sri Lanka, which resulted in 7,406 cases and 204 deaths, with a case-fatality rate of 1.3% in the endemic districts of Kegalle, Kandy, and Matale (Agampodi et al., 2011). In 2011, approximately 6,626 cases of leptospirosis were reported, coinciding with heavy rains and floods in the first quarter of the year (Bandara et al., 2015). Interestingly, the peak incidence occurred during the paddy harvesting season (Yathramullage and Meegaskumbura, 2016). In 2020, Sri Lanka experienced its highest number of leptospirosis cases (8,579), potentially influenced by increased farming activities or reduced attention to doxycycline prophylaxis due to the COVID-19 pandemic (Niriella et al., 2021). Studies have identified four pathogenic Leptospira species as potential causes of leptospirosis in Sri Lanka, namely, L. interrogans, L. weilii, L. borgpetersenii, and L. kirschneri (Jayasundara et al., 2021). Another study found that 34.1% of patients with undifferentiated febrile and clinically suspected leptospirosis were positive for leptospirosis (Warnasekara et al., 2022). Several risk factors for leptospirosis have been identified, including floods, heavy rainfall, exposure to rodents, and specific occupational activities such as agriculture, gem mining, construction work, and sand mining (Epidemiology Unit, 2016). In addition, cattle serve as important reservoirs for human leptospirosis (Gamage et al., 2014).

Rickettsioses

Rickettsioses stands out as the second most prevalent bacterial zoonotic disease in Sri Lanka. According to the Epidemiology Unit of the Ministry of Health in Sri Lanka, there were a total of 21,840 reported cases of typhus fever in the country from 2007 to 2022, with the highest number of cases (1,788) occurring in 2016 (Fig. 2B).

FIG. 2.

Impact of paddy cultivation on leptospirosis cases reported in Sri Lanka (2007–2021). Epidemiology Unit, Ministry of Health, Sri Lanka; Department of Census and Statistics, Sri Lanka.

To review the prevalence, risk factors, and diagnosis of spotted fever and typhus fever in Sri Lanka, we selected three hospital-based studies (Pradeepan et al., 2014; Premaratna et al., 2008; Kularatne et al., 2013). Two of these studies (Kularatne et al., 2013; Premaratna et al., 2008) assessed the prevalence of rickettsioses in the Western Province and Central Hills of Sri Lanka from 2002 to 2007. These studies revealed that out of 402 patients with suspected rickettsioses, 26 were infected with scrub typhus, and 63 were infected with spotted fever group infections. The Northern region of Sri Lanka also reported a notably high prevalence of scrub typhus, with an infection rate of 84.4% among patients older than 12 years between 2012 and 2013 (Pradeepan et al., 2014). In another study involving 178 patients from Matara, the findings indicated that 25 (14%) patients had scrub typhus, 6 (3%) had SFG rickettsioses, 3 (1.6%) had murine typhus, and 3 (1.6%) were infected by Rickettsia felis (Angelakis et al., 2012).

Brucellosis

Brucellosis is a recognized endemic zoonotic disease across the Asian continent, with notable impacts on livestock productivity and human health in the region. In a study by Karunanayake et al. (2019), the seroprevalence of human brucellosis was investigated in 1,294 healthy individuals living in the Central, North-West, North-Central, and Western Provinces of Sri Lanka between 2014 and 2015. The researchers conducted Standard Tube Agglutination Tests (SAT) using Brucella abortus and B. melitensis antigens, revealing that 8.4% of the study population tested seropositive for brucellosis. In addition, livestock farmers were identified as a high-risk group for Brucella infection (Karunanayake et al., 2019).

Bovine brucellosis has been reported in three provinces in Sri Lanka, specifically, Uva, North Central, and Sabaragamuwa. The Uva Province recorded the highest disease incidence, accounting for 72.5% of the cases.

Q fever

In 2009, Angelakis et al. (2012) conducted a retrospective investigation in Matara involving 178 patients who were suspected of having rickettsioses due to the presence of an eschar or a rash. The study revealed that 3 out of these patients (1.6%) had acute Q fever (Angelakis et al., 2012). No other publication about Q fever caused by Coxiella burnetii in Sri Lanka was identified in our search.

Shigellosis, campylobacteriosis, salmonellosis, and listeriosis

Shigella sp. is a zoonotic bacterium that can be transmitted to humans through the consumption of contaminated food or water. Two common pathogenic Shigella species are S. flexneri and S. sonnei, with S. flexneri being endemic in developing countries and frequently isolated worldwide (Epidemiology Unit, 2007). A study in Jaffna, Sri Lanka, investigated the presence of S. flexneri 11 and S. sonnei in children. It was reported that out of 346 children screened, 15 were found to be infected with Shigella sp., and it was noted that these affected individuals did not have access to clean water (Sathiadas et al., 2016).

Campylobacter sp. and Salmonella sp. are two major zoonotic bacterial pathogens responsible for food-borne illnesses and deaths worldwide. Contaminated meat, dairy products, and eggs are common sources of infection (Abebe et al., 2020). In Sri Lanka, the presence of Campylobacter jejuni was confirmed in free-roaming toque macaques (Tegner et al., 2019), while Salmonella sp. was detected in broiler chicken meat (prevalence rate of 11.6%) (Jayaweera et al, 2020). In addition, Kalupahana et al. (2018) reported the detection of Campylobacter sp. in broiler chicken and suggested that the tropical climate in Sri Lanka provides favorable conditions for Campylobacter colonization in its hosts (Kalupahana et al., 2018).

Listeriosis, a rare, but severe foodborne disease caused by the bacteria Listeria monocytogenes, can survive and multiply at low temperatures typically found in refrigerators, according to the WHO. In Sri Lanka, Listeria monocytogenes was detected in raw milk and other dairy products such as ice cream, pasteurized milk, curd, cheese, and yogurt. The distribution of raw milk contamination was significant, with the highest incidence in the Kandy and Gampaha districts of Sri Lanka (Wijendra et al., 2014). Moreover, Gunasena et al. (1995) reported the presence of Listeria monocytogenes in raw chicken and vegetables, including green leaves, cabbage, and lettuce, obtained from retail shops in Gampaha, Colombo, Kiribathgoda, and Dalugama (Gunasena et al., 1995).

Several food poisoning outbreaks in Sri Lanka have been linked to the consumption of contaminated food. For instance, in 2006, a food poisoning outbreak in Biyagama affected over 200 employees of a company, and contaminated chicken meat was identified as a possible cause. However, the specific causative pathogen was not identified.

Viral zoonoses

Hantavirus infection

Hantavirus infection is recognized as an emerging zoonotic infection in Sri Lanka (Gamage et al., 2011), with black rats and lesser bandicoot rats being identified as potential reservoir animals (Lokupathirage et al., 2019). The prevalence of hantavirus infection among people in the North-Central (Muthugala et al., 2021; Sunil-Chandra et al., 2020) and Central (Gamage et al., 2011) regions of Sri Lanka has been reported. However, it is suggested that hantavirus infection may have been underreported (Gamage et al., 2011) and misdiagnosed (Ehelepola et al., 2018) in Sri Lanka due to its close clinical resemblance and epidemiological characteristics to leptospirosis.

A study conducted in Kandy, Sri Lanka, aimed to determine the prevalence of hantavirus infection among 105 suspected leptospirosis patients. The study revealed that 8 patients from the study group tested positive for hantavirus antibodies (Gamage et al., 2011). In another hospital-based study, the prevalence of hantavirus infection was investigated in 72 patients admitted to two hospitals in the North-Central Province of Sri Lanka, with symptoms resembling hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. The study reported that 40.28% of the patients screened were found to be positive for hantavirus IgM (Muthugala et al., 2021). However, the infection may have been underreported and misdiagnosed due to its clinical and epidemiological similarities to leptospirosis.

Rabies

From 2000 to 2021, Sri Lanka reported a total of 1079 human rabies cases. The highest number of human rabies cases, with 109 cases, was documented in the year 2000. Nevertheless, the annual count of human rabies cases reported has consistently decreased since 2006 (Fig. 3). In 1984, Sri Lanka declared seven districts—Kurunegala, Colombo, Kalutara, Gampaha, Galle, Hambantota, and Matara—as rabies-endemic areas.

FIG. 3.

Yearly fluctuations and geographical distribution of leptospirosis and typhus cases reported in Sri Lanka. (A) Yearly fluctuations of leptospirosis cases reported in Sri Lanka (2007–2022). (B) Yearly fluctuations of typhus fever cases reported in Sri Lanka (2007–2022). (C) Total leptospirosis cases reported by district in Sri Lanka (2007–2022). (D) Total typhus fever cases reported by district in Sri Lanka (2007–2022). Epidemiology Unit, Ministry of Health, Sri Lanka.

A significant proportion of human rabies cases in Sri Lanka were attributed to bites from stray dogs and household pets. For instance, in 2016, 20 human rabies cases were reported in the country, with ten cases resulting from stray dog bites and four from household pet bites (Epidemiology Unit, 2017). Matsumoto et al, (2013) diagnosed 79 human rabies cases between 2008 and 2010, analyzing brain samples sent to the Rabies Diagnosis and Research Laboratory in Colombo, Sri Lanka. Their findings revealed that 92.2% of patients were bitten by dogs, while 7.8% were bitten by cats (Matsumoto et al., 2013).

The prevalence of the rabies virus in dogs in Sri Lanka was assessed through 57 canine brain samples submitted for screening at the University of Peradeniya from 2007 to 2011. Among these samples, 53 were found to be positive for the rabies virus (Beck et al., 2017). Moreover, free-roaming mongooses were identified as potential reservoirs for the rabies virus in Sri Lanka (Patabendige and Wimalaratne, 2003). The Veterinary Epidemiological Bulletin, issued in 2013, reported a significant number of rabies cases among cattle, buffalo, swine, and goats as well.

Figure 4A shows the total number of human rabies cases reported in each district in Sri Lanka from January 2008 to September 2022. During this period, the highest number of human rabies cases (62 cases) was recorded in the Kurunegala district, while the lowest number of cases (3 cases) was reported in Kegalle and Mannar districts.

FIG. 4.

(A) Yearly fluctuations of human rabies cases reported in Sri Lanka (2000–2022). (B) Total number of human rabies cases reported by district in Sri Lanka (2008–2022). (C) Yearly fluctuations of Japanese encephalitis cases reported in Sri Lanka (2013–2022), Epidemiology Unit, Ministry of Health, Sri Lanka.

Influenza a

Swine in Sri Lanka have been found to harbor influenza A viruses genetically similar to human influenza A (H3N2) and A (H1N1) pdm09 viruses. Furthermore, the country has witnessed two instances of A (H1N1) pdm09 virus transmission from humans to pigs (Perera et al., 2013).

A total of three studies, comprising two hospital-based investigations (Perera et al., 2010; Lamabadusuriya, 2001) and one animal-based study (Perera et al., 2013), have reported the occurrence of zoonotic influenza A virus infection in Sri Lanka (Table 1). Perera et al. (2010) conducted a study involving patients admitted to the Outpatient Department at Colombo North Teaching Hospital for the treatment of acute upper respiratory tract infections from 2003 to 2004. Their findings revealed that 8% of the patients were infected with influenza A virus. Particularly, the majority (13 out of 24) of the infected patients were younger than 15 years. In addition, it was observed that the influenza viruses detected in Sri Lanka closely resembled the viruses identified in both the Northern and Southern hemispheres (Perera et al., 2010). In another study, Lamabadusuriya (2001) investigated 30 febrile patients 6 months to 10 years of age, who were admitted to the Lady Ridgeway Hospital in Colombo. Among the screened patients, zoonotic influenza A (H3N2) was detected (Lamabadusuriya, 2001).

Japanese encephalitis

Japanese encephalitis, a vector-borne zoonotic disease, can be effectively controlled using a live attenuated vaccine (Erlanger et al., 2009). According to the Epidemiology Unit of the Ministry of Health in Sri Lanka, 266 Japanese encephalitis cases were reported from 2013 to 2021. The highest number of cases, totaling 79, was reported in 2014. However, the number of reported Japanese encephalitis cases significantly decreased to 15 in 2015 and further dropped to 4 in 2021.

In a study by Jeewandara et al. (2015), 1689 dengue patients admitted to the Family Practice Center at the University of Sri Jayewardenepura, Sri Lanka, were screened for Japanese encephalitis. The findings revealed that both children and adults admitted for dengue infection were likely to test seropositive for Japanese encephalitis virus antibodies (Jeewandara et al., 2015).

West Nile virus infection

West Nile virus infection is a mosquito-borne zoonotic disease. Although it has been reported in India (Khan et al., 2011), there was no prior report of its transmission in Sri Lanka until 2015. Lohitharajah et al. (2015) conducted an enzyme-linked immunosorbent assay and a plaque reduction neutralization test to detect West Nile virus IgM in 108 clinically diagnosed encephalitis patients admitted to the National Hospital and the Lady Ridgeway Hospital in Colombo, Sri Lanka. Their study revealed that 2.8% of the study population tested positive for West Nile virus neuroinvasive disease, and these patients were between 17 and 49 years of age (Lohitharajah et al., 2015).

According to the World Health Organization (WHO), no vaccine against the West Nile virus has been approved for use in humans at present. However, integrated and comprehensive mosquito control programs, along with studies identifying local mosquito species involved in West Nile virus transmission, play a crucial role in preventing the transmission of this infection.

Monkeypox

The first case of monkeypox was diagnosed in an individual who had recently returned from Dubai, United Arab Emirates (UAE), in November 2022. This person exhibited symptoms such as enlarged lymph nodes, exhaustion, fever, and the development of skin blisters. Shortly thereafter, a second case was reported in a man who had also returned from the same country, as indicated by the Ministry of Health in Sri Lanka. It is worth noting that locally acquired monkeypox cases have not been reported in the country to date.

Chikungunya

The chikungunya virus, a member of the alphavirus family, is primarily transmitted by mosquitoes of the Aedes genus (Hapuarachchi et al., 2010; Schuffenecker et al., 2006). In Sri Lanka, the first documented case of chikungunya virus infection dates back to 1965 (Munasinghe et al., 1966). However, the virus experienced a re-emergence in 2006, resulting in a significant outbreak. Between 2006 and 2007, approximately 40,000 individuals in Sri Lanka were affected by this infectious disease (Hapuarachchi et al., 2010). It is noteworthy that 2006 also marked the first reported instance of coinfection with chikungunya and dengue in Sri Lanka (Hapuarachchi et al., 2008). In 2008, there was a resurgence in the number of reported cases, with figures similar to those seen in 2006–2007 (Hapuarachchi et al., 2010).

A study conducted in 2007 in southern Sri Lanka provided insights into the prevalence of the chikungunya virus. The research revealed that the chikungunya virus was detected in 28 out of 797 patients who presented with febrile illness, highlighting its significant role as a cause of nonspecific acute febrile illness in the southern region of the country (Reller et al., 2013).

In 2010, Hapuarachchi et al reported the presence of a mutated strain of the chikungunya virus circulating in Asia, including Sri Lanka. This mutation was found to enhance the virus's transmissibility by Aedes albopictus mosquitoes. Given the outdoor nature of these mosquitoes and their widespread distribution globally, this infection poses a substantial global threat. Therefore, it is imperative to implement effective vector control strategies to mitigate the risk of unforeseen outbreaks.

Parasitic zoonoses

Protozoa

Toxoplasmosis

Toxoplasmosis, a parasitic zoonosis with a broad geographical distribution, is caused by the protozoan parasite Toxoplasma gondii, affecting a wide range of hosts (Khan et al., 2017). During pregnancy, Toxoplasmosis poses a risk of transplacental transmission and can lead to severe fetal anomalies (Montoya and Rosso, 2005). Several cases of toxoplasmosis have been reported among pregnant women in Sri Lanka, particularly in those attending hospitals such as Colombo North Teaching Hospital (Chandrasena et al, 2016), Teaching Hospital Peradeniya (Iddawela et al., 2017), and Colombo De Soyza Maternity Hospital (Subasinghe et al., 2011).

Studies in Sri Lanka have shown that out of 393 pregnant women who visited two hospitals in Colombo between 2009 and 2014, 64 tested seropositive for anti-T. gondii IgG antibodies. However, none of the participants was positive for anti-T. gondii IgM antibodies (Chandrasena et al., 2016; Subasinghe et al., 2011). In another study involving pregnant women at the Teaching Hospital Peradeniya between 2010 and 2013, 60 were found to be positive for T. gondii IgG antibodies, with only 2 testing positive for T. gondii IgM antibodies (Iddawela et al., 2017).

An association was reported between Toxoplasma seroprevalence among pregnant women and the consumption of commercially prepared meals in Sri Lanka (Chandrasena et al., 2016). In addition, a study revealed significant associations between T. gondii infection and activities such as home gardening (p = 0.01) and the preparation and sale of meat (p = 0.05) (Iddawela et al., 2017). However, no significant association was found between T. gondii seropositivity and other risk factors, including contact with cats, blood transfusion, organ transplantation, or consumption of undercooked meat (Subasinghe et al., 2011).

According to the CDC, domestic cats and other felids are the only known definitive hosts for T. gondii. In Sri Lanka, an infection rate of 30.2% was reported for toxoplasmosis in cats in Colombo, in 2008 (Kulasena et al., 2011). Furthermore, in 2006, a study testing 86 stray dogs in Sri Lanka revealed a seroprevalence of 67.4% for T. gondii using MAT (Dubey et al, 2007).

Giardiasis

Giardiasis, a water-borne disease commonly found in impoverished rural communities, is often associated with poor hygiene practices and limited health education. A survey involving 489 children (1–12 years of age) in a tea plantation community in Sri Lanka's Kandy district reported an infection rate of 0.2% for Giardia intestinalis (Galgamuwa et al., 2016). In addition, G. intestinalis assemblages A and E were identified in fecal samples from cattle in Sri Lanka (Abeywardena et al., 2014).

Plasmodium knowlesi

Plasmodium knowlesi is a zoonotic protozoan parasite causing malaria in humans and is widely distributed in Southeast Asia. Its natural hosts are pig-tailed and long-tailed macaques (Singh and Daneshvar, 2013). Sri Lanka reported only one imported case of P. knowlesi infection (Dharmawardena et al., 2017).

Cryptosporidiosis

Cryptosporidium, a cause of childhood watery diarrhea in Sri Lanka, is commonly caused by Cryptosporidium parvum and can be zoonotically transmitted (Zahedi et al., 2016). Cryptosporidium sp. was identified among children younger than three years with watery diarrhea, admitted to four hospitals in the Central Province of Sri Lanka from 2011 to 2013. Positive cases had a history of animal contact, although the species was not identified (Sirisena et al, 2014). In addition, a case of C. parvum infection was reported in a child who underwent kidney transplantation (Weerasooriya et al., 2020). Cryptosporidium was also detected in toque macaques, gray langurs, and purple-faced langurs, marking the first report of Cryptosporidium infection in wild primates inhabiting natural forests in Sri Lanka (Ekanayake et al., 2006). Furthermore, C. bovis, C. ryanae, and six new genotypes were detected in cattle using PCR-based mutation scanning-targeted sequencing of the small subunit of nuclear ribosomal RNA, although C. parvum was not identified in preweaned calves (Abeywardena et al., 2014).

Nematodes

Brugian filariasis

Lymphatic filariasis, caused by Wuchereria bancrofti, and Brugia malayi, was previously endemic in several Sri Lankan districts, but the country has successfully controlled it through mass drug administrations. However, the emerging of brugian filariasis has been reported among children 7 to 12 years of age in the Colombo and Gampaha districts of Sri Lanka. In addition, nine individuals from the Gampaha district tested positive for anti-Brugia antibodies, suggesting subperiodic transmission of Brugia spp. (Chandrasena et al., 2016). Dogs and cats were found to be potential reservoirs for human brugian filariasis, with Brugia malayi infection reported in 36 (14.4%) dogs and 18 (13.4%) cats out of 250 dogs and 134 cats screened in the Gampaha district, Sri Lanka (Mallawarachchi et al., 2018b).

Dirofilariasis

Dirofilariasis is caused by parasitic nematodes of the genus Dirofilaria, with Dirofilaria repens, D. immitis, and D. tenuis being the most commonly detected species in humans. Sri Lanka has reported over 173 cases of human dirofilariasis, primarily caused by D. repens, in various districts since 1962. Clinical presentations often include ocular, oral, and cutaneous dirofilariasis (Iddawela et al., 2015; Jayasinghe et al., 2015). Ocular dirofilariasis is particularly prevalent in the Central Province of Sri Lanka, with a significant proportion of cases (70%) occurring in females 40 to 49 years of age (Iddawela et al., 2015). Canine dirofilariasis due to D. repens is a well-established parasitic disease in dogs and cats in Sri Lanka, with high prevalence (∼60%) reported in districts such as Gampaha, Puttalam, and Colombo (Dasanayake et al., 2022; Mallawarachchi et al., 2018a).

Toxocariasis

Toxocariasis is caused by the accidental ingestion of embryonated eggs of ascarid nematodes, Toxocara canis, and Toxocara cati, with dogs and cats as the main definitive hosts. In Sri Lanka, communities with limited access to public health and veterinary services are highly susceptible to the infection. For example, Hindagala in the Central Province of Sri Lanka reported a 43% seroprevalence for toxocariasis in children (Iddawela et al., 2003). In addition, T. canis was found in dogs, and its eggs were detected in the soil of a low-income tea estate community in the Central Province (Bandaranayaka et al., 2019). A 2017 seroprevalence study found that 62% of participants were seropositive for toxocariasis, with the highest seropositivity occurring in the 10- to 14-year-age group. Clinical presentations in seropositive cases often included unilateral reduced vision and red eye (Iddawela et al., 2017).

Angiostrongyliasis

Angiostrongyliasis is caused by Angiostrongylus cantonensis and is transmitted to humans through the ingestion of raw or undercooked slugs or snails. Although the consumption of slugs or snails is rare in Sri Lanka, a case report described a 25-year-old female in the Colombo district with Angiostrongylus infection in the vitreous eye (Ihalamulla et al., 2007). The mode of infection in Sri Lanka is likely through the consumption of fresh salads or vegetables contaminated with infected snails or slugs (Wang et al., 2008; Ihalamulla et al., 2007).

Hookworms

Zoonotic hookworm infections in humans are mainly caused by parasitic nematodes Ancylostoma ceylanicum, Ancylostoma braziliense, and Ancylostoma caninum from dogs and cats (Mallawarachchi and Samarasinghe, 2020; Bowman et al., 2010). A recent report described a 70-year-old female patient infected with A. ceylanicum in Sri Lanka (Mallawarachchi and Samarasinghe, 2020).

Cestodes

Bertielliasis

Bertielliasis, caused by Bertiella studeri, has been reported in various regions across South East Asia, South Asia, the Middle East, and Sub-Saharan Africa. This parasitic cestode primarily infects Old World monkeys. In Sri Lanka, human infections with B. studeri have been reported from the Southern Province (Karunaweera et al., 2001), the Sabaragamuwa Province (Morawakkorala et al., 2006), and the Central Province (Amarasinghe et al., 2020). Most reported patients in Sri Lanka were children younger than 11 years, and transmission typically occurs through accidental ingestion of the cysticercoid stage in infected intermediate host mites (Amarasinghe et al., 2020). Settlements bordering jungles in Sri Lanka are at a higher risk of infection due to frequent visits by Ceylon torque monkeys and gray langurs. Habitat loss due to deforestation and urbanization has led to increased monkey–human interactions, as the monkeys scavenge for food (Morawakkorala et al., 2006).

Sparganosis

Sparganosis is caused by the cestode Spirometra, which resides in snakes and frogs. Humans become infected through the consumption of raw or undercooked meat from frogs and snakes, drinking contaminated water, or applying poultices. Although Sri Lankans do not typically consume frog or snake meat, one case report described two patients from the Kurunegala and Kalutara districts infected with Spirometra sp. in the anterior abdominal wall (Dissanaike et al., 2001). In addition, the first case of cerebral sparganosis in Sri Lanka was reported in a 13-year-old boy in 2007 (Alibhoy et al., 2009). The most likely mode of infection in Sri Lanka is accidental ingestion of contaminated water containing Spirometra larvae, as poultices made from infected hosts are not commonly used (Alibhoy et al., 2009).

Zoonoses caused by other cestodes

Hydatidosis, a zoonotic disease caused by Echinococcus granulosus, is rare in native Sri Lankans, with most reported cases occurring in foreigners or individuals who have traveled to Central Asian countries (Matossian et al., 1997). Hymenolepis diminuta and Taenia taeniaeformis have been reported in human patients by clinicians and parasitologists in Sri Lanka, with case reports of hymenolepiasis caused by H. diminuta in a five-year-old boy (Sinhabahu et al., 2014) and T. taeniaeformis infection in a 7-year-old girl from a densely populated slum area in Colombo (Ekanayake et al., 1999). In addition, two case reports have described pet-associated Dipylidium caninum infections in children in Sri Lanka (Wijesundera and Ranaweera, 1989).

Discussion

Sri Lanka has a free health care system dedicated to maintaining continuous and quality health care services, ensuring clinical effectiveness and patient safety. The country's central health budget allocations have seen a consistent increase from 2015 to 2021. In 2021, LKR 212.3 billion was allocated for the health sector, with LKR 1.5 billion earmarked for the control of communicable and noncommunicable diseases (UNICEF, 2021). The Epidemiological Unit, established with assistance from the WHO, plays a pivotal role in bolstering surveillance, prevention, and control of communicable diseases, while ensuring the efficient dissemination of epidemiological information across the nation.

Despite these efforts, communicable diseases remain a significant health challenge in Sri Lanka. A substantial portion of the communicable disease burden is attributed to zoonoses. This study was undertaken to identify zoonotic diseases reported in Sri Lanka from 2000 to 2022.

Our findings, in conjunction with data from the Epidemiological Unit, Ministry of Health, Sri Lanka, revealed that leptospirosis is the most prevalent zoonotic disease, responsible for the highest number of reported cases in the country during the period from 2007 to 2022. Despite vigilant surveillance and systematic outpatient and inpatient management, over 150 leptospirosis cases were reported in each district of Sri Lanka during the study period. Notably, we observed an association between leptospirosis incidence and paddy cultivation during the “Yala” and “Maha” seasons, (May to August) (Fig. 3), where case numbers surged significantly, despite numerous control measures and guidance provided to paddy farmers (Yathramullage and Meegaskumbura, 2016).

The Ratnapura district, renowned for its gem mining industry, documented the highest number of leptospirosis cases, totaling 9,905 between 2007 and 2022. The Kalutara district ranked second in the number of reported cases, potentially linked to the increased occurrence of storms and floods in the region (Grama Niladhari Divisions Statistics-Kalutara District, 2020). The proliferation of rodents in urban areas due to rapid urbanization further compounds this issue (Agampodi et al., 2011). In Sri Lanka, small mammals such as Rattus, Bandicota indica, B. bengalensis, Mus musculus, Mus cervicolor, and Suncus murinus (Yathramullage and Meegaskumbura, 2016) are recognized as significant reservoirs for human leptospirosis. The elevated incidence of leptospirosis cases in Colombo, Galle, and Gampaha districts may be attributed to higher rodent populations in urban settings (Fig. 2C). In addition, cattle serve as important reservoirs for human leptospirosis (Gamage et al., 2014).

For early leptospirosis diagnosis, various methods, including indirect hemagglutination assays, ELISA, hemolytic tests, immobilized antigen dipsticks, and lateral flow assays, are employed. However, the microscopic agglutination test (MAT) is considered the gold standard serological test for diagnosing leptospirosis (WHO, 2009). In Sri Lanka, PCR is the most widely used diagnostic method for human leptospirosis. Furthermore, it has been determined that IgM ELISA is more sensitive than MAT for early and acute phase diagnosis, while immunochromatography tests can be utilized for rapid diagnosis (Niloofa et al., 2015).

The major risk factors for rickettsioses in Sri Lanka include high exposure to scrub jungles (Kularatne et al., 2013; De Silva et al., 2012) and contact with domesticated animals (Liyanaarachchi et al., 2015; Nanayakkara et al., 2013). In the Central Hills of Sri Lanka, ticks on dogs and wild boars were identified as possible vectors of spotted fever group infections (Kularatne et al., 2013). The geographical distribution of typhus fever showed an association with risk factors. Figure 2D illustrates the geographical distribution of typhus fever, with the Jaffna district reporting the highest number of cases. In Jaffna, most children infected with scrub typhus had been exposed to household pets (mainly dogs), slept on the floor, or lived in proximity to jungles (Sathiadas et al., 2013). Apart from the Northern region, a relatively high number of typhus cases were reported in districts like Kandy, Nuwara Eliya, Monaragala, Hambantota, Badulla, and Matara, while the Ampara district reported the lowest number of typhus fever cases during the study period (Fig. 2D).

Torgerson et al. (2015) estimated the worldwide burden of leptospirosis to be 2.90 million Disability-Adjusted Life Years (DALYs) annually, with Sri Lanka experiencing a burden exceeding 500 DALYs per 100,000 individuals per year. However, it is worth noting that our study did not involve the calculation of DALYs. Instead, our systematic review focused solely on the prevalence of leptospirosis in Sri Lanka. Similarly, Costa et al. (2015) reported a prevalence of over 100 cases of leptospirosis per 100,000 population in Sri Lanka. Although we did not calculate the DALYs, our results indicate that the annual prevalence of leptospirosis was significantly higher during our study period. Moreover, Torgerson et al. (2015) reported that morbidity rates were notably elevated in studies conducted among rural populations and tropical areas when compared to urban settings within the region.

For diagnosing typhus and spotted fever group rickettsioses, the “gold standard” technique is the immunofluorescence assay (IFA). However, other serological tests such as ELISA and Weil-Felix are also widely used for diagnostic purposes. In addition, molecular methods such as PCRs and DNA sequencing enable the rapid identification of rickettsiae at the species level (Stewart and Stewart, 2021). In Sri Lanka, the diagnosis of rickettsioses employs immunofluorescence antibody tests (Kularatne et al., 2013; Nanayakkara et al., 2013), IgG and IgM ELISA (Pradeepan et al., 2014), PCR (Liyanaarachchi et al., 2015), and basic biochemical tests (Premaratna et al., 2008).

Factors hindering the control of certain bacterial zoonoses in the country include poverty and lack of awareness among high-risk groups. Infections such as rickettsioses (Sathiadas et al., 2013) and brucellosis (Karunanayake et al., 2019; Kothalawala et al., 2018) were primarily reported among low-income and/or rural communities with limited access to infrastructure and health education. We also noted that the true burden of some bacterial zoonoses may not have been accurately assessed due to symptomatic diagnosis. Patients with fever, for example, are frequently reported in the country, and etiologies are not always confirmed. We observed that Q fever was reported as the etiological factor among patients with an unknown origin of fever (Angelakis et al., 2012). Furthermore, foodborne bacterial zoonotic diseases may have been underreported in the country due to treatment procedures that rely solely on symptoms. Although we found one study reporting zoonotic Shigella sp. in children in Jaffna (Sathiadas et al., 2016), we found no scientific report on campylobacteriosis or salmonellosis, despite these pathogens being identified as the main causes of food poisoning worldwide by the WHO. However, the detection of foodborne bacterial pathogens in wild animals, such as toque macaques (Tegner et al., 2019), and in food (Jayaweera et al., 2020; Wijendra et al., 2014; Gunasena et al., 1995) suggests the potential for future outbreaks in the country. Therefore, we recommend revising and implementing national standards to enhance the quality of food consumed by the population and conducting systematic investigations into food poisoning complaints to minimize or prevent unforeseen threats from bacterial foodborne infections.

In the early 2000s, the Sri Lankan government allocated nearly $3.0 million per year for rabies and Japanese encephalitis immunization programs (Nanayakkara et al., 2003; Attanyake and Stevenson, 2001). As a result, Sri Lanka witnessed a notable decline in the incidence of Japanese encephalitis (Epidemiology unit MoH, Sri Lanka, 2012) and rabies over the last decade (Silva, 2016).

In 1988, the Epidemiology Unit of the Ministry of Health initiated an immunization program against Japanese encephalitis, targeting children one to ten years of age. Interestingly, in the postvaccination era, Japanese encephalitis cases were predominantly reported in individuals older than 30 years, who had not been immunized against the disease (Epidemiology Unit, MoH, 2012). The Department of Animal Production and Health in Sri Lanka previously conducted a program to immunize pigs, which serve as important amplifying hosts for Japanese encephalitis (McLean and Graham, 2022). However, the Epidemiology Unit of the Ministry of Health in Sri Lanka suggested that this program could be discontinued due to its ineffectiveness (Epidemiology Unit, MoH, 2012). Nevertheless, Peiris et al. (1992) reported that the reduction in vector infection with the Japanese encephalitis virus was roughly proportional to the extent of the pig vaccination program (Peiris et al., 1992).

The reduction in the number of human rabies cases in Sri Lanka since 2006 can be attributed to antirabies vaccination programs for dogs and community awareness initiatives conducted by government agencies (Silva, 2016). For instance, according to Public Health Veterinary Services, Sri Lanka administered 1.5 million and 1.3 million antirabies vaccines in the years 2014 and 2017, underscoring the importance of these vaccination programs in the country's efforts to eliminate rabies. However, there is a need to investigate the presence of rabies virus in animals other than canines, such as cattle, buffalo, swine, goats, and wildlife, to identify potential reservoirs of rabies in the country. Although the incidence of Japanese encephalitis is decreasing in the known hot spots of the country, it appears to be spreading to new areas that previously had a low level of transmission (Epidemiology unit MoH, Sri Lanka, 2012). Therefore, we emphasize the importance of surveillance programs following mass immunizations to assess the success of immunization programs.

Nonhuman primates, along with other vertebrates, are believed to serve as amplification hosts for chikungunya virus. In Zimbabwe, African green monkeys and chacma baboons (Papio ursinus) have been identified as significant hosts (McIntosh et al., 1964). In addition, the chikungunya virus has been isolated from African green monkeys, Patas monkeys (Erythrocebus patas), and Guinea baboons (Papio papio) in Senegal (Diallo et al., 1999). Seropositivity to the virus has also been observed in chimpanzees in the Congo (Osterrieth et al., 1920). However, conclusive evidence of enzootic circulation of the chikungunya virus in Sri Lanka is lacking. Therefore, comprehensive studies are warranted to investigate the potential enzootic transmission of the chikungunya virus in Sri Lanka.

Enzootic transmission of the West Nile virus primarily involves mosquitoes, migratory birds, horses, and crocodiles (Habarugira et al., 2020). However, to date, no study has been conducted on the enzootic transmission of the West Nile virus in Sri Lanka. Therefore, we emphasize the importance of investigating the epidemiology and animal reservoirs of the West Nile virus in Sri Lanka.

The global incidence and burden of congenital toxoplasmosis (190,100 annual cases, with a 95% CI of 179,300–206,300) were estimated by region. This equates to an incidence rate of approximately 1.5 cases of CT per 1000 live births. However, it is notable that the South Asia region, including Sri Lanka, was excluded or not considered in this study. The areas included in the analysis were AFR (African Region), AMR (Region of the Americas), CI (credible interval), DALYs (Disability-Adjusted Life Years), EMR (Eastern Mediterranean Region), EUR (European Region), SEAR (South-East Asia Region), and WPR (Western Pacific Region) (Torgerson and Pierpaolo., 2013). However, in our analysis, we presented the reported prevalence of toxoplasmosis in Sri Lanka without calculating the DALYs. Although studies in Sri Lanka have been limited to specific areas, comprehensive island-wide surveys of congenital toxoplasmosis have not been conducted to determine its true prevalence and incidence rates. Thus, these findings highlight the importance of conducting seroprevalence studies and understanding and addressing the risk factors associated with toxoplasmosis transmission, especially among pregnant women, to mitigate the potential adverse effects on fetal health.

Parasitic zoonoses accounted for a smaller number of cases compared to bacterial and viral zoonoses. However, we identified 14 parasitic zoonoses that infected people in Sri Lanka. Toxoplasmosis was reported among pregnant women in Sri Lanka (Iddawela et al., 2017; Chandrasena et al., 2016; Subasinghe et al., 2011), but its pooled prevalence in Sri Lanka was lower compared to some other South Asian and Southeast Asian countries such as India, Bangladesh, Nepal, and Myanmar (Rostami et al., 2020). In addition, parasitic zoonoses like giardiasis (Galgamuwa et al., 2016), cryptosporidiosis (Sirisena et al., 2014), toxocariasis (Iddawela et al., 2003), and bertielliasis (Amarasinghe et al., 2020; Morawakkorala et al., 2006; Karunaweera et al., 2001) were predominantly reported among children, likely due to poor hygiene practices and/or accidental ingestion of contaminated food or soil. Sri Lanka has successfully controlled lymphatic filariasis caused by Wuchereria bancrofti, a WHO-declared neglected tropical disease, through mass drug administrations and stringent control measures (Epidemiology Unit, 2022). However, the emergence of subperiodic brugian filariasis in humans poses a new threat to the lymphatic filariasis control program. Dogs and cats are the main suspected reservoir animals for subperiodic brugian filariasis in Sri Lanka, necessitating further studies in collaboration with local, regional, and national levels.

During the study period, no report of fungal zoonoses among people in Sri Lanka was found. Furthermore, notifiable diseases of animal origin such as tuberculosis, babesiosis, Middle East respiratory syndrome, plague, Ebola, and the Nipah virus were not reported in Sri Lanka. However, zoonotic tuberculosis, the Nipah virus, and babesiosis have been reported in neighboring India, although outbreaks of Ebola and the Middle East respiratory syndrome were not reported (Chattu et al., 2018; Bapat et al., 2017).

Our analysis indicated that Colombo, the main commercial hub of Sri Lanka, reported the highest number of zoonoses compared to other parts of the country. Plausible factors contributing to this include poor hygiene practices, lack of individual water connections, inadequate wastewater disposal in slum settlements, the presence of stray dogs and cats, and an uncontrolled rodent population in the Colombo district (Madubhashini and Dayawansa, 2017). In addition, many studies in our review included patient populations from the Colombo district, leading to more reports on zoonoses in Colombo compared to other districts in Sri Lanka.

Practical strategies for detecting and responding to anticipated or unexpected zoonotic threats are necessary. The “One Health” approach offers a framework to address complex health threats, integrating human, animal, and environmental health. Sri Lanka has successfully used the “One Health” approach to reduce the burden of leptospirosis and rabies (Acharya et al., 2021; Epidemiology Unit, 2014). However, cost-effectiveness, surveillance strategies, laboratory facilities, and workforce requirements may pose challenges when implementing the One Health concept (Dahal et al., 2017). A more practical and generalized five-step One Health framework has been introduced for zoonotic disease control at the local or international level, encompassing engagement, assessment, planning, implementation, and monitoring and evaluation (Ghai et al., 2022). Sri Lanka, as a developing country, has effectively combated various neglected tropical diseases such as rabies, Japanese encephalitis, lymphatic filariasis, and malaria. Nevertheless, Sri Lanka requires a customized, country-specific “One Health” approach considering the factors vector surveillance, risk analysis, and efficient surveillance system to capture zoonotic diseases in domestic and wild animals, collaboration among human, animal, and environmental health sectors, strengthening laboratory capacities, awareness campaigns, and legal framework for rapid outbreak response and containment to effectively control and eliminate zoonoses in Sri Lanka.

Conclusions

Based on the systematic review, Sri Lanka can be categorized as a country with a moderate risk of zoonotic disease transmission. Over the study period (2000–2022), 14 parasitic, 7 bacterial, and 7 viral zoonoses have been reported in Sri Lanka. Leptospirosis emerged as the most reported zoonotic disease in the country. Notably, some zoonoses such as babesiosis, Middle East respiratory syndrome, plague, Ebola, Nipah virus, and Zika virus were not reported in Sri Lanka during this period.

Challenges such as tropical climate-induced flooding, occupational exposure, animal reservoirs/carriers, wildlife interactions, poverty, misdiagnosis, lack of awareness, and information gaps contribute to the burden of zoonoses in Sri Lanka. A customized and country-specific approach is needed to mitigate this burden, focusing on surveillance, early detection, and appropriate control measures. The “One Health” approach, which balances the health of humans, animals, and the environment, is recommended as a framework to address emerging and re-emerging zoonotic diseases in Sri Lanka.

Footnotes

Author Disclosure Statement

No conflicting financial interests exist.

Funding Information

This work was not supported by a grant.

References

Abebe

, Gugsa

, Ahmed

. Review on major food-borne zoonotic bacterial pathogens. J Trop Med, 2020; 29:2020:4674235; doi: 10.1155/2020/4674235

Abeywardena

, Koehler

, Rajapakse

RPVJ

, et al. First molecular characterization of Cryptosporidium and Giardia from bovines (Bos taurus and Bubalus bubalis) in Sri Lanka: Unexpected absence of C. parvum from pre-weaned calves. Parasit Vectors, 2014; 7:75; doi: 10.1186/1756-3305-7-75

Acharya

, Subedi

, Wilson

. Rabies control in South Asia requires a One Health approach. One Health, 2021; 12:100215; doi: 10.1016/j.onehlt.2021.100215

Agampodi

, Peacock

, Thevanesam

, et al. Leptospirosis outbreak in Sri Lanka in 2008: Lessons for assessing the global burden of disease. Am J Trop Med Hyg, 2011; 85(3):471–478; doi: 10.4269/ajtmh.2011.11-0276

Alibhoy

, Fernando

, Perera

. A case of cerebral sparganosis. Ceylon Med J, 2009; 52(3):93–94; doi: 10.4038/cmj.v52i3.968

Allen

, Murray

, Zambrana-Torrelio

, et al. Global hotspots and correlates of emerging zoonotic diseases. Nat Commun, 2017; 8(1):1124; doi: 10.1038/s41467-017-00923-8

Amarasinghe

, Le

, Wickramasinghe

. Bertiella studeri Infection in Children, Sri Lanka. Emerg Infect Dis, 2020; 26(8):1889–1892; doi: 10.3201/eid2608.200324

Angelakis

, Munasinghe

, Yaddehige

, et al. Detection of rickettsioses and Q fever in Sri Lanka. Am J Trop Med Hyg, 2012; 86(4):711–712; doi: 10.4269/ajtmh.2012.11-0424

Attanyake

, Stevenson

. Asian Vaccination Initiative, Sri Lanka National Immunization Program, Financing Assessment. 2001 971-561-348-9 Publication Stock No. 020201, Published by the Asian Development Bank P.O. Box 789, 0980 Manila, Philippines. Available at: https://www.adb.org/sites/default/files/publication/27922/natl-immunization.pdf

10.

Bandara

, Weerasekera

, Gunasekara

, et al. Molecular characterization and disease severity of leptospirosis in Sri Lanka. Mem Inst Oswaldo Cruz, 2015; 110(4):485–491; doi: 10.1590/0074-02760150070

11.

Bandaranayaka

, Rajapakse

RPVJ

, Rajakaruna

. Potentially zoonotic gastrointestinal parasites of dogs in Lunugala tea estate community in Central Sri Lanka. Ceylon J Sci, 2019; 48(1):43–50; doi: 10.4038/cjs.v48i1.7587

12.

Bapat

, Dodkey

, Shekhawat

, et al. Prevalence of zoonotic tuberculosis and associated risk factors in Central Indian populations. J Epidemiol Glob Health, 2017; 7(4):277–283; doi: 10.1016/j.jegh.2017.08.007

13.

Beck

, Gunawardena

, Horton

, et al. Pathobiological investigation of naturally infected canine rabies cases from Sri Lanka. BMC Vet Res, 2017; 13(1):99–99; doi: 10.1186/s12917-017-1024-5

14.

Bowman

, Montgomery

, Zajac

, et al. Hookworms of dogs and cats as agents of cutaneous larva migrans. Trends Parasitol, 2010; 26(4):162–167; doi: 10.1016/j.pt.2010.01.005

15.

Chandrasena

, Herath

, Rupasinghe

, et al. Toxoplasmosis awareness, seroprevalence and risk behavior among pregnant women in the Gampaha district, Sri Lanka. Pathog Glob Health, 2016; 110(2):62–67; doi: 10.1080/20477724.2016.1173325

16.

Chandrasena

, Premaratna

, Samarasekera

, et al. Surveillance for transmission of lymphatic filariasis in Colombo and Gampaha districts of Sri Lanka following mass drug administration. Trans R Soc Trop Med Hyg, 2016; 110(10):620–622; doi: 10.1093/trstmh/trw067

17.

Chattu

, Kumar

, Kumary

, et al. Nipah virus epidemic in southern India and emphasizing “One Health” approach to ensure global health security. J Family Med Prim Care, 2018; 7(2):275–283; doi: 10.4103/jfmpc.jfmpc_137_18

18.

Costa

, Hagan

, Calcagno

, et al. Global morbidity and mortality of leptospirosis: A systematic review. P LoS Negl Trop Dis, 2015; 17:9(9):e0003898; doi: 10.1371/journal.pntd.0003898

19.

Chomel

, Belotto

, Meslin

. Wildlife, exotic pets, and emerging zoonoses. Emerg Infect Dis, 2007; 13(1):6–11; doi: 10.3201/eid1301.060480

20.

Dahal

, Upadhyay

, Ewald

. One Health in South Asia and its challenges in implementation from stakeholder perspective. Vet Rec, 2017; 181(23):626–626; doi: 10.1136/vr.104189

21.

Dasanayake

, Balendran

, Atapattu

, et al. A study on canine dirofilariasis in selected areas of Sri Lanka. BMC Res Notes, 2022; 15(1):137; doi: 10.1186/s13104-022-06024-0

22.

De Silva

, Wijesundara

, Liyanapathirana

, et al. Scrub typhus among pediatric patients in Dambadeniya: A base hospital in Sri Lanka. Am J Trop Med Hyg, 2012; 87(2):342–344; doi: 10.4269/ajtmh.2012.12-0170

23.

Dharmawardena

, Rodrigo

, Mendis

, et al. Response of imported malaria patients to antimalarial medicines in Sri Lanka following malaria elimination. PLoS One, 2017; 12(11):e0188613; doi: 10.1371/journal.pone.0188613

24.

Diallo

, Thonnon

, Traore-Lamizana

, et al. Vectors of Chikungunya virus in Senegal: Current data and transmission cycles. Am J Trop Med Hyg, 1999; 60(2):281–286; doi: 10.4269/ajtmh.1999.60.281

25.

Dissanaike

, Anthonis

, Sheriffdeen

, et al. Two more cases of sparganosis from Sri Lanka. Ceylon J Med Sci, 2001; 44(1); doi: 10.4038/cjms.v44i1.4869

26.

Don Bamunusinghage

, Dangolla

, Hettiarachchi

, et al. Challenges and opportunities for wildlife disease surveillance in Sri Lanka. J Wildl Dis, 2020; 56(3):538–546; doi: 10.7589/2019-07-181

27.

Dubey

, Rajapakse

RPVJ

, Wijesundera

, et al. Prevalence of Toxoplasma gondii in dogs from Sri Lanka and genetic characterization of the parasite isolates. Vet Parasitol, 2007; 146(3-4):341–346; doi: 10.1016/j.vetpar.2007.03.009

28.

Durrance-Bagale

, Rudge

, Singh

, et al. Drivers of zoonotic disease risk in the Indian subcontinent: A scoping review. One Health, 2021; 13:100310; doi: 10.1016/j.onehlt.2021.100310

29.

Ehelepola

NDB

, Basnayake

BMLS

, Sathkumara

SMBY

, et al. Two atypical cases of hantavirus infections from Sri Lanka. Case Rep Infect Dis, vol. 2018, Article ID 4069862, 6 pages, 2018. doi; 10.1155/2018/4069862

30.

Ekanayake

, Arulkanthan

, Horadagoda

, et al. Prevalence of Cryptosporidium and other enteric parasites among wild non-human primates in Polonnaruwa, Sri Lanka. Am J Trop Med Hyg, 2006; 74(2):322–329; doi: 10.4269/ajtmh.2006.74.322

31.

Ekanayake

, Warnasuriya

, Samarakoon

, et al. An unusual ‘infection ‘of a child in Sri Lanka, with Taenia taeniaeformis of the cat. Ann Trop Med Parasitol, 1999; 93(8):869–873; doi: 10.1080/00034983.1999.11813494

32.

Epidemiology Unit. Ministry of Health, Sri Lanka. Epidemiological bulletin volume 48; 1st quarter, 2007

33.

Epidemiology Unit. Ministry of Health, Sri Lanka. Weekly epidemiology report, 2017; 44(9).

34.

Epidemiology Unit. Ministry of Health, Sri Lanka. Human Rabies. Weekly epidemiology report 2022; 49(10).

35.

Epidemiology Unit. Ministry of Health, Sri Lanka. One Health Approach for disease prevention. Weekly epidemiology report 2014; 41(13).

36.

Epidemiology Unit. National Guidelines on Management of Leptospirosis. Ministry of Health, Nutrition and Indigenous Medicine, Sri Lanka; 2016.

37.

Erlanger

, Weiss

, Keiser

, et al.. Past, present, and future of Japanese encephalitis. Emerg Infect Dis, 2009; 15(1):1–7; doi: 10.3201/eid1501.080311

38.

Fernando

., Bandara

J. S

., & Smith

. (2016). Tourism in Sri Lanka. In M. C. Hall & S. J. Page (Eds.), The Routledge Handbook of Tourism in Asia (pp. 251–264). Abingdon, Oxon, UK: Routledge.

39.

Franc

, Krecek

, Häsler

, Arenas-Gamboa

. Brucellosis remains a neglected disease in the developing world: a call for interdisciplinary action. BMC Public Health, 2018; 11:18(1):125 doi: 10.1186/s12889-017-5016-y

40.

Galgamuwa

, Iddawela

, Dharmaratne

. Intestinal protozoa infections, associated risk factors and clinical features among children in a low-income tea plantation community in Sri Lanka. Int J Community Med Public Health, 2016; 3(9):2452–2458; doi: 10.1820/3/2394-6040.ijcmph20163053

41.

Gamage

, Koizumi

, Perera

, et al. Carrier status of leptospirosis among cattle in Sri Lanka: A zoonotic threat to public health. Transbound Emerg Dis, 2014; 61(1):91–96; doi: 10.1111/tbed.12014

42.

Gamage

, Yasuda

, Nishio

, et al. Serological evidence of Thailand virus-related hantavirus infection among suspected leptospirosis patients in Kandy, Sri Lanka. Jpn J Infect Dis, 2011; 64(1):72–75; doi: 10.7883/yoken.64.72

43.

Ghai

, Wallace

, Kile

, et al. A generalizable one health framework for the control of zoonotic diseases. Sci Rep, 2022; 12(1):8588; doi: 10.1038/s41598-022-12619-1

44.

Grace

, Gilbert

, Randolph

, et al. The multiple burdens of zoonotic disease and an ecohealth approach to their assessment. Trop Anim Health Prod, 2012; 44 Suppl 1:S67–73; doi: 10.1007/s11250-012-0209-y

45.

Grace

, Lindahl

, Wanyoike

, et al. Poor livestock keepers: Ecosystem–poverty–health interactions. Philos Trans R Soc Lond B Biol Sci, 2017; 372(1725):20160166; doi: 10.1098/rstb.2016.0166

46.

Grama Niladhari Divisions Statistics-Kalutara District. Department of Census and Statistics, Ministry of Economic Policies and Plan Implementation, 2020 of Census & Statistics “Sankyana Mandiraya” No. 306/71, Polduwa Road, Battaramulla, Sri Lanka. ISBN 978-624-5919-08-6 http://www.statistics.gov.lk/Resource/en/Population/GND_Reports/2020/Kalutara.pdf

47.

Gunasena

, Kodikara

, Ganepola

, et al. Occurrance of Listeria monocytogenes in food in Sri Lanka J. Natn. Sci. Coun. Sri Lanka, 1995;23(3):107–114; doi: 10.4038/jnsfsr.v23i3.5848

48.

Habarugira

, Suen

, Hobson-Peters

, et al. West Nile Virus: An Update on Pathobiology, Epidemiology, Diagnostics, Control and “One Health” Implications. Pathogens, 2020; 9(7):589; doi: 10.3390/pathogens9070589

49.

Hapuarachchi

HAC

, Bandara

KBAT

, Hapugoda

, et al. Laboratory confirmation of dengue and Chikungunya co-infection. Ceylon Med J, 2008; 53(3):104–105; doi: 10.4038/cmj.v53i3.252

50.

Hapuarachchi

, Bandara

KBAT

, Sumanadasa

SDM

, et al. Re-emergence of Chikungunya virus in South-east Asia: Virological evidence from Sri Lanka and Singapore. J Gen Virol, 2010; 91(Pt 4):1067–1076; doi: 10.1099/vir.0.015743-0

51.

Iddawela

, Ehambaram

, Atapattu

, et al. Frequency of toxocariasis among patients clinically suspected to have visceral toxocariasis: A retrospective descriptive study in Sri Lanka. J Parasitol Res, 2017; 2017:4368659; doi: 10.1155/2017/4368659

52.

Iddawela

, Ehambaram

, Wickramasinghe

. Human ocular dirofilariasis due to Dirofilaria repens in Sri Lanka. Asian Pac J Trop Med, 2015; 8(12):1022–1026; doi: 10.1016/j.apjtm.2015.11.010

53.

Iddawela

, Vithana

SMP

, Ratnayake

. Seroprevalence of toxoplasmosis and risk factors of Toxoplasma gondii infection among pregnant women in Sri Lanka: A cross sectional study. BMC Public Health, 2017; 17(1):930–936; doi: 10.1186/s12889-017-4941-0

54.

Iddawela

, Kumarasiri

, Wijesundera

MDS

. A seroepidemiological study of toxocariasis and risk factors for infection in children in Sri Lanka. Southeast Asian J Trop Med Public Health, 2003; 34(1):7–15.

55.

Ihalamulla

, Fernando

, Weerasena

, et al. A further case of Parastrongyliasis (= Angiostrongyliasis) from the eye of a patient in Sri Lanka. Ceylon J Med Sci, 2007; 50(1); doi: 10.4038/cjms.v50i1.118

56.

Jayasinghe

, Gunawardane

, Sitheeque

MAM

, et al. A case report on oral subcutaneous dirofilariasis. Case Rep Infect Dis, 2015; 2015:648278; doi: 10.1155/2015/648278

57.

Jayasundara

, Senavirathna

, Warnasekara

, et al. 12 Novel clonal groups of Leptospira infecting humans in multiple contrasting epidemiological contexts in Sri Lanka. PLoS Negl Trop Dis, 2021; 15(3):e0009272; doi: 10.1371/journal.pntd.0009272

58.

Jeewandara

, Gomes

, Paranavitane

, et al. Change in dengue and Japanese encephalitis seroprevalence rates in Sri Lanka. PLoS One, 2015; 10(12):e0144799; doi: 10.1371/journal.pone.0144799

59.

Jayaweera

TSP

, Ruwandeepika

HAD

, Deekshit

, et al. Isolation and identification of Salmonella spp. from broiler chicken meat in Sri Lanka and their antibiotic resistance. J Agric Sci (Sri Lanka). 2020; 15(3):395; doi: 10.4038/jas.v15i3.9031

60.

Jones

, Patel

, Levy

, et al. Global trends in emerging infectious diseases. Nature, 2008; 451(7181):990–993; doi: 10.1038/nature06536

61.

Kalupahana

, Mughini-Gras

, Kottawatta

, et al.. Weather correlates of Campylobacter prevalence in broilers at slaughter under tropical conditions in Sri Lanka. Epidemiol Infect. 2018; 146:(8):972–979; doi: 10.1017/S0950268818000894

62.

Karunanayake

, Karunanayake

, Rathnayaka

, et al. Seroprevalence and associated risk factors of human Brucella infection in selected provinces in Sri Lanka. Ceylon Med J, 2019; 64(1):25–29; doi: 10.4038/cmj.v64i1.8824

63.

Karunaweera

, Ihalamulla

, Wickramathanthri

, et al. Bertiella studeri: A case of human infection. Ceylon J Med Sci, 2001; 44(1); doi: 10.4038/cjms.v44i1.4870

64.

Khan

, Dutta

, Khan

, et al. West Nile virus infection, Assam, India. Emerg Infect Dis, 2011; 17(5):947–948; doi: 10.3201/eid1705.100479

65.

Khan

, Rashid

, Akbar

, et al. Seroprevalence of Toxoplasma gondii in South Asian countries. Rev Sci Tech, 2017; 36(3):981–996; doi: 10.2050/6/rst.36.3.2730

66.

Kothalawala

, Makita

, Kothalawala

, et al. Knowledge, attitudes, and practices (KAP) related to brucellosis and factors affecting knowledge sharing on animal diseases: A cross-sectional survey in the dry zone of Sri Lanka. Trop Anim Health Prod, 2018; 50(5):983–989; doi: 10.1007/s11250-018-1521-y

67.

Kularatne

SAM

, Rajapakse

RPVJ

, Wickramasinghe

WMRS

, et al. Rickettsioses in the central hills of Sri Lanka: Serological evidence of increasing burden of spotted fever group. Int J Infect Dis, 2013; 17(11):e988–e992; doi: 10.1016/j.ijid.2013.05.014

68.

Kulasena

, Rajapakse

RPVJ

, Dubey

, et al. Seroprevalence of Toxoplasma gondii in cats from Colombo, Sri Lanka. J Parasitol, 2011; 97(1):152–152; doi: 10.1645/GE-2640.1

69.

Lamabadusuriya

. Multi-organ failure due to influenza A viral infection-A Sri Lankan experience. Sri Lanka J Child Health, 2009; 30(4):87–93; doi: 10.4038/sljch.v30i4.827

70.

Laxminarayan

, Kakkar

, Horby

, et al. Emerging and re-emerging infectious disease threats in South Asia: Status, vulnerability, preparedness, and outlook. Bmj, 2017; 357:j1447; doi: 10.1136/bmj.j1447

71.

Livestock statistical bulletin. Department of Animal Production and Health, Peradeniya, Sri Lanka; 2020.

72.

Liyanaarachchi

, Rajakaruna

, Rajapakse

RPVJ

. Spotted fever group rickettsia in ticks infesting humans, wild and domesticated animals of Sri Lanka: One health approach. Ceylon J Sci (Biol Sci), 2016; 44(2):67–74; doi: 10.4038/cjsbs.v44i2.7351

73.

Lohitharajah

, Malavige

, Chua

AJS

, et al. Emergence of human West Nile virus infection in Sri Lanka. BMC Infect Dis, 2015; 15(1):305–306; doi: 10.1186/s12879-015-1040-7

74.

Lokupathirage

, Muthusinghe

, Shimizu

, et al. Serological evidence of Thailand orthohantavirus or antigenically related virus infection among rodents in a chronic kidney disease of unknown etiology endemic area, Girandurukotte, Sri Lanka. Vector Borne Zoonotic Dis, 2019; 19(11):859–866; doi: 10.1089/vbz.2018.2429

75.

Madubhashini

PVS

, Dayawansa

NDK

. Water use and hygiene practices of a slum community in Colombo district: A gender focused study. 6th YSF proceedings; 2017.

76.

Magouras

, Brookes

, Jori

, et al. Emerging zoonotic diseases: Should we rethink the animal–human interface? Front Vet Sci, 2020; 7:582743; doi: 10.3389/fvets.2020.582743

77.

Mallawarachchi

, Chandrasena

, Wickramasinghe

, et al. A preliminary survey of filarial parasites in dogs and cats in Sri Lanka. PLoS One, 2018a;13(11):e0206633; doi: 10.1371/journal.pone.0206633

78.

Mallawarachchi

, Nilmini Chandrasena

TGA

, Premaratna

, et al. Human infection with sub-periodic Brugia spp. in Gampaha District, Sri Lanka: A threat to filariasis elimination status? Parasit Vectors, 2018b;11(1):68–66; doi: 10.1186/s13071-018-2649-3

79.

Mallawarachchi

, Samarasinghe

. Ancylostoma ceylanicum first ever case detected in Sri Lanka. Austin J Clin Case Rep, 2020; 7(1):1162.

80.

Matossian

, Rickard

, Smyth

. Hydatidosis: A global problem of increasing importance. Bull World Health Organ, 1997; 55(4):499–507.

81.

Matossian

. The immunological diagnosis of human hydatid disease. Trans R Soc Trop Med Hyg, 1977; 71(2):101–104; doi: 10.1016/0035-9203(77)90070-0

82.

Matsumoto

, Ahmed

, Karunanayake

, et al. Molecular epidemiology of human rabies viruses in Sri Lanka. Infect Genet Evol, 2013; 18:160–167; doi: 10.1016/j.meegid.2013.05.018

83.

McIntosh

, Paterson

, McGillivray

, et al. Further studies on the Chikungunya outbreak in Southern Rhodesia in 1962. I. Mosquitoes, wild primates and birds in relation to the epidemic. Ann Trop Med Parasitol, 1964; 58:45–51; doi: 10.1080/00034983.1964.11686213

84.

Montoya

, Rosso

. Diagnosis and management of toxoplasmosis. Clin Perinatol, 2005; 32(3):705–726; doi: 10.1016/j.clp.2005.04.011

85.

Morawakkorala

, Senarathana

AMRD

, De Alwis

ACD

, et al. Two cases of monkey tapeworm (Bertiella studeri) infestation from Sabaragamuwa Province. Sri Lanka J Child Health, 2008; 35(1):34–35; doi: 10.4038/sljch.v35i1.7

86.

Munasinghe

, Amarasekera

, Fernando

CFO

. An epidemic of dengue-like fever in Ceylon (chikungunya)-a clinical and haematological study. Ceylon Med J, 1966; 11(4):129–142.

87.

Muthugala

, Dheerasekara

, Harischandra

, et al. Hantavirus infection with pulmonary symptoms in north central part of Sri Lanka. J Clin Virol Plus, 2021; 1(4):100052; doi: 10.1016/j.jcvp.2021.100052

88.

Namusisi

, Mahero

, Travis

, et al. A descriptive study of zoonotic disease risk at the human-wildlife interface in a biodiversity hot spot in South Western Uganda. PLoS Negl Trop Dis, 2021; 15(1):e0008633; doi: 10.1371/journal.pntd.0008633

89.

Nanayakkara

, Rajapakse

RPVJ

, Wickramasinghe

, et al. Serological evidence for exposure of dogs to Rickettsia conorii, Rickettsia typhi, and Orientia tsutsugamushi in Sri Lanka. Vector Borne Zoonotic Dis, 2013; 13(8):545–549; doi: 10.1089/vbz.2012.1049

90.

Nanayakkara

, Smith

, Rupprecht

. Rabies in Sri Lanka: Splendid isolation. Emerg Infect Dis, 2003; 9(3):368–371; doi: 10.3201/eid0903.020545

91.

Niloofa

, Fernando

, de Silva

, et al. Diagnosis of leptospirosis: Comparison between microscopic agglutination test, IgM-ELISA and IgM rapid immunochromatography test. PLoS One, 2015; 10(6):e0129236; doi: 10.1371/journal.pone.0129236

92.

Niriella

, Ediriweera

, De Silva

, et al. Dengue and leptospirosis infection during the coronavirus 2019 outbreak in Sri Lanka. Trans R Soc Trop Med Hyg, 2021; 115(9):944–946; doi: 10.1093/trstmh/trab058

93.

Patabendige CGUA, Wimalaratne O, Rabies in mongooses and domestic rats in the Southern Province of Sri Lanka CMJ. 2003; 48(2): 48–50; doi: 10.4038/cmj.v48i2.3370

94.

Perera

, Chan

, Ma

, et al. Influenza virus infections among a sample of hospital attendees in Ragama, Sri Lanka. Ceylon Med J, 2010; 55(2):40–44; doi: 10.4038/cmj.v55i2.1987

95.

Perera

, Wickramasinghe

, Cheung

, et al. Swine influenza in Sri Lanka. Emerg Infect Dis, 2013; 19(3):481–484; doi: 10.3201/eid1903.120945

96.

Pradeepan

, Ketheesan

, Murugananthan

. Emerging scrub typhus infection in the northern region of Sri Lanka. BMC Res Notes, 2014; 7(1):719–714; doi: 10.1186/1756-0500-7-719

97.

Prasannath

. Trends and developments in Sri Lanka’s livestock industry. J Stud Management Planning, 2015; 1(4):46–55.

98.

Premaratna

, Loftis

, Chandrasena

TGAN

, et al. Rickettsial infections and their clinical presentations in the Western Province of Sri Lanka: A hospital—based study. Int J Infect Dis, 2008; 12(2):198–202; doi: 10.1016/j.ijid.2007.06.009

99.

Rahman

, Sobur

, Islam

, et al. Zoonotic diseases: Etiology, impact, and control. Microorganisms, 2020; 8(9):1405; doi: 10.3390/microorganisms8091405

100.

Reller

, Akoroda

, Nagahawatte

, et al. Chikungunya as a cause of acute febrile illness in southern Sri Lanka. PLoS One, 2013; 8(12):e82259; doi: 10.1371/journal.pone.0082259

101.

Rostami

, Riahi

, Gamble

, et al. Global prevalence of latent toxoplasmosis in pregnant women: A systematic review and meta-analysis. Clin Microbiol Infect, 2020; 26(6):673–683; doi: 10.1016/j.cmi.2020.01.008

102.

Sathiadas

, Mubarak

, Arulmoli

. Clinical manifestations and microbiology of Shigella diarrhoea in children admitted to Teaching Hospital, Jaffna, Sri Lanka. Sri Lankan J Infec Dis, 2016; 6(2):94; doi: 10.4038/sljid.v6i2.8110

103.

Sathiadas

, Mayoorathy

, Varuni

, et al. Study on the recent outbreak of typhus in Jaffna district. Proce Sri Lanka College Paediatricians . 16th Annual Scientific Congress, 2013;06. Available from: http://repo.jfn.ac.lk/med/handle/701/578.

104.

Schønning

, Phelps

, Warnasekara

, et al. A case–control study of environmental and occupational risks of leptospirosis in Sri Lanka. Ecohealth, 2019; 16(3):534–543; doi: 10.1007/s10393-019-01448-w

105.

Schuffenecker

, Iteman

, Michault

, et al. Genome microevolution of chikungunya viruses causing the Indian Ocean outbreak. PLoS Med, 2006; 3(7):e263; doi: 10.1371/journal.pmed.0030263

106.

Senevirathna

MMSC

, Dharmadasa

. Income diversification and household welfare in Sri Lanka. J Agri Value Addition, 2021; 4(1):1–22; doi: 10.4038/java.v4i1.87

107.

Singh

, Daneshvar

. Human infections and detection of Plasmodium knowlesi . Clin Microbiol Rev, 2013; 26(2):165–184; doi: 10.1128/CMR.00079-12

108.

Sinhabahu

, Perera

, Samarasinghe

, Nanayakkara

. A case of Hymenolepis diminuta (rat tape worm) infestation in a child. Ceylon Med J, 2014; 59(2):70–71; doi: 10.4038/cmj.v59i2.7070

109.

Sirisena

, Iddawela

WMDR

, Noordeen

, Wickramasinghe

. Prevalence and identification of Cryptosporidium species in paediatric patients with diarrhoea. Ceylon Med J, 2014; 59(3):75–78; doi: 10.4038/cmj.v59i3.7467

110.

Subasinghe

SDLP

, Karunaweera

, Kaluarachchi

. Toxoplasma gondii seroprevalence among two selected groups of women. Sri Lankan J Infect Dis, 2011; 1(1); doi: 10.4038/sljid.v1i1.3091

111.

Sunil-Chandra

, Jayaweera

JAAS

, Kumbukgolla

, et al. Association of hantavirus infections and leptospirosis with the occurrence of chronic kidney disease of uncertain etiology in the North Central Province of Sri Lanka: A prospective study with patients and healthy persons. Front Cell Infect Microbiol, 2020; 10:556737; doi: 10.3389/fcimb.2020.556737

112.

Tegner

, Sunil-Chandra

, Wijesooriya

, et al. Detection, identification, and antimicrobial susceptibility of Campylobacter spp. and Salmonella spp. from free-ranging nonhuman primates in Sri Lanka. J Wildl Dis, 2019; 55(4):879–884; doi: 10.7589/2018-08-199

113.

Torgerson

, Hagan

, Costa

, et al. Global burden of leptospirosis: Estimated in terms of disability adjusted life years. PLoS Negl Trop Dis, 2015; 9(10):e0004122; doi: 10.1371/journal.pntd.0004122

114.

Torgerson

, Pierpaolo

. The global burden of congenital toxoplasmosis: A systematic review. Bull World Health Organ, 2013; 91(7):501–508; doi: 10.2471/BLT.12.111732

115.

UNICEF. Budget Brief: Health Sector-Sri Lanka. 2021.

116.

Wang

, Lai

, Zhu

, et al. Human angiostrongyliasis. Lancet Infect Dis, 2008; 8(10):621–630; doi: 10.1016/S1473-3099(08)70229-9

117.

Warnasekara

, Srimantha

, Kappagoda

, et al. Diagnostic method-based underestimation of leptospirosis in clinical and research settings; an experience from a large prospective study in a high endemic setting. PLoS Negl Trop Dis, 2022; 16(4):e0010331; doi: 10.1371/journal.pntd.0010331

118.

Weerasooriya

WALK

, Rangana

, Iddawela

WMDR

, et al. 2020. Disseminated Cryptosporidium Parvum infection in a post renal transplant child. Sri Lanka J Medicine, 2020; 29(2); doi: 10.4038/sljm.v29i2.165

119.

Welgama

, Herath

, Gandhiji

. Hydatid cyst of the lung: A case report from Sri Lanka. Anuradhapura Med J, 2019; 13(1):18; doi: 10.4038/amj.v13i1.7650

120.

White

, Razgour

. Emerging zoonotic diseases originating in mammals: A systematic review of effects of anthropogenic land‐use change. Mamm Rev, 2020; 50(4):336–352; doi: 10.1111/mam.12201

121.

Wijesundera

, Ranaweera

. Case reports of Dipylidium caninum; a pet associated infection. Ceylon Med J, 1989; 34(1):27–30.

122.

Wijendra

WAS

, Kulathunga

KAKC

, Ramesh

.. First report of Listeria monocytogenes Serotypes detected from milk and milk products in Sri Lanka. Adv Anim Vet Sci, 2014; 2:(5S):11–16; doi: 10.1473/7/journal.aavs/2014/2.5s.11.16

123.

World Bank Data. 2022. Available from: https://data.worldbank.org/country/LK

124.

World Health Organization. 2020. Available from: https://www.who.int/news-room/fact-sheets/detail/zoonoses

125.

World Health Organization. Leptospirosis: Fact Sheet. 2009. Available from: https://www.who.int/publications/i/item/B4221.

126.

Yathramullage

, Meegaskumbura

. Leptospira reservoirs among small mammals in Sri Lanka. J Bacteriol Mycol, 2016; 3(4):1040.

127.

Zahedi

, Paparini

, Jian

, et al. Public health significance of zoonotic Cryptosporidium species in wildlife: Critical insights into better drinking water management. Int J Parasitol Parasites Wildl, 2016; 5(1):88–109; doi: 10.1016/j.ijppaw.2015.12.001

A Systematic Review of Zoonotic Disease Prevalence in Sri Lanka (2000–2022)

Abstract

Background:

Materials and Methods:

Results:

Conclusions:

Introduction

Materials and Methods

Systematic review protocol

Inclusion and exclusion criteria

Search strategy

Selection of studies and data extraction

Results

Database search and selection process

Distribution of selected studies

Bacterial zoonoses

Leptospirosis

Rickettsioses

Brucellosis

Q fever

Shigellosis, campylobacteriosis, salmonellosis, and listeriosis

Viral zoonoses

Hantavirus infection

Rabies

Influenza a

Japanese encephalitis

West Nile virus infection

Monkeypox

Chikungunya

Parasitic zoonoses

Protozoa

Toxoplasmosis

Giardiasis

Plasmodium knowlesi

Cryptosporidiosis

Nematodes

Brugian filariasis

Dirofilariasis

Toxocariasis

Angiostrongyliasis

Hookworms

Cestodes

Bertielliasis

Sparganosis

Zoonoses caused by other cestodes

Discussion

Conclusions

Footnotes

Author Disclosure Statement

Funding Information

References