A Parasitological Survey of Natural Water Springs and Inhabitants of a Tourist City in Southeastern Brazil

Abstract

The goals of this study were to investigate the occurrence of Cryptosporidium oocysts and Giardia cysts in main springs of Campos do Jordão, an important tourist city, in Brazil and to gather the largest amount of parasitological data from autochthonous population that live in rural areas of this city. The membrane filtration technique followed by direct immunofluorescence assay was employed for concentration and visualization of waterborne protozoa. In the period between June 2003 and May 2004, the presence of at least one pathogenic protozoa was detected in 25.0% (3/12) of the springs studied, with mean concentrations ranging from 0.2 to 0.3 Cryptosporidium sp. oocysts and 0.07 to 0.1 Giardia sp. cysts/L. The coproparasitological investigation conducted in dwellers from two rural communities from this city revealed that 49.2% (91/185) of people had intestinal parasites. Among pathogenic protozoa, Cryptosporidium was the most prevalent species (8.1%) followed by Giardia duodenalis (5.9%), Entamoeba histolytica/Entamoeba dispar (2.7%), and Blastocystis hominis (2.2%). The most prevalent geohelminths were Ascaris lumbricoides (14.9%) and Trichuris trichiura (9.7%). This study demonstrated the contamination and the distribution of intestinal parasites, especially Cryptosporidium and Giardia species, in different springs of an important tourist city in Brazil, highlighting the need of monitoring natural water sources. The high prevalence of intestinal parasitosis detected in some specific populations of this city may function as a link of transmission of different intestinal parasitosis due to soil and water contamination, contributing to the maintenance of parasite life cycles. Therefore, the inclusion of consistent public health interventions with measures that include the protection of springs, the installation of minimum health infrastructure, and primary education of the population are widely necessary, aiming the control and prevention of parasite infections.

Introduction

P eople living in poverty throughout the developing world are heavily burdened with neglected communicable diseases, particularly parasitic diseases (Ehrenberg and Ault 2005). Some of these neglected diseases may have parasitic origin that includes soil-transmitted helminthiasis, schistosomiasis, and parasitic zoonoses such as cryptosporidiosis and giardiasis (Savioli et al. 2006).

Cryptosporidium and Giardia species are recognized worldwide as important causative agents of diarrhea in children and adults. The burden of these enteric protozoa continues to fall heavily on developing regions, where infection is ubiquitous and often presents more severe clinical consequences, also represents an important public health problem in developed countries (Smith et al. 2007).

In developing countries, cryptosporidiosis and giardiasis are mostly seen during early childhood, where children under 2 years of age are naturally more susceptible to parasitism. These protozoans, as well as the consequences derived from the parasitism, might be responsible for childhood malnutrition and have been linked to impaired physical growth and deficiencies in cognitive development in late childhood (Ortega-Pierres et al. 2009).

Although cryptosporidiosis is self-limiting in healthy human adults, the infection might be life threatening for those unable to mount an adequate immune response such as children, the elderly, and also immunocompromised patients (Chalmers and Davies 2010). Nowadays Cryptosporidium and cryptosporidiosis have been reported in all continents, including Antarctica (Fredres et al. 2008).

In recent times, giardiasis is considered as a re-emergent parasitosis due to, among other factors, its increased prevalence in children, especially those who attend day care centers, being responsible for an important morbidity in childhood (Thompson 2000).

Transmission routes of Cryptosporidium and Giardia infections include direct human to human contact, animal to human contact, ingestion of contaminated food, and there is a concern that water is the main source of infection, where numerous waterborne outbreaks were extensively documented worldwide (Smith and Nichols 2010). The persistence of cysts and oocysts in different aquatic environments, their ability to survive the disinfection procedures, and the low infection dose are some factors that favor its waterborne transmission and also make their control a real challenge for public health authorities (Slifko et al. 2000).

While the majority of the Brazilian urban population has acquired access to running water and sewage systems (Barcellos 2005), a huge paradox is observed in the periurban and rural areas, where low-income populations are characterized by poor standards of life due to the lack of infrastructure and sanitation. This situation may be observed even in the richest cities, almost always on the periphery of these sites.

Campos do Jordão is a thriving city that attracts many visitors every year because of its great potential for ecotourism. The tourists are attracted to this city due to its climate and very low temperatures in the colder seasons of the year, typically during the Brazilian winter and also because the city harbors various natural mineral water springs that are consumed by visitors and local population. In 2002–2003 an outbreak of hepatitis A occurred in the town of Campos do Jordão (César and Bassit 2004) and microbiological monitoring revealed that almost 60.0% (13 of a total of 22 springs) were not in accordance with the Brazilian legislation of National Agency of Sanitary Surveillance (ANVISA) for drinking water destined for human consumption (Brazil 2005).

Considering that the dwellers of this city use natural spring waters for drinking and for cooking purposes, the goals of this study were to investigate the occurrence of Cryptosporidium and Giardia (oo)cysts in water samples of main springs from Campos do Jordão, an important tourist city, located in Southeastern Brazil and to gather the largest amount of parasitological data from the autochthonous population that live in rural areas of the city.

Materials and Methods

Study design

The city of Campos do Jordão is located in northeastern of São Paulo state, in a nature reserve (22°44′22′′W, 45°35′29′′S). In mountainous regions, poor settlements and luxury residences share contiguous neighborhoods. A great wooded area covers a large portion of the hills, where numerous small water springs (n=42) are located.

Samples of natural water from 12 springs (6 from urban areas and 6 from rural areas) (Fig. 1) were collected bimonthly, during the whole period of the study (1 year), in three strategic occasions: (i) high season (from June to September), (ii) the wettest months (from October to January), and (iii) the driest months (February to May). Different springs from urban and rural areas were selected to analysis according to previous observations of the neighborhoods, including information presented in an inventory of the natural springs as follows: (i) consumption of spring water by local population; (ii) previous history of fecal contamination (total and thermotolerant coliforms) in the last 12 months that preceded this study; (iii) potential risk of domestic animals or human fecal contamination; and 4, proximity to in natura sewage discharge sites and close to dumps or garbage.

FIG. 1.

Water springs sampling sites from Campos do Jordão city, São Paulo, Brazil. Color images available online at www.liebertonline.com/vbz

Site visits

On visits to water spring sources, some irregularities and lack of hygiene in some fountains utilized as drinking water were noted. The concrete cover from spring 8 was in a poor state and showed visible holes. Evidence of recent human excreta was in direct contact with the housing covers of the spring 7 reservation chambers. In addition, manure was also present in a field around spring 10. In the case of some springs located in the urban area (1, 3, 6), garbage was observed near the water. The springs 4, 5, and 7 are located in the tourist/commercial area of the city and its fountains are reasonably well preserved. In rural areas, the water that flows from the fountains inside the forest is driven by precarious plumbing into the woods and stored in tanks where, during the rainy season, it is covered by the floodwater that comes down the hills. The spring 11 is located in an area of reforestation and at spring 12, the water flows directly through the rocks.

Parasitological examination of spring water samples

Samples were collected in sterile 20-L containers and were immediately stored and transported under refrigerated conditions to the laboratory. For parasitological analysis, water samples were submitted to membrane filtration (47-mm-diameter sterile cellulose esters membranes) (Millipore^®), with nominal porosity of 3 μm. Afterward, sample elution was performed by alternatively scraping the membrane with a smooth-edged plastic loop and rinsing it with 0.1% Tween 80 elution solution; the pellets were obtained by two centrifugation steps (1050 g; 15 min) and diluted with a 1 mL of Milli Q water (Millipore^®). Aliquots of all pellets were examined by dual staining with monoclonal antibodies (Merifluor^® kit; Meridian, Bioscience) and the vital dye DAPI. The specimens were simultaneously confirmed using a phase-contrast microscopy to evaluate specific structures of both protozoans in accordance with criteria stipulated by the United States Environmental Protection Agency (USEPA 2005).

Control test experiments

To assess the recovery efficiency of the method utilized, triplicate control experiments were performed in accordance with Cantusio Neto and Franco (2004). Briefly, the suspension of positive control from Merifluor Kit was used in control test experiments and diluted in sterile phosphate-buffered saline (1:10). Three aliquots of 5 μL of this suspension were counted directly from the immunofluorescence well slides, where the mean number of (oo)cysts obtained was calculated. The following mean concentrations of protozoa (85.1 oocysts/L and 11.5 cysts/L) were inoculated into 20 L of Milli Q water. After this, contaminated samples were analyzed using the same filtration and visualization methods described in “Parasitological examination of spring water samples” section. The sensitivity of methodology was estimated based on the mean number of oocysts and cysts recovered in the control experiments, driven in triplicate and according to the following equation:

X=R/S where:

X=recovery efficiency

R=number of (oo)cysts recovered

S=number of (oo)cysts seeded

For the negative-control experiments (n=6), a sample of 20 L Milli Q water was used. The same laboratory procedures were applied as described previously.

Coproparasitological diagnosis

This project received the approval of the Ethics Committee from Campinas State University (no. 193/2006). The participants only became involved in our research after individual agreement on participating in this study. An informed consent was given to all the persons at a meeting concerning the study. Consent was also obtained from guardians and/or parents of children and persons younger than 18 years of age. In addition, each individual was only included in the epidemiological study after filling in a questionnaire and after at least three fecal samples collected.

A total of 185 persons (from 0 to 71 years old) participated in the present study. The whole studied population belonged to two different neighborhoods located in the rural area, where the lack of health and sanitary infrastructure was observed. Further, the water supply is guaranteed by two natural water springs (enumerated in this study as number 8 and 10).

For screening intestinal parasites, four fecal samples were collected from each person during seven successive alternate days in plastic screw-capped recipients. Fresh stool samples were examined microscopically for the presence of intestinal parasites using the Kato-Katz method (OMS 1992). The Kato slides were examined qualitatively by skilled technicians within 30 days of collection. The other three fecal samples were fixed in 10% (v/v) formalin. The modified sedimentation methods of Ritchie as well as the flotation procedures of Willis and Faust, together with the spontaneous sedimentation method, were used for the coproparasitological analysis.

In the modified Ritchie method, the fecal homogenates were centrifuged at 500×g for 10 min following one ether-agitation step (30 s) and the sediment was submitted to the modified Ziehl-Neelsen staining according to Henriksen and Pohlenz (1981) using an alcohol-acid acetic solution as a decolorant agent instead of sulfuric acid.

Socioenvironmental data

The parents or guardians of children were interviewed by means of a structured questionnaire to evaluate several socioenvironmental characteristics and measure housing variables through information regarding the structural qualities and family characteristics (Table 1).

Table 1.

Household Survey Information Collected by Means of a Structured Questionnaire from Two Rural Neighborhoods (n=185 Dwellers) of Campos do Jordão city, São Paulo, Brazil

Variable	%	(No./total no. of persons)	p (chi-square)
Sex
Male	38.8	(71/183^a)	0.453
Female	61.2	(112/183)
Household income (minimum wage [MW])
1 MW	30.6	(37/121)	0.073^b
>1 MW	69.4	(84/121)
Mother's education
Elementary	80.8	(63/78)	0.092^b
Other levels of instruction	19.2	(15/78)
Home structure
Wood-home	54.9	(84/153)	0.273
Brick-home	45.1	(69/153)
Bathroom inside the house	90.1	(137/152)	0.665
Bathroom outside the house	9.9	(15/152)
Persons in each house
Three or more	59.5	(91/153)	0.325
Less than three	40.5	(62/153)
Presence of domestic animals
Yes	92.8	(142/153)	0.146
No	7.2	(11/153)
Children and contact with animals
Yes	77.5	(117/151)	0.865
No	22.5	(34/151)
Main source of drinking water
Springs	96.0	(145/151)	0.074^b
Public system	4.0	(6/151)
Habits before water consumption
Filtration, boiled water, or both	83.7	(113/135)	0.006^b
Consumption in natura	16.3	(22/135)
Wastewater disposal
In natura–bodies of water	45.8	(70/153)	0.547
Septic tanks	54.2	(83/153)
Contact with earth/sand
Yes	47.4	(64/135)	0.441
No	52.6	(71/135)
Wearing shoes
Yes	65.4	(87/133)	0.950
No	34.6	(46/133)

Two data were missing.

Significant at 10% level.

Statistical analysis

All parasitological data were statistically examined through specific tests. The Pearson chi-square test was used to verify the association between the parasitism and the variables of the study with significance of 10%. The Student's t-test was used to compare proportions, and the analysis of variance was used to compare the parasitism rate between different age groups using the statistical software SPSS version 12.0.

Results

Occurrence of protozoa in water springs

Campos do Jordão possesses a total of 42 water springs and 12 of them (28.6%) were included in the study according to previously established criteria. A total of 72 samples (20-L grab samples) were analyzed. The presence of at least one waterborne protozoan was detected in 25.0% (3/12) of the water springs analyzed (Table 2). Cryptosporidium oocysts and Giardia cysts were identified in water samples taken from urban area (springs 1 and 7) at a concentration of 0.3 oocysts and 0.07 cysts/L, respectively. Further, both protozoa were registered at spring 2 (rural area) with a concentration of 0.2 oocysts/L and 0.1 cysts/L. The overall positivity rate was 33.3% (2/6) for the springs located in the urban area while the contamination by protozoa was found in 16.7% (1/6) of springs located in the rural area.

Table 2.

Occurrence of Cryptosporidium and Giardia (Oo)cysts in 12 Natural Water Springs Harvested Bimonthly During 1 Year in Campos do Jordão, São Paulo, Brazil

	Seasons of water sampling
	1 (High season)		2 (Wettest season)		3 (Driest season)
Springs	Jun–Jul	Aug–Sep	Oct–Nov	Dec–Jan	Feb–Mar	Apr–May
1	A	A	A	A	A	C+
2	C+	A	A	A	A	G+
3	A	A	A	A	A	A
4	A	A	A	A	A	A
5	A	A	A	A	A	A
6	A	A	A	A	A	A
7	A	G+	A	A	A	A
8	A	A	A	A	A	A
9	A	A	A	A	A	A
10	A	A	A	A	A	A
11	A	A	A	A	A	A
12	A	A	A	A	A	A

C+, positive for Cryptosporidium oocysts; G+, positive for Giardia cysts; A, absence of pathogenic protozoa.

Sensitivity of methodology

The mean recovery efficiency found in the control experiments was 70.9% for Cryptosporidium oocysts and 48.3% for Giardia cysts. Cysts and oocysts were not detected in the negative control experiments.

Coproparasitological inquiry

The overall prevalence of intestinal parasites observed in the studied population was 49.2% (91/185) (Table 3). Considering all fecal samples, which were tested positive, intestinal protozoa were detected in 35.7% (66/185) of the participants, while the infection by helminths was found in 22.2% (41/185) individuals. A concomitant infection of protozoa and helminths was observed in 8.65% (16/185) of the persons. Coinfections reached a maximum of six different species.

Table 3.

Prevalence of Parasite Species in the Fecal Parasitological Inquiry of Dwellers (n=185) from Two Rural Neighborhoods of Campos do Jordão city, Sao Paulo State, Brazil

Parasite	Number of parasitized individuals	%
Protozoa
Entamoeba coli	36	19.5
Cryptosporidium spp.	15	8.1
Giardia duodenalis	11	5.9
Iodamoeba. bütschlii	8	4.3
Entamoeba histolytica/E. dispar	5	2.7
Blastocystis hominis	4	2.2
Endolimax nana	1	0.5
Helminths
Ascaris lumbricoides	27	14.9
Trichuris trichiura	18	9.7
Hookworms	2	1.1
Taenia sp.	2	1.1
Enterobius vermicularis	2	1.1
Larvae of nematode	2	1.1
Monoparasited	62	68.0
Polyparasited	29	32.0
Total	91	49.2

Infections caused only by protozoa were observed in 27% (50/185) of the persons and 13.5% (25/185) presented only geohelminths and these differences were not statistically significant (chi-square: 0.257, p=0.612). Among protozoa, the most prevalent species were Entamoeba coli, Cryptosporidium sp., Giardia duodenalis, Iodamoeba bütschlii, and Entamoeba histolytica/E. dispar. Blastocystis hominis and Endolimax nana were present in lower concentrations (2.2 and 0.5, respectively) (Table 3). Among helminth infections, the most prevalent species were Ascaris lumbricoides and Trichuris trichiura, while hookworms, Taenia sp., Enterobius vermicularis and larvae of nematodes were detected in lower concentrations (Table 3).

The polyparasitism was present in 15.7% (29/185) of the studied population while the prevalence rate of monoparasitism was 33.5% (62/185). No statistical difference was found between the parasitism in males and females (chi-square: 0.562, p=0.453); parasites were found in 52.1% (37/71) of males and in 46.4% (52/112) of females.

When comparing the prevalence of intestinal parasites among different age groups (Table 4), the results obtained by analysis of variance showed no statistically significant differences (F=1.438, p=0.213).

Table 4.

Prevalence of Intestinal Protozoa and Helminths Observed on Parasitological Inquiry in Different Age Groups from Rural Autochthonous Population of Campos do Jordão, São Paulo State, Brazil

Protozoa (%)
Age groups	Cryptosporidium sp.	Giardia sp.	E. histolytica	B. hominis	E. coli	I. bütschlii	E. nana
0–12	4.3	4.3	0.5	1.1	14.6	3.2	0.5
13–24	0.5	0	0.0	0	1.6	0	0
25–36	2.2	0	0	0	1.6	0	0
37–48	0.5	0.5	1.1	0.5	2.2	0	0
49–60	0.5	0	0	0	0	0	0
61–72	0.0	0	0.5	0	1.1	0	0

Helminths (%)
Age groups	A. lumbricoides	T. trichiura	Taenia sp.	Hookworms	E. vermicularis	Larvae of nematoda
0–12	9.7	5.9	0.0	1.1	0.5	0.0
13–24	2.7	2.2	0	0	0	0
25–36	1.1	0	1.1	0	0	0
37–48	1.1	0	0	0	0.5	4.3
49–60	0	0	0	0	0	0
61–72	0	0	0	0	0	0

Regarding the socioeconomic and cultural evaluation, it was observed that 69.4% (84/121) of households had income below the minimum wage and did not have health facilities and treated water.

Discussion

Water is a limited natural resource and fundamental to life and health (UNICEF 2010). The consumption of groundwater may be a substitute to drinking water when water supplied by companies is not available. In Brazil, consumption of groundwater is somewhat common and this fact is supported by economic and cultural reasons. Further, in rural areas, it may be the only drinking water source available to the population.

The groundwater may be prone to contamination by protozoa or other pathogenic microorganisms, and, to a lesser extent, to the surface waters because the layers of soil and rocks function as a natural barrier to microorganisms. However, the contamination of water originated from springs and wells is strongly influenced by surface waters and other factors of environmental contamination such as sewage, septic tanks, animal feces, and garbage (Moulton-Hancock et al. 2000).

The presence of pathogenic protozoa in 25.0% (3/12) of the spring waters examined in this study is relevant from the standpoint of public health because local population and tourists visit Campos do Jordão to drink natural spring waters. In the United States, oocysts were detected in 20.0% (7/35) and 5.0% (7/149) of springs and wells, respectively, while Giardia cysts were present in 14.0% (5/35) of the springs and 1.0% (2/149) of the wells (Hancock et al. 1998). In Brazil, Nishi et al. (2009) detected Cryptosporidium oocysts in 14.3% (1/7) of springs analyzed (mean concentration of 6.0 oocysts/L). All in all these data show that springs are more vulnerable to contamination by pathogenic protozoa than wells, since springs may be in contact with several sources of contamination originated from the soil surface.

In this study, we observed similar frequency among the findings of Cryptosporidium and Giardia (oo)cysts in Campos do Jordão springs. Water availability and environmental conditions like topography and soil porosity as well as the presence of sewers, septic tanks, and pasture areas near the springs might have contributed to the occurrence of both protozoa in several water springs. Moreover, it was verified that there is a fast growing urban sprawl in the hilly areas of this city, where many water springs are located and these springs may be contaminated by human or animal fecal wastes.

The density of cysts (0.07–0.1/L) and oocysts (0.1–0.3/L) detected in this study is of great importance concerning public health, considering that the ingestion of low doses of infective (oo)cysts may establish an infection in individuals with disabilities in the immune system or those suffering from malnutrition (Chalmers and Davies 2010) if they are found to be infectious to humans. Further analysis must be done using specific techniques such as molecular assays aimed at the comprehension of the sources of fecal contamination of natural water springs.

Among the positive springs, the presence of pathogenic protozoa was detected twice on spring 2; this spring is located in the rural area and the reservation box was not built according to recommended standards (edges of 30 cm above the floor) and it remains under the influence of run-off. Previous microbiological data analysis showed positive results for spring 2 with significant values for total coliforms (>2419.2 MPN/100 mL) and for thermotolerant coliforms (45.0 MPN/100 mL) (SABESP 2002).

These findings and the recent occurrence of an outbreak of hepatitis A in the population of Campos do Jordão city denotes the vulnerability of springs to contamination, water pollution in this city, and a risk of acquiring human enteropathogens through its consumption. It is important to emphasize that some springs, especially those located in lowlands and others surrounded by houses without sanitation, were closed by municipal sanitary authorities but the persons have resumed consuming water from these sources.

The results of control experiments ensured the reliability of the methodology used for the detection of protozoa in water samples: the efficiency of recovery was 70.9% for Cryptosporidium and 48.3% for Giardia sp. Similar results were obtained by Franco and Cantusio Neto (2002) when employing the same protocol (membrane filtration) to detect the presence of oocysts in samples of bottled mineral waters marketed in Campinas, São Paulo State, Brazil, where densities of oocysts ranged between 0.2 and 0.5 oocysts/L. Thus, the absence of protozoa in some of the springs studied does not imply any deficiency in the methodology; one should point out the intermittency of oocysts and cysts in the environment.

We detected the presence of protozoa in 33.3% (2/6) of the springs located in the urban area suggesting that they are more prone to contamination by protozoa since they are under the influence of domestic sewage and septic tanks and there is no restriction of access of people and animals to springs and to water-harvesting sites. The lack of potable water and sanitary conditions may have contributed to the contamination of persons living in two rural communities of Campos do Jordão city, considering the high prevalence of intestinal parasites observed in the population (49.2%, 91/185) (Table 3).

Lura et al. (2000) conducted a study of prevalence of intestinal parasites in children under 12 years of age who have drunk water from the subsoil origin and reported that 47.0% to 67.0% of children harbored enteric parasites. These authors established a relationship between socioeconomic levels and frequency of intestinal parasitism, and found that the positivity was higher in people from lower socioeconomic backgrounds. Similar findings were observed in our study, where the families which received lower income (one minimum wage) (30.6%, 37/121) were more prone to intestinal parasitic infections (p=0.073) (Table 1). Mother's education, that is, those who only had the elementary degree of study (80.8%, 63/78), was also considered an important factor related with a higher level of parasitic infections in both communities studied (p=0.092).

In this study, 96.0% (145/151) of people used the springs from rural area as the main source of drinking water and 16.3% (22/135) consumed the water directly from the springs (in natura) (Table 1). It should be noted that consumption of filtered and boiled water of spring origin was reported only by 1.6% (2/135) of persons who participated in this parasitological survey; however, 83.7% (113/135) of people had the habit of filtering or boiling the spring water before consumption. It was also verified that there was a significant association between filtering and boiling the water and a lower incidence of positive parasite exams in the studied population (p=0.006) (Table 1).

Among pathogenic protozoa, Cryptosporidium sp. was the most common intestinal one (8.1%) detected in this investigation, where 53.3% of parasitized individuals were children, followed by G. duodenalis (5.9%) and E. histolytica/E. dispar (2.7%). The prevalence of B. hominis was 2.2%, although the real significance of this finding, as well as the pathogenic potential of this species in immunocompetent hosts, is still controversial (Mendoza et al. 2001).

Among the nonpathogenic species of protozoa, the most frequent in this study was E. coli (19.5%), followed by I. büetschlii (4.3%) and E. nana (0.5%), which further emphasizes that the hygienic and sanitary conditions of people are not appropriate. Therefore, the prevalence of those pathogenic protozoa, together with the fecal-orally transmitted commensals, can be considered as the bioindicators of the low socioenvironmental conditions and quality of life of this population.

Geohelminth infections flourish in impoverished areas characterized by inadequate sanitation and overcrowding. Chronic and massive geohelminth infections lead to malnutrition and iron deficiency anemia and also adversely affect physical and mental growth in children (Hotez et al. 2008).

In fact, the urban sprawl and lack of basic sanitation infrastructure are features of the two rural neighborhoods analyzed in this study and such conditions also contribute to the occurrence and spread of intestinal helminthiasis which are closely related to soil humidity and proximity to bodies of water (Brooker et al. 2009).

The factors listed above, combined with environmental and climate conditions of Campos do Jordão, that is, temperate climate with wet and mild summers, also favor the long-term survival of helminth eggs in soil and thus may explain the high prevalence of A. lumbricoides (14.9%; 27/185) and T. trichiura (9.7%, 18/185) found in persons from the rural area in this study.

Ferreira et al. (2000) when analyzing the secular trend of intestinal parasitosis, highlighted that giardiasis, ascariasis, and trichuriasis predominate over the other intestinal parasitosis in children in Brazil.

Mortean et al. (2010) analyzed the occurrence of intestinal parasites in rural communities of the state of Paraná, Brazil, in 2003–2004, and found that the overall prevalence of intestinal parasites was 19.8% (1033/5219). The most prevalent parasite was E. coli (7.2%, 376/5219) followed by G. duodenalis (5.2%, 272/5219). Cryptosporidium analysis was not performed. A lower prevalence of intestinal helminthes such as A. lumbricoides (0.8%, 42/5219) and T. trichiura (0.5%, 26/5219) was also observed. Saldiva et al. (1999) investigated the occurrence of intestinal parasites in children aged between 1 and 12 years old who live in 3 rural communities of a city located in the countryside of São Paulo state and confirmed that G. duodenalis (44.5%, 231/520), T. trichiura (40.1%, 208/520), and A. lumbricoides (32.5%, 169/520) were the most commonly detected parasites.

Also, it should be emphasized that in this study it was not possible to apply the quantitative Kato-Katz technique because a huge number of helminth eggs were found in these samples, which denotes that these children had massive infections. In these conditions, it is necessary to consider the possible negative effects derived from massive helminth infections in children's health such as susceptibility to other infections, interference in vaccine efficacy, and immune-mediated processes as allergy (van Riet et al. 2007). Although we did not utilize a specific technique to perform the detection of eggs of E. vermicularis, the occurrence of these helminth eggs in feces reinforces that people of these rural neighborhoods lack basic hygiene and important heath facilities. This study also showed that children and adults of both sexes were equally exposed to several risk factors for the acquisition of parasitic infections since there was no statistical significance (p=0.653) related to age or sex and parasitism.

In summary, parasitized children can suffer adverse effects on health exhibiting short-height-for-age, cognitive deficits, and lower performances at school as well as considerable morbidity in adults. The high prevalence of intestinal parasites prevailing in these rural communities may contribute to waterborne transmission of infective forms of protozoa and also the spread and maturation of helminth eggs in the environment. Further, the analysis of fecal samples from domestic animals (dogs and cats) that live in these rural communities would help to elucidate its epidemiological importance as a source of infection and contamination for humans and water springs, respectively.

Therefore, field research involving theses communities and the natural sources of water consumed by local and tourist populations is needed. Moreover, our findings must be interpreted to guide municipal public health interventions such as (i) satisfactory management and protection of spring water sources; (ii) improvement or installation of minimum health structures and basic sanitation, especially in the rural areas, with active participation of the city government; and (iii) primary education for children and adults regarding the modes of transmission and the prevention of intestinal parasites.

Footnotes

Disclosure Statement

No competing financial interests exist.

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