A multifactorial strategy for dengue prevention and control: A public health situation analysis

Dengue is the most widespread mosquito-borne flavivirus infection transmitted by Aedes mosquitoes. It is one of the greatest challenges to public health with a substantial economic burden in countries with tropical or subtropical climates. ¹ Over the past few decades, there has been a dramatic increase in the frequency of epidemics and severe dengue disease. ² Global surveillance estimates reveal that dengue affects 400 million people and results in over 20,000 deaths annually. ³ The rise in ambient temperature as a result of climate change, unplanned rapid urbanisation, extensive geographic distribution of Aedes mosquitoes, unabated population growth, ecological conditions favouring mosquito breeding, and weak surveillance systems have collectively made dengue to be one of the most pressing health threats. ⁴ A more worrying outlook is shown as presently no specific antiviral therapies are available for treatment and supportive care management of dengue patients. ⁵ Mosquito vector control remains a key strategy to curtail the transmission and intensification of dengue. ⁶ This commentary presents a concise yet comprehensive summary of factors driving the transmission of dengue, challenges associated with the current community-based interventions, and approaches to effective prevention and control.

Dengue transmission dynamics are complex and have been impacted by local knowledge, attitudes, and behaviour that are largely affected by factors in relation to demographic, health, societal, economic, environmental, and political spheres.^7,8 Many dengue-endemic zones are in low-income and middle-income countries that face a myriad of constraints ascribable to fragile healthcare delivery systems and sparse human and financial resources to implement vector control and prevention strategies. ⁹ Current healthcare modalities are fragmented, uncoordinated, and unsustainable, and are blighted by rising healthcare costs and poor health systems and security.^10–12 There is a lack of emerging preventive care systems that focus on population health and connect to strong and readily accessible primary and community care, where multidisciplinary teams can work together on all health-related issues.^11–13 The current healthcare delivery model also does not capture infected individuals who are asymptomatic or develop only very minor symptoms, contributing to a silent infectious reservoir in the dynamics of persistent transmission in areas that have competent mosquito vectors and conducive climatic conditions. ¹²

Although a dengue vaccine has been approved worldwide, many low-income countries with a consistently high dengue burden encounter numerous constraints owing to poorly resourced and understaffed organisation in the delivery of health services, thus limiting their capacity to administer the vaccine to their populations.^9,14 Such a situation is further plagued with pressures to provide universal health coverage, unavailability of integrated management tools, deficiencies of entomological expertise and understanding of critical epidemiological aspects of the disease, difficulties to distribute pre-vaccination screening test kits and vaccines to hard-to-reach rural and urban areas, as well as narrow age groups who are suitable for the dengue vaccine.^9,15–17 The scarcity of quality research for more effective and timely solutions, as well as inadequate healthcare initiatives to combine various interventions known to be effective against other mosquito-borne diseases, including rapid diagnostic methods, vaccination strategies, immunological markers, environmental determinants, and vector control measures, are underlying causes of the failure in curbing dengue expansion. ¹⁷ Moreover, competing priorities in the governance of health cause policy makers to align varied priorities for Aedes-transmitted viral diseases, resulting in diminished governmental, financial, and institutional support for continuity of programmes and practices directed towards long-term sustainable prevention and control of dengue virus. ⁸

The burden of dengue has been highly concentrated in Southeast Asia and Latin America for many years, posing significant infection risks to all the populations and age groups. ¹⁸ The morbidity and mortality associated with it have been considerable. ¹⁹ In particular, children and adolescents 10–19 years of age are most susceptible to a severe disease trajectory. ⁵ Participatory community engagement and health-seeking behaviour are essential in the vigorous response necessary to avoid the proliferation of mosquito-breeding habitats and the risk of dengue transmission. ¹² Community-based interventions that encompass entomological surveillance and evidence-based, active participation of affected populations have depicted benefits in improving knowledge, reducing household-level entomological indices, and decreasing incidence of dengue. To achieve effective and sustainable vector control and prevention efforts, it is indispensable to understand the needs of diverse populations and their lived experiences, address inappropriate societal practices and behaviour, organise communication campaigns during inter-epidemic periods to sensitise communities in high-risk locations, and consolidate political commitment, goodwill, and community engagement across all segments. ²⁰

Existing literature has demonstrated that the risk of dengue transmission is correlated with low socio-economic status, low income, and low educational level, low literacy, limited knowledge about the disease, the presence of economically inactive people in the household, including unemployed, students, and house workers, household crowding, substandard housing such as inadequate sewage and garbage disposal, lack of mosquito screening, and unavailability of air-conditioning system, as well as house type.^21,22 In light of the range of factors resulting in an increased frequency of dengue outbreaks, a holistic place-based approach is touted as an important ground for addressing the complex causal pathway of local dengue transmission and providing healthcare support to places of socio-economic deprivation where the inhabitants have poor health literacy and lack access to health services. Environmental and socio-economic indicators are suggested to play a significant role in modulating the risk of dengue disease. ²³

Hence, the implementation of dengue prevention and control interventions (Figure 1) should involve key stakeholders such as the federal government, state government, local government, public health officials, healthcare leaders, policy makers, clinicians, nurses, pharmacists, non-governmental community organisations, colleges, schools, leadership teams in business and industrial sectors, and non-chemical and chemical vector control personnels.^16,24 Furthermore, personal health beliefs and dengue-related knowledge, attitudes, and practices have implications for health behaviour and lifestyle changes which may ultimately reduce mosquito breeding sites and provide synergistic effect on mitigating dengue transmission.^25,26 Long-term sustainable interventional strategy necessitates active community involvement and stakeholder engagement.^27,28 Previous studies have suggested that core elements of the interventions encompass discussion with relevant stakeholders to set up a local steering committee comprised of epidemiologists, entomologists, ecologists, social scientists, and educational professionals, formation of working groups at grassroots level to promote community participation in environmental management, establishment of effective collaborations between community working groups, health services, and the government sectors, as well as integration of the interventional programme into national or regional vector control action plan. ²⁷ Specific public health measures include performing large-scale dengue surveillance testing in tandem with community-based environmental management (e.g. larviciding and adulticiding), deploying geospatial analysis and risk mapping technique to assess the risk of outbreaks in susceptible zones, analysis of trend and dengue virus evolution pattern over geographic location and duration of outbreaks, conducting epidemiological and entomological monitoring, and using low-cost and effective diagnostic bioassay for early detection of dengue, especially in resource-constrained and rural settings.^8,16,29

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Figure 1.

An overview of the factors contributing to the emergence of dengue outbreaks, essential components of community-based dengue prevention and vector control interventions, and key stakeholders involved in establishing and implementing community engagement programmes.

It is of paramount importance to decipher the facilitators and barriers associated with the implementation of vector control programmes in diverse communities. The main facilitating factors identified in previous research comprise door-to-door or mass media anti-dengue campaigning to educate the public, inspection of premises, mass home fumigation, ³⁰ indoor residual spraying, peri-domestic residual spraying,^31,32 housing improvement to limit indoor vector abundance,^33,34 incentivised community-based awareness and education outreach activities, increased allocations for water security and infrastructure, ³⁵ free distribution of larvicides, ³⁶ tariff exemption on vector control products, ³⁷ and local regulatory and legislative requirements for dengue vector control. ³⁸ However, it is often challenging to glean full engagement from the general public. Additionally, monitoring and responding to dengue epidemics is invariably hampered by a weak surveillance system, lack of essential geographic information, and scarce health resources. ³⁹ Other factors hindering vector control interventions include sparsity of advocates, lack of universal access to piped water resulting in the utilisation of improvised stored water which is a potential mosquito breeding site, wearing of short-sleeved shirts and short pants in tropical or subtropical environment, ³⁶ low priority given by governments and policy makers, ⁴⁰ and inadequate political commitment and financial resources to sustain meaningful community engagement.^8,41 Existing research has also found a lack of self-efficacy in undertaking preventive measures, a lack of perceived benefit from practising continuous dengue prevention strategies, and an underestimated perceived vulnerability of being infected with dengue. Of major public health concern, many people hold false beliefs that older people are less likely to be infected as their thickened and hardened skin is a natural defense against mosquito bites. Likewise, younger populations feel that their odds of getting dengue infection are low because of their strong immune system. There are also general common views that complementary and alternative medicine, for instance, carbonated isotonic sports drink, mixed vegetable and fruit juice, Carica Papaya leaf extract, bitter gourd juice, watermelon juice, porcupine gallstone, frog soup, and crab soup can cure dengue. ⁴² The pervasiveness of health misinformation and disinformation circulating on the community and social media negatively impacts decision making regarding health issues,^43–45 thereby influencing acceptability, adoption, penetration, and sustainability of dengue control interventions in the public.

Thus far, little is known about the public health impact of large-scale, rigorously implemented dengue vector preventive interventions involving effective collaboration between many imperative stakeholders in the society and intersectoral coordination with control activities at national, provincial, and district levels. ¹⁰ Important knowledge gaps continue to exist for identifying the appropriate intervention components that can be matched with the public healthcare infrastructure in dengue-endemic countries, most of which have been resource poor and less developed. In this regard, the World Health Organisation plays a role in coordinating global response and providing technical support for the development of sustainable, resilient, country-specific preventive measures. ⁴⁶ While less attention has been devoted to dengue in view of a lower mortality rate compared to other tropical diseases, ⁴⁷ an improved research capacity is warranted to uncover the most salient environmental, social, interpersonal, and behavioural factors to aid in the formulation of optimal preventive strategies for this environmentally-transmitted infectious disease which lacks a broadly indicated vaccine. There is also a crucial need for a nuanced understanding of the effective methods of communicating public health information to the population as a whole, tailoring public health messages that can be accepted by population subgroups of different socio-demographic characteristics, translating environmental interventions that have shown promising outcomes in decreasing vector densities into real-world practice, and evaluating implementation fidelity and adaptation of novel multi-faceted interventions engaging school-aged children to lead the delivery of community vector control and monitoring by training of teachers and enhancing school curriculum. ⁴⁸ The accrued public health evidence will facilitate scaling up of interventions that are capable of suppressing dengue infection across a multitude of cultural, geographic, and socio-economic dimensions.