Trial of a community-based intervention to decrease infestation of Aedes aegypti mosquitoes in cement washbasins in El Progreso, Honduras

Risk of dengue, Zika, and chikungunya transmission in the metropolitan area of Cucuta, Colombia: cross-sectional analysis, baseline for a cluster-randomised controlled trial of a novel vector tool for water containers

BACKGROUND

Arbovirus diseases such as dengue, Zika, and chikungunya are a public health threat in tropical and subtropical areas. In the absence of a vaccine or specific treatment, vector management (in this case the control of the primary vector Aedes aegypti) is the best practice to prevent the three diseases. A good understanding of vector behaviour, ecology, human mobility and water use can help design effective vector control programmes. This study collected baseline information on these factors for identifying the arbovirus transmission risk and assessed the requirements for a large intervention trial in Colombia.

METHODS

Baseline surveys were conducted in 5,997 households, randomly selected from 24 clusters (neighbourhoods with on average 2000 houses and 250 households inspected) in the metropolitan area of Cucuta, Colombia. The study established population characteristics including water management and mobility as well as larval-pupal indices which were estimated and compared in all clusters. Additionally, the study estimated disease incidence from two sources: self-reported dengue cases in the household survey and cases notified by the national surveillance system.

RESULTS

In all 24 study clusters similar social and demographic characteristics were found but the entomological indicators and estimated disease incidence rates varied. The entomological indicators showed a high vector infestation: House Index = 25.1%, Container Index = 12.3% and Breteau Index = 29.6. Pupae per person Index (PPI) as an indicator of the transmission risk showed a large range from 0.22 to 2.04 indicating a high transmission risk in most clusters. The concrete ground tanks for laundry -mostly outdoors and uncovered- were the containers with the highest production of Ae. aegypti as 86.3% of all 17,613 pupae were identified in these containers. Also, the annual incidence of dengue was high: 841.6 self-reported cases per 100,000 inhabitants and the dengue incidence notified by the National surveillance system was 1,013.4 cases per 100,000 in 2019. Only 2.2% of the households used container water for drinking. 40.3% of the study population travelled during the day (when Aedes mosquitoes bite) outside their clusters.

CONCLUSIONS

The production of Ae. aegypti mosquitoes occurred almost exclusively in concrete ground tanks for laundry (lavadero), the primary intervention target. The baseline study provides necessary evidence for the design and implementation of a cluster randomized intervention trial in Colombia.

Household ovicidal alternative for complementary control of Aedes aegypti in the Gran San Miguel de Tucuman agglomerate, Tucumán, Argentina

Aedes aegypti is closely related to human behavior that allows its establishment through the accumulation of urban solid waste where it lays resistant eggs. Generally, adulticides and larvicides are applied in excess, without ovicidal alternatives, and some household products can help reduce the abundance of quiescent eggs in breeding sites by affecting the viability of eggs. A community involved in prevention and control is one of the most effective strategies for adequate vector management. In this investigation, new alternative strategies for the control of Ae. aegypti are assessed, valuing in laboratory the eggs' response to diverse household products. Susceptibility to different doses of bleach, oil, salt, sodium bicarbonate, vinegar, coffee, garlic, peroxide, and alcohol was measured, as well as its duration over time. New home products were found as alternative ovicidal method. Bleach and sunflower oil had an ovicidal effect at their maximum doses and at almost all of the evaluation times. In contrast, vinegar and coffee had no ovicidal effect at any time, turning out to be stimulators of hatching in the laboratory. These alternative and complementary applications could optimize the surveillance and control of Ae. aegypti in the area, allowing new approaches to reduce populations by eliminating eggs on human microhabitats.

Proof of concept for eliminating Aedes aegypti production by means of integrated control including turtles, copepods, tilapia, larvicides, and community participation in Monte Verde, Honduras

Monte Verde, a peri‑urban squatter community near San Pedro Sula, virtually eliminated Aedes aegypti production in all known larval habitats: wells; water storage containers including pilas (open concrete water tanks used for laundry), 200-liter drums, 1000-liter plastic "cisterns," buckets; and objects collecting rainwater. The project began in 2016 when Monte Verde was overrun with dengue, Zika, and chikungunya. During more than a year of experimentation, Monte Verde residents crafted an effective, sustainable, and environmentally friendly toolkit that was inexpensive but required full community participation. Biological control with copepods, turtles, and tilapia was at the core of the toolkit, along with a mix of other methods such as getting rid of unnecessary containers, scrubbing them to remove Ae. aegypti eggs, and covering them to exclude mosquitoes or rainwater. Environmentally friendly larvicides also had a limited but crucial role. Key design features: (1) toolkit components known to be nearly 100% effective at preventing Ae. aegypti production when fitted to appropriate larval habitats; (2) using Ae. aegypti larval habitats as a resource by transforming them into "egg sinks" to drive Ae. aegypti population decline; (3) dedicated community volunteers who worked with their neighbors, targeting 100% coverage of all known Ae. aegypti larval habitats with an appropriate control method; (4) monthly monitoring in which the volunteers visited every house to assess progress and improve coverage as an ongoing learning experience for both volunteers and residents. Taking pupae as an indicator of Ae. aegypti production, from September 2018 to the end of the record in December 2021 (except for a brief lapse during COVID lockdown in 2020), the monthly count of pupae fluctuated between zero and 0.6% of the 22,984 pupae counted in the baseline survey at the beginning of the project. Adult Ae. aegypti declined to low numbers but did not disappear completely. There were no recognizable cases of dengue, Zika, or chikungunya after June 2018, though the study design based on a single site did not provide a basis for rigorous confirmation that Monte Verde's Ae. aegypti control program was responsible. Nonetheless, Monte Verde's success at eliminating Ae. aegypti production can serve as a model for extending this approach to other communities. Key ingredients for success were outside stimulation and facilitation to foster shared community awareness and commitment regarding the problem and its solution, enduring commitment of local leadership, compatibility of the toolkit with the local community, overcoming social obstacles, rapid results with "success breeding success," and building resilience.

Integrated disease management: arboviral infections and waterborne diarrhoea

Water-related diseases such as diarrhoeal diseases from viral, bacterial and parasitic organisms and Aedes-borne arboviral diseases are major global health problems. We believe that these two disease groups share common risk factors, namely inadequate household water management, poor sanitation and solid waste management. Where water provision is inadequate, water storage is essential. Aedes mosquitoes commonly breed in household water storage containers, which can hold water contaminated with enteric disease-causing organisms. Microbiological contamination of water between source and point-of-use is a major cause of reduced drinking-water quality. Inadequate sanitation and solid waste management increase not only risk of water contamination, but also the availability of mosquito larval habitats. In this article we discuss integrated interventions that interrupt mosquito breeding while also providing sanitary environments and clean water. Specific interventions include improving storage container design, placement and maintenance and scaling up access to piped water. Vector control can be integrated into sanitation projects that target sewers and drains to avoid accumulation of stagnant water. Better management of garbage and solid waste can reduce the availability of mosquito habitats while improving human living conditions. Our proposed integration of disease interventions is consistent with strategies promoted in several global health frameworks, such as the sustainable development goals, the global vector control response, behavioural change, and water, sanitation and hygiene initiatives. Future research should address how interventions targeting water, sanitation, hygiene and community waste disposal also benefit Aedes-borne disease control. The projected effects of climate change mean that integrated management and control strategies will become increasingly important.

A qualitative study of community perspectives surrounding cleaning practices in the context of Zika prevention in El Salvador: implications for community-based Aedes aegypti control

Background

In El Salvador, Aedes aegypti mosquitoes transmitting Zika and other arboviruses use water storage containers as important oviposition sites. Promotion of water storage container cleaning is a key element of prevention programs. We explored community perceptions surrounding cleaning practices among pregnant women, male partners of pregnant women, and women likely to become pregnant.

Methods

Researchers conducted 11 focus groups and 12 in-depth interviews which included individual elicitations of Zika prevention measures practiced in the community. Focus group participants rated 18 images depicting Zika-related behaviors according to effectiveness and feasibility in the community context, discussed influencing determinants, voted on community intentions to perform prevention behaviors, and performed washbasin cleaning simulations. In-depth interviews with male partners of pregnant women used projective techniques with images to explore their perceptions on a subset of Zika prevention behaviors.

Results

General cleaning of the home, to ensure a healthy environment, was a strong community norm. In this context, participants gave water storage container cleaning a high rating, for both its effectiveness and feasibility. Participants were convinced that they cleaned their water storage containers effectively against Zika, but their actual skills were inadequate to destroy Aedes aegypti eggs. A further constraint was the schedule of water availability. Even during pregnancy, male partners rarely cleaned water storage containers because water became available in homes when they were at work. Furthermore, prevailing gender norms did not foster male participation in domestic cleaning activities. Despite these factors, many men were willing to provide substantial support with cleaning when their partners were pregnant, in order to protect their family.

Conclusions

Behavior change programs for the prevention of Zika and other arboviruses need to improve community members’ mosquito egg destruction skills rather than perpetuate the promotion of non-specific cleaning in and around the home as effective. Egg elimination must be clearly identified as the objective of water storage container maintenance and programs should highlight the effective techniques to achieve this goal. In addition, programs must build the skills of family members who support pregnant women to maintain the frequency of effective egg destruction in all water storage containers of the home.

Community Perspectives on Zika Virus Disease Prevention in Guatemala: A Qualitative Study

Zika virus, which is transmitted by Aedes aegypti mosquitoes and through sexual transmission, disproportionally affects the human fetus. Guatemala experienced a surge of Zika cases beginning in 2016. We conducted a qualitative study of community perceptions of the seriousness of Zika, as well as the effectiveness, feasibility, and collective efficacy of Zika prevention actions. Free listing elicited the preventive actions salient for 68 participants comprising pregnant women, men with a pregnant partner, and women likely to become pregnant; 12 focus group discussions in a highland and a lowland town explored other concepts through rank orderings of prevention practices depicted on cards. Participants' initial concern about Zika, based on recent experience with chikungunya and high media coverage, diminished because of its mild symptoms and reduced media coverage. Participants identified more than 32 salient preventive actions, many of which are considered effective by programs. Participants ranked water storage container cleaning and regular unspecified cleaning of the house and its surroundings as highly effective, feasible, and of high collective efficacy; however, the actions lacked the specificity needed to effectively destroy mosquito eggs. Community-level removal of tires and discarded containers had lower collective efficacy than household-level implementation because of the municipal and community cooperation needed. Condom use, although salient for Zika prevention, was hindered by gender roles. The findings indicate space for increasing self-efficacy for condom use among fathers-to-be, abandoning nonspecific terms such as "cleaning" and "standing water," increasing people's skills in using bleach as an ovicide, and promoting antenatal care and family planning counseling.

Impact of a community-based intervention on Aedes aegypti and its spatial distribution in Ouagadougou, Burkina Faso

Background

Several studies highlighted the impact of community-based interventions whose purpose was to reduce the vectors’ breeding sites. These strategies are particularly interesting in low-and-middle-income countries which may find it difficult to sustainably assume the cost of insecticide-based interventions. In this case study we determine the spatial distribution of a community-based intervention for dengue vector control using different entomological indices. The objective was to evaluate locally where the intervention was most effective, using spatial analysis methods that are too often neglected in impact assessments.

Methods

Two neighbourhoods, Tampouy and Juvenat in Ouagadougou, Burkina Faso, were chosen among five after a survey was conducted, as part of an assessment related to the burden of dengue. As part of the community-based intervention conducted in Tampouy between August and early October 2016, an entomological survey was implemented in two phases. The first phase consisted of a baseline entomological characterization of potential breeding sites in the neighbourhood of Tampouy as well as in Juvenat, the control area. This phase was conducted in October 2015 at the end of the rainy season. The mosquito breeding sites were screened in randomly selected houses: 206 in Tampouy and 203 in Juvenat. A second phase took place after the intervention, in October 2016. The mosquito breeding sites were investigated in the same yards as during the baseline phase. We performed several entomological analyses to measure site productivity as well as before and after analysis using multilevel linear regression. We used Local Indicators of Spatial Association (LISAs) to analyse spatial concentrations of larvae.

Results

After the intervention, it is noted that LISAs at Tampouy reveal few aggregates of all types and the suppression of those existing before the intervention. The analysis therefore reveals that the intervention made it possible to reduce the number of concentration areas of high and low values of pupae.

Conclusions

The contribution of spatial methods for assessing community-based intervention are relevant for monitoring at local levels as a complement to epidemiological analyses conducted within neighbourhoods. They are useful, therefore, not only for assessment but also for establishing interventions. This study shows that spatial analyses also have their place in population health intervention research.

Social marketing interventions for the prevention and control of neglected tropical diseases: A systematic review

BACKGROUND

Social marketing is an approach to behavior change that contributes to disease prevention and control. This study aimed to understand how social marketing interventions have addressed neglected tropical diseases (NTDs). It examined the characteristics, breadth of coverage, and outcomes of social marketing interventions focused on the prevention and control of these diseases.

METHODOLOGY/PRINCIPAL FINDINGS

Studies published in any language between January 1971 and April 2017, targeting at least one of the 17 NTDs prioritized in the World Health Organization (WHO) NTD Roadmap were considered. Included studies had interventions that applied both, at least one core social marketing concept, "social behavioral influence", and one social marketing technique, "integrated intervention mix", described in the Hierarchical Model of Social Marketing. This review is registered with PROSPERO CRD42017063858. Twenty interventions, addressing eight NTDs, met the inclusion criteria. They focused on behaviors related to four of the five WHO public health strategies for NTDs. Most interventions incorporated the concepts "relationship building" and "public / people orientation focus", and the technique "insight-driven segmentation". All the interventions reported changing behavioral determinants such as knowledge, 19 reported behavior change, and four influenced health outcomes.

CONCLUSION/SIGNIFICANCE

Evidence from this study shows that social marketing has been successfully used to address behaviors related to most of the five public health strategic interventions for NTDs recommended by the WHO. It is suggested that social marketing interventions for the prevention and control of NTDs be grounded on an understanding of the audience and adapted to the contexts intervened. Building stakeholder relationships as early as possible, and involving the publics could help in reaching NTD outcomes. Elements of the intervention mix should be integrated and mutually supportive. Incorporating health education and capacity building, as well as being culturally appropriate, is also relevant. It is recommended that ongoing discussions to formulate the targets and milestones of the new global Roadmap for NTDs integrate social marketing as an approach to overcome these diseases.

The gender responsiveness of social marketing interventions focused on neglected tropical diseases

Background: Gender is a determinant of health that intersects with other social stratifiers to shape the health and well-being of populations. Despite the recognition of gender in the global health agenda, limited evidence exists about the integration of gender considerations in interventions, including social marketing interventions, for the prevention and control of neglected tropical diseases. Social marketing is an ethical approach to behavior change aiming to benefit individuals, communities, and society. Since behaviors are gendered and affect disease transmission and healthcare patterns, one would expect social marketing interventions to be gender responsive.Objective: This study aims to understand the extent to which social marketing interventions focusing on neglected tropical diseases are gender responsive.Methods: This study uses data from social marketing interventions collected in a systematic review, this study examined 20 interventions addressing eight neglected tropical diseases in 13 countries. A modified version of the World Health Organization Gender Assessment Tool (GAT) was used to determine the gender responsiveness of the interventions, which was complemented by coding for intersectional sex and gender data. These results are presented in 12 themes.Results: One schistosomiasis intervention implemented in China was assessed as gender responsive. It was not possible to answer many questions from the GAT due to limited data reported in the publications describing the interventions. Despite this, strengths and limitations were found in all the interventions in relation to the use of sex and gender concepts, the disaggregation of data, the consideration of environmental factors, and the involvement of women or men in the different stages of the interventions.Conclusions: Many interventions showed positive actions towards gender responsiveness. However, only one was classified as gender responsive. Others failed to supply enough data for assessment. Recommendations about how sex and gender could be integrated into social marketing interventions are provided.

Evidence-Based Process for Prioritizing Positive Behaviors for Promotion: Zika Prevention in Latin America and the Caribbean and Applicability to Future Health Emergency Responses

To maximize the impact of Zika prevention programming efforts, a prioritization process for social and behavior change programming was developed based on a combination of research evidence and programmatic experience. Prioritized behaviors were: application of mosquito repellent, use of condoms, removing unintentional standing water, covering and scrubbing walls of water storage containers, seeking prenatal care, and seeking counseling on family planning if not planning to get pregnant.

Since the 2015 Zika outbreak in Latin America and the Caribbean, a plethora of behavior change messages have been promoted to reduce Zika transmission. One year after the United States Agency for International Development (USAID) initiated its Zika response, more than 30 variants of preventive behaviors were being promoted. This situation challenged social and behavior change (SBC) programming efforts that require a coordinated response and agreed upon set of focus behaviors to be effective. To support USAID implementing partners in harmonizing prevention efforts to reduce Zika infection, we developed an evidence-based process to identify behaviors with the highest potential to reduce Zika infection and transmission. We compiled a full list of behaviors and selected the most promising for a full evidence review. The review included systematic keyword searches on Google Scholar, extraction of all relevant published articles on Aedes-borne diseases between 2012 and 2018, review of seminal papers, and review of gray literature. We examined articles to determine each behavior's potential effectiveness in preventing Zika transmission or reducing the Aedes aegypti population. We also developed assessment criteria to delineate the ease with which the target population could adopt each behavior, including: (1) required frequency; (2) feasibility of the behavior; and (3) accessibility and cost of the necessary materials in the setting. These behaviors were refined through a consensus-building process with USAID's Zika implementing partners, considering contextual factors. The resulting 7 evidence-based preventive behaviors have high potential to strengthen SBC programming's impact in USAID's Zika response: (1) apply mosquito repellent, (2) use condoms during pregnancy, (3) remove standing water, (4) cover water storage containers, (5) clean/remove mosquito eggs from water containers, (6) seek antenatal care, and (7) seek family planning counseling. This case study documents a flexible process that can be adapted to inform the prioritization of behaviors when there is limited evidence available, as during many emergency responses.

Assessment of combined tools and strategies for Aedes aegypti control with low environmental impact

The control of the mosquito vector Aedes aegypti L. (Diptera: Culicidae) is the main action against dengue, chikungunya, and Zika. The excessive use of conventional insecticides has promoted the development of other control methods and strategies with lower environmental impact. We evaluated the effectiveness of applying triflumuron 1 ppm and emptying water-filled containers in a field trial in temperate Argentina. Both control methods were implemented either individually or combined and regularly from the beginning of the mosquito reproductive season or once it reached peak abundance. The impact on a non-target midge of the genus Chironomus was also tested. The highest reductions of Ae. aegypti were achieved in treatments which included triflumuron. This effect was stronger when applied from the beginning of the reproductive season, with < 1.3% of positive containers throughout the entire season. No enhancing effects were obtained when combining both control methods. Treatments with triflumuron were not completely innocuous for the non-target species, with Chironomus sp. more susceptible to treatments including triflumuron applied from the beginning of the reproductive season than all others. Sharp reductions of mosquito populations in urban environments with high density of water-filled containers are possible with minimum container management efforts, by applying triflumuron 1 ppm every 6 weeks. In temperate urban settings, better results can be obtained when applications begin early in the reproductive season of the mosquito vector Aedes aegypti.

Comprehensive evaluation of male health in four communities in rural Honduras

PODEMOS (Partnership for Ongoing Developmental, Educational and Medical Outreach Solutions) has been a long-standing healthcare provider in 4 communities in northern rural Honduras. In this study, we sought to understand and quantify the health challenges faced by men in the rural communities served by PODEMOS in order to improve the way PODEMOS delivers healthcare. Between June and July of 2015, we conducted 104 structured survey interviews with men 18 years and older in rural Honduras. We found that most men face significant economic limitations in their ability to pay for healthcare and health-determining services and due to low formal education levels face health literacy challenges. Furthermore, we found that a quarter are at risk for health problems due to smoking, and the majority are at risk for musculoskeletal problems due to work in strenuous outdoor labor. However, we found that zero respondents drank alcohol heavily, which is defined as more than 14 drinks in one week. Lastly, we found varying opinions on female contraception use. Our findings indicate that medical brigades to the developing world should understand and quantify the relevant health challenges faced by their target populations.

"We need people to collaborate together against this disease": A qualitative exploration of perceptions of dengue fever control in caregivers' of children under 5 years, in the Peruvian Amazon

Background

Dengue Fever presents a significant and growing burden of disease to endemic countries, where children are at particular risk. Worldwide, no effective anti-viral treatment has been identified, thus vector control is key for disease prevention, particularly in Peru where no vaccine is currently available. This qualitative study aimed to explore the perceptions of dengue control in caregivers’ of children under 5 years in Peru, to help direct future mosquito control programmes and strategy.

Methods

Eighteen semi-structured interviews were conducted in one health centre in Iquitos, Peru. Interviews were audio-recorded, transcribed and translated by an independent translator. Data were analysed using an inductive thematic approach.

Findings

Three core analytic themes were interpreted: (1) awareness of dengue and its control, (2) perceived susceptibility of children, rural riverside communities and city inhabitants, and (3) perceived responsibility of vector control. Participants were aware of dengue symptoms, transmission and larvae eradication strategies. Misconceptions about the day-time biting behaviour of the Aedes aegypti mosquito and confusion with other mosquito-borne diseases influenced preventative practice. Community-wide lack of cooperation was recognised as a key barrier. This was strengthened by attitudes that the government or health centre were responsible for dengue control and a belief that the disease cannot be prevented through individual actions. Participants felt powerless to prevent dengue due to assumed inevitability of infection and lack of faith in preventative practices. However, children and rural communities were believed to be most vulnerable.

Conclusions

Perceptions of dengue control amongst caregivers to under 5’s were important in shaping their likelihood to participate in preventative practices. There is a need to address the perceived lack of community cooperation through strategies creating a sense of ownership of community control and enhancing social responsibility. The belief that dengue cannot be prevented by individual actions in a community also warrants attention. Specific misconceptions about dengue should be addressed through the community health worker system and further research directed to identify the needs of certain vulnerable groups.

Dengue fever is the most rapidly spreading mosquito-borne viral disease in the world and is a significant international health problem. It is endemic in the Peruvian Amazon and since there is no available vaccine or effective treatment, mosquito control is key. This novel study used qualitative interviews to explore the perceptions and experiences of dengue control in caregivers’ to children under 5 years, to help inform future Peruvian mosquito control programmes. Findings suggested that caregivers had basic knowledge about dengue, but that misconceptions around the mosquito itself and confusion with other diseases (like malaria) influenced people’s protective practice. Furthermore, participants felt powerless to prevent dengue since the invisible mosquito, perceived ineffective prevention methods, and rural riverside environment made the disease seem inevitable. Despite this, children and rural riverside communities were identified as most vulnerable groups. Key findings suggested a lack of community cooperation in mosquito prevention due to an attitude that the government and health centre were responsible for disease control, and the belief that dengue cannot be prevented through individual actions alone. These were important barriers to community mosquito prevention efforts. The findings from this study provide novel insights into how perceptions of dengue control can impact prevention in an endemic country.

A cross-sectional survey of Aedes aegypti immature abundance in urban and rural household containers in central Colombia

Background

Aedes aegypti, the major vector of dengue, breeds in domestic water containers. The development of immature mosquitoes in such containers is influenced by various environmental, ecological and socioeconomic factors. Urban and rural disparities in water storage practices and water source supply may affect mosquito immature abundance and, potentially, dengue risk. We evaluated the effect of water and container characteristics on A. aegypti immature abundance in urban and rural areas. Data were collected in the wet season of 2011 in central Colombia from 36 urban and 35 rural containers, which were either mosquito-positive or negative. Immature mosquitoes were identified to species. Data on water and container characteristics were collected from all containers.

Results

A total of 1452 Aedes pupae and larvae were collected of which 81% were A. aegypti and 19% A. fluviatilis. Aedes aegypti immatures were found in both urban and rural sites. However, the mean number of A. aegypti pupae was five times higher in containers in the urban sites compared to those in the rural sites. One of the important factors associated with A. aegypti infestation was frequency of container washing. Monthly-washed or never-washed containers were both about four times more likely to be infested than those washed every week. There were no significant differences between urban and rural sites in frequency of washing containers. Aedes aegypti immature infestation was positively associated with total dissolved solids, but negatively associated with dissolved oxygen. Water temperature, total dissolved solids, ammonia, nitrate, and organic matter were significantly higher in urban than in rural containers, which might explain urban-rural differences in breeding of A. aegypti. However, many of these factors vary substantially between studies and in their degree of association with vector breeding, therefore they may not be reliable indices for vector control interventions.

Conclusions

Although containers in urban areas were more likely to be infested with A. aegypti, rural containers still provide suitable habitats for A. aegypti. Containers that are washed more frequent are less likely to produce A. aegypti. These results highlight the importance of container washing as an effective vector control tool in both urban and rural areas. In addition, alternative designs of the highly productive washbasins should continue to be explored. To control diseases such as dengue, Zika and chikungunya, effective vector breeding site control must be implemented in addition to other interventions.

Impact of health education based intervention on community's awareness of dengue and its prevention in Delhi, India

Dengue is endemic in India. The capital, Delhi, continues to witness a higher number of cases due to urbanization-related factors. This study is intended to implement health education towards prevention of dengue, and to assess its impact on people's knowledge and practices related to causes and prevention of dengue among urban poor in Delhi. Pre- ( n = 484) and post- ( n = 496) intervention surveys from 15 sub-clusters from five slums/slum-like settlements in Delhi were carried out. Health education based intervention was carried out through partnership with the municipal bodies and non-governmental organizations. Socio-demographic characteristics of participants were similar in both surveys. Intervention resulted in significant increase in knowledge on cause, symptom perception and mosquito behaviour in terms of breeding and biting habits. Practice of personal protection measures increased significantly. The participation of people increased during intervention compared to the routine programme. Health education based interventions are instrumental in improving people's knowledge and behaviour. Hence, routine health educational activities as a supportive strategy in the health system need to be strengthened. New integrated approaches such as eco-bio-social approaches with community participation are to be developed and tested in endemic settings like Delhi.

Efficacy, Safety and Cost of Insecticide Treated Wall Lining, Insecticide Treated Bed Nets and Indoor Wall Wash with Lime for Visceral Leishmaniasis Vector Control in the Indian Sub-continent: A Multi-country Cluster Randomized Controlled Trial

BACKGROUND

We investigated the efficacy, safety and cost of lime wash of household walls plus treatment of sand fly breeding places with bleach (i.e. environmental management or EM), insecticide impregnated durable wall lining (DWL), and bed net impregnation with slow release insecticide (ITN) for sand fly control in the Indian sub-continent.

METHODS

This multi-country cluster randomized controlled trial had 24 clusters in each three sites with eight clusters per high, medium or low sand fly density stratum. Every cluster included 45-50 households. Five households from each cluster were randomly selected for entomological measurements including sand fly density and mortality at one, three, nine and twelve months post intervention. Household interviews were conducted for socioeconomic information and intervention acceptability assessment. Cost for each intervention was calculated. There was a control group without intervention.

FINDINGS

Sand fly mortality [mean and 95%CI] ranged from 84% (81%-87%) at one month to 74% (71%-78%) at 12 months for DWL, 75% (71%-79%) at one month to 49% (43%-55%) at twelve months for ITN, and 44% (34%-53%) at one month to 22% (14%-29%) at twelve months for EM. Adjusted intervention effect on sand fly density measured by incidence rate ratio ranged from 0.28 (0.23-0.34) at one month to 0.62 (0.51-0.75) at 12 months for DWL; 0.72 (0.62-0.85) at one month to 1.02 (0.86-1.22) at 12 months for ITN; and 0.89 (0.76-1.03) at one months to 1.49 (1.26-1.74) at 12 months for EM. Household acceptance of EM was 74% compared to 94% for both DWL and ITN. Operational cost per household in USD was about 5, 8, and 2 for EM, DWL and ITN, respectively. Minimal adverse reactions were reported for EM and ITN while 36% of households with DWL reported transient itching.

INTERPRETATION

DWL is the most effective, durable and acceptable control method followed by ITN. The Visceral Leishmaniasis (VL) Elimination Program in the Indian sub-continent should consider DWL and ITN for sand fly control in addition to IRS.

Meta-analysis of studies on chemical, physical and biological agents in the control of Aedes aegypti

Background

Aedes aegypti is a vector of international concern because it can transmit to humans three important arboviral diseases: yellow fever, dengue and chikungunya. Epidemics that are repeated year after year in a variety of urban centers indicate that there are control failures, allowing the vector to continue expanding.

Methods

To identify the most effective vector control strategies and the factors that contributed to the success or failure of each strategy, we carried out a systematic review with meta-analysis of articles published in 12 databases, from 1974 to the month of December 2013. We evaluated the association between the use of whatever chemical substance, mechanical agent, biological or integrated actions against A. aegypti and the control of the vector, as measured by 10 indicators.

Results

We found 2,791 articles, but after careful selection, only 26 studies remained for analysis related to control interventions implemented in 15 countries, with 5 biological, 5 chemical, 3 mechanical and 13 integrated strategies. The comparison among all of them, indicated that the control of A. aegypti is significantly associated with the type of strategy used, and that integrated interventions consist of the most effective method for controlling A. aegypti.

Conclusions

The most effective control method was the integrated approach, considering the influence of eco-bio-social determinants in the virus-vector-man epidemiological chain, and community involvement, starting with community empowerment as active agents of vector control.

Evaluation of Household Bleach as an Ovicide for the Control of Aedes aegypti

Accumulations of dormant eggs in container habitats allow Aedes aegypti populations to survive harsh environmental conditions and may frustrate control interventions directed at larval and adult life stages. While sodium hypochlorite solutions (NaOCl) have long been recognized as ovicides for use against dengue vectors, the susceptibility of eggs to spray applications has not been robustly evaluated on substrate materials representative of the most frequently utilized artificial container habitats. Experiments were performed under controlled and natural conditions by applying dilutions of household bleach (52.5 ppt NaOCl) as a spray to eggs on plastic, rubber, and concrete surfaces, with and without a smectite clay thickener. Laboratory assays identified the minimum NaOCl concentrations required to eliminate eggs on plastic (10 ppt), rubber (20 ppt) and concrete (20 ppt) surfaces. Addition of smectite clay reduced the minimum effective concentration to 10 ppt NaOCl for all 3 substrates. A minimum exposure period of 24 h was required to completely eliminate egg viability on concrete surfaces, even at the highest NaOCl concentration (52.5 ppt). Field experiments verified that spray application of a 1∶3 dilution of household bleach mixed with smectite clay can reduce egg hatching by ≥ 99% in shaded and sun-exposed plastic containers. Similarly, 4∶1 dilution of household bleach (with or without smectite clay) eliminated ≥ 98% of eggs from concrete surfaces in outdoor, water-filled drums. In this study, we propose a practical, effective and safe strategy for using household bleach to eliminate Ae. aegypti eggs in a range of artificial container habitats.

Control of the Asian tiger mosquito (Aedes albopictus) in a firmly established area in Spain: risk factors and people's involvement

BACKGROUND

The tiger mosquito is a competent vector of dengue and chikungunya in Europe. Therefore, evaluating control strategies is a priority. In this work we aimed to determine the key factors affecting Aedes albopictus production, the preferred larval habitats, and we explored the involvement of the citizens in Sant Cugat, Spain.

METHODS

A source-reduction campaign including door-to-door visits and interviews to local inhabitants (2008-2010) and larval surveys (2010) was carried out.

RESULTS

Civil workers inspected 3720 premises and interviewed 820 local inhabitants. Larval habitats, detected in 7.2% of the premises (n=266), were negatively associated with primary residence OR=0.4 (95% CI 0.3-0.6); and positively associated with schools OR=2.4 (95% CI 1.1-5.0), solid waste OR=5.1 (95% CI 3.0-8.9), scuppers OR=5.0 (95% CI 3.5-7.3) among other variables. Preventive measures were taken by 83.2% of householders (n=682). In 2010, 10.3% more citizens claimed to avoid having stagnant water compared with 2008. Simultaneously another 10.3% stopped using insecticides.

CONCLUSION

Solid waste, scuppers and vegetable gardens were found to be important factors characterizing premises with larval habitats. People claimed to know about this insect and they considered it to be an important issue that diminished their quality of life.

Mediational effects of self-efficacy dimensions in the relationship between knowledge of dengue and dengue preventive behaviour with respect to control of dengue outbreaks: a structural equation model of a cross-sectional survey

BACKGROUND

Dengue fever is endemic in Malaysia, with frequent major outbreaks in urban areas. The major control strategy relies on health promotional campaigns aimed at encouraging people to reduce mosquito breeding sites close to people's homes. However, such campaigns have not always been 100% effective. The concept of self-efficacy is an area of increasing research interest in understanding how health promotion can be most effective. This paper reports on a study of the impact of self-efficacy on dengue knowledge and dengue preventive behaviour.

METHODS AND FINDINGS

We recruited 280 adults from 27 post-outbreak villages in the state of Terengganu, east coast of Malaysia. Measures of health promotion and educational intervention activities and types of communication during outbreak, level of dengue knowledge, level and strength of self-efficacy and dengue preventive behaviour were obtained via face-to-face interviews and questionnaires. A structural equation model was tested and fitted the data well (χ(2) = 71.659, df = 40, p = 0.002, RMSEA = 0.053, CFI = 0.973, TLI = 0.963). Mass media, local contact and direct information-giving sessions significantly predicted level of knowledge of dengue. Level and strength of self-efficacy fully mediated the relationship between knowledge of dengue and dengue preventive behaviours. Strength of self-efficacy acted as partial mediator in the relationship between knowledge of dengue and dengue preventive behaviours.

CONCLUSIONS

To control and prevent dengue outbreaks by behavioural measures, health promotion and educational interventions during outbreaks should now focus on those approaches that are most likely to increase the level and strength of self-efficacy.

Regulation of Aedes aegypti population dynamics in field systems: quantifying direct and delayed density dependence

Transgenic strains of Aedes aegypti have been engineered to help control transmission of dengue virus. Although resources have been invested in developing the strains, we lack data on the ecology of mosquitoes that could impact the success of this approach. Although studies of intra-specific competition have been conducted using Ae. aegypti larvae, none of these studies examine mixed age cohorts at densities that occur in the field, with natural nutrient levels. Experiments were conducted in Mexico to determine the impact of direct and delayed density dependence on Ae. aegypti populations. Natural water, food, and larval densities were used to estimate the impacts of density dependence on larval survival, development, and adult body size. Direct and delayed density-dependent factors had a significant impact on larval survival, larval development, and adult body size. These results indicate that control methods attempting to reduce mosquito populations may be counteracted by density-dependent population regulation.

Trials of improved practices (TIPs): a strategy for making long-lasting nets last longer?

Long-lasting insecticidal net (LLIN) use is a proven malaria prevention method. Mass distribution has greatly expanded LLIN access in sub-Saharan Africa, but a gap remains between LLIN ownership and use. Furthermore, LLINs wear out more quickly than anticipated. This paper suggests a participatory research strategy-trials of improved practices (TIPs)-that could identify locally appropriate approaches to prolonging net life and increasing effective use. We used TIPs to overcome barriers to optimal net use in the Peruvian Amazon. Working with 15 families in three villages, we tested home treatment of cotton nets, use of an alternative netting fabric, and alternative washing and care instructions. TIPs helped confirm feasibility of these interventions. Although our findings are time- and context-specific, TIPs could help improve consistency and effectiveness of current LLIN use and prolong net lifespan in sub-Saharan Africa and elsewhere. This would help maximize the value of shrinking donor resources for malaria.

Assessing the impact of density dependence in field populations of Aedes aegypti

Although many laboratory studies of intra-specific competition have been conducted with Ae. aegypti, there have been few studies in natural environments and none that examined density dependence in natural containers at normal field densities. Additionally, current mathematical models that predict Ae. aegypti population dynamics lack empirically-based functions for density-dependence. We performed field experiments in Tapachula, Mexico, where dengue is a significant public health concern. Twenty-one containers with natural food and water that already contained larvae were collected from local houses. Each container was divided in half and the naturally occurring larvae were apportioned in a manner that resulted in one side of the container (high density) having four times the density of the second side (low density). Larvae were counted and pupae were removed daily. Once adults emerged, wing span was measured to estimate body size. Density had a significant impact on larval survival, adult body size, and the time taken to transition from 4(th) instar to pupation. Increased density decreased larval survival by 20% and decreased wing length by an average of 0.19 mm. These results provide a starting point for a better understanding of density dependence in field populations of Ae. aegypti.

Dengue vector control strategies in an urban setting: an economic modelling assessment

BACKGROUND

An estimated 2·5 billion people are at risk of dengue. Incidence of dengue is especially high in resource-constrained countries, where control relies mainly on insecticides targeted at larval or adult mosquitoes. We did epidemiological and economic assessments of different vector control strategies.

METHODS

We developed a dynamic model of dengue transmission that assesses the evolution of insecticide resistance and immunity in the human population, thus allowing for long-term evolutionary and immunological effects of decreased dengue transmission. We measured the dengue health burden in terms of disability-adjusted life-years (DALYs) lost. We did a cost-effectiveness analysis of 43 insecticide-based vector control strategies, including strategies targeted at adult and larval stages, at varying efficacies (high-efficacy [90% mortality], medium-efficacy [60% mortality], and low-efficacy [30% mortality]) and yearly application frequencies (one to six applications). To assess the effect of parameter uncertainty on the results, we did a probabilistic sensitivity analysis and a threshold analysis.

FINDINGS

All interventions caused the emergence of insecticide resistance, which, with the loss of herd immunity, will increase the magnitude of future dengue epidemics. In our model, one or more applications of high-efficacy larval control reduced dengue burden for up to 2 years, whereas three or more applications of adult vector control reduced dengue burden for up to 4 years. The incremental cost-effectiveness ratios of the strategies for two high-efficacy adult vector control applications per year was US$615 per DALY saved and for six high-efficacy adult vector control applications per year was $1267 per DALY saved. Sensitivity analysis showed that if the cost of adult control was more than 8·2 times the cost of larval control then all strategies based on adult control became dominated.

INTERPRETATION

Six high-efficacy adult vector control applications per year has a cost-effectiveness ratio that will probably meet WHO's standard for a cost-effective or very cost-effective intervention. Year-round larval control can be counterproductive, exacerbating epidemics in later years because of evolution of insecticide resistance and loss of herd immunity. We suggest the reassessment of vector control policies that are based on larval control only.

FUNDING

The Fulbright Programme, CAPES (Brazilian federal agency for post-graduate education), the Miriam Burnett trust, and the Notsew Orm Sands Foundation.

An ecosystemic approach to evaluating ecological, socioeconomic and group dynamics affecting the prevalence of Aedes aegypti in two Colombian towns

This article focuses on the epidemiological methods and results of a global Ecohealth study that explored the complexity of the relationship between ecological, biological, economical, social and political factors and vector presence. The study was carried out in two dengue endemic areas of Colombia. A transdisciplinary team gathered quantitative and qualitative data. A survey in randomly sampled households was applied and, simultaneously, direct observation of potential breeding sites was carried out. Logistic regressions and qualitative techniques were used. Qualitative and quantitative data were compared using triangulation. The presence of low water containers increases seven-fold the risk of finding immature forms of Aedes aegypti in the household (OR = 7.5; 95%CI: 1.7-32.2). An inverse association between socioeconomic stratum and presence of the vector was identified (Low stratum OR = 0.9; 95%CI: 0.6-1.4; High stratum OR =0.4; 95%CI: 0.07-1.7). Water management is a complex social dynamic associated with the presence of Ae. aegypti. Dengue control is a challenge for public health authorities and researchers as they should address promotion and prevention strategies that take into account cultural, behavioral, socioeconomic and health factors.

Effect of dengue vector control interventions on entomological parameters in developing countries: a systematic review and meta-analysis

The aim of this review was to compare the effects of different dengue vector control interventions (i.e. biological control, chemical control, environmental management and integrated vector management) with respect to the following entomological parameters: Breteau index (BI), container index (CI), and house index (HI). We systematically searched PubMed, ISI Web of Science, Science Direct, the Dengue Bulletin of the World Health Organization and reference lists of retrieved articles on dengue vector control interventions in developing countries. We extracted data on the effectiveness of different dengue vector control interventions (defined as the relative reduction of an entomological measure caused by the intervention compared with the control or pre-intervention phase) and calculated a measure of combined relative effectiveness, with 95% confidence intervals (95% c.i.). We identified 56 publications covering 61 dengue vector control interventions. Integrated vector management was found to be the most effective method to reduce the CI, HI and BI, resulting in random combined relative effectiveness values of 0.12 (95% c.i. 0.02-0.62), 0.17 (95% c.i. 0.02-1.28) and 0.33 (95% c.i. 0.22-0.48), respectively. Environmental management showed a relatively low effectiveness of 0.71 (95% c.i. 0.55-0.90) for the BI, 0.49 (95% c.i. 0.30-0.79) for the CI and 0.43 (95% c.i. 0.31-0.59) for the HI. Biological control (relative effectiveness for the CI: 0.18) usually targeted a small number of people (median population size: 200; range 20-2500), whereas integrated vector management focused on larger populations (median: 12 450; range: 210-9 600 000). In conclusion, dengue vector control is effective in reducing vector populations, particularly when interventions use a community-based, integrated approach, which is tailored to local eco-epidemiological and sociocultural settings and combined with educational programmes to increase knowledge and understanding of best practice. New research should assess the density-dependent effectiveness of each control measure in order to estimate whether reducing vector numbers has an impact on dengue transmission when populations are at a critical threshold.

Community and school-based health education for dengue control in rural Cambodia: a process evaluation

Dengue fever continues to be a major public health problem in Cambodia, with significant impact on children. Health education is a major means for prevention and control of the National Dengue Control Program (NDCP), and is delivered to communities and in schools. Drawing on data collected in 2003–2004 as part of an ethnographic study conducted in eastern Cambodia, we explore the approaches used in health education and their effectiveness to control dengue. Community health education is provided through health centre outreach activities and campaigns of the NDCP, but is not systematically evaluated, is under-funded and delivered irregularly; school-based education is restricted in terms of time and lacks follow-up in terms of practical activities for prevention and control. As a result, adherence is partial. We suggest the need for sustained routine education for dengue prevention and control, and the need for approaches to ensure the translation of knowledge into practice.

Health education is essential for the control of diseases such as dengue, ensuring that community members understand the mechanisms of infection and the key behaviours or activities that need to be addressed to prevent transmission, reduce severe disease and avoid fatalities. In Cambodia, health education for dengue control is provided in primary schools, at village health centres and by the National Dengue Control Program. However, these educational programs are accorded low priority, strategies and materials are not evaluated on a routine basis, messages are sometimes confusing, and health staff and teachers lack the training, time and opportunities to deliver educational messages. Recommendations to villages are not always practical or effective in preventing mosquito bites, and funds are not available to provide new educational materials. While school children and their parents therefore have some familiarity with the behaviour and habitat of the aedes mosquito and the environmental factors that contribute to dengue fever, their knowledge is uneven and knowledge is rarely translated to reduce the risk of infection. Community involvement in the prevention and control of dengue is essential, but will not be effective while health education is poorly resourced and irregular and lessons on prevention do not result in action.

Health seeking and access to care for children with suspected dengue in Cambodia: an ethnographic study

BACKGROUND

The continuing contribution of dengue fever to the hospitalization and deaths in hospital of infants and small children in Cambodia is associated with delays in presentation for medical attention, diagnosis and appropriate care. It is important to identify the reasons that influence these delays, in order to develop appropriate interventions to redress the impact of dengue.

METHODS

Data on health seeking were collected during an ethnographic study conducted in two villages in the eastern province of Kampong Cham, Cambodia in 2004. Interviews were conducted with mothers whose children had been infected with suspected dengue fever, or who had been sick for other reasons, in 2003 and 2004.

RESULTS

Women selected a therapeutic option based on perceptions of the severity of the child's condition, confidence in the particular modality, service or practitioner, and affordability of the therapy. While they knew what type of health care was required, poverty in combination with limited availability and perceptions of the poor quality of care at village health centers and public referral hospitals deterred them from doing so. Women initially used home remedies, then sought advice from public and private providers, shifting from one sector to another in a pragmatic response to the child's illness.

CONCLUSION

The lack of availability of financial resources for poor people and their continuing lack of confidence in the care provided by government centres combine to delay help seeking and inappropriate treatment of children sick with dengue.

What do community-based dengue control programmes achieve? A systematic review of published evaluations

Owing to increased epidemic activity and difficulties in controlling the insect vector, dengue has become a major public health problem in many parts of the tropics. The objective of this review is to analyse evidence regarding the achievements of community-based dengue control programmes. Medline, EMBASE, WHOLIS and the Cochrane Database of Systematic Reviews were searched (all to March 2005) to identify potentially relevant articles using keywords such as 'Aedes', 'dengue', 'breeding habits', 'housing' and 'community intervention'. According to the evaluation criteria recommended by the Cochrane Effective Practice and Organisation of Care Review Group, only studies that met the inclusion criteria of randomised controlled trials (RCT), controlled clinical trials (CCT), controlled before and after trials (CBA) or interrupted time series (ITS) were included. Eleven of 1091 studies met the inclusion criteria. Of these, two were RCTs, six were CBAs and three were ITS. The selected studies varied widely with respect to target groups, intervention procedures and outcome measurements. Six studies combined community participation programmes with dengue control tools. Methodological weaknesses were found in all studies: only two papers reported confidence intervals (95% CI); five studies reported P-values; two studies recognised the importance of water container productivity as a measure for vector density; in no study was cluster randomisation attempted; and in no study were costs and sustainability assessed. Evidence that community-based dengue control programmes alone and in combination with other control activities can enhance the effectiveness of dengue control programmes is weak.

Folk knowledge about dengue mosquitoes and contributions of health belief model in dengue control promotion in Northeast Thailand

The health belief model (HBM) has been adopted as the principal theory for health education and communication for dengue haemorrhagic fever (DHF) prevention and control in Thailand. The HBM focuses on persuading people to acknowledge their vulnerability and susceptibility to DHF, and the benefits of undertaking dengue larval control in household water containers. This study was undertaken in Khon Kaen province to investigate folk knowledge and beliefs about dengue mosquitoes and larval control campaigns and relating these to the theoretical components of HBM. Findings from this study indicate that health education messages can raise awareness during an outbreak but do not ensure sustained larval control practices. Several barriers are identified, including insufficient control agents, inadequate knowledge of control methods, and incompatibility of control practices with people's beliefs. The barriers prevail over the benefits of recommended larval control practices. In developing health education messages, consideration should go beyond the HBM and focus on control methods that are compatible with the socio-cultural environment in which control practices are being encouraged.

Intersectoral coordination in Aedes aegypti control. A pilot project in Havana City, Cuba

Background The 55th World Health Assembly declared dengue prevention and control a priority and urged Member States to develop sustainable intersectoral strategies to this end. To provide evidence for the reorientation of the dengue prevention policy in Cuba, we launched an intervention study to document the effectiveness of a local-level intersectoral approach.

METHODS

We used a quasi-experimental design. Social scientists introduced participatory methods to facilitate dialogue in the biweekly meetings of the intersectoral Health Council of the intervention area. This council subsequently developed an intersectoral plan for dengue prevention, of which the core objective was to design and implement activities for communication and social mobilization. In the control area, routine dengue control activities continued without additional input. Knowledge, attitudes and perceptions of dengue, and entomological indices were compared inside and between the areas before and after the 1-year intervention period.

RESULTS

In the intervention area the Health Council elaborated an intersectoral plan for dengue prevention focused on source reduction. The Aedes aegypti control methods consisted in eliminating useless containers in the houses and surroundings, covering tanks, and cleaning public and inhabited areas. It was implemented through communication and social mobilization. The Health Council in the control area occasionally discussed dengue issues but did not develop a coordinated action plan. Good knowledge about breeding sites and disease symptoms increased significantly (by 49.7% and 17.1% respectively) in the intervention area as well as the proportion of respondents eliminating containers in and around their houses (by 44%). No changes were observed in the control area. The House Index in the intervention area was 3.72% at baseline and decreased to 0.61% after 1 year. In the control area it remained stable throughout the study period (1.31% and 1.65% respectively).

CONCLUSION

The introduction of a participatory approach by social scientists promotes changes in intersectoral management. This facilitates social mobilization which, in its turn, leads to significant changes in knowledge, attitudes and dengue-related practices in the population and eventually to more effective control of Ae. aegypti.