An Integrated Intervention Model for the Prevention of Zika and Other Aedes-Borne Diseases in Women and their Families in Mexico

We describe and discuss the rationale, design and current implementation of a model for an integrated intervention for the primary and secondary prevention of Zika and other Aedes-borne diseases and sexually transmitted infections that impact reproductive health, pregnancy and perinatal life stages in women and their families in Merida, Mexico. The intervention includes enhanced surveillance of pregnant women, implementation of communication strategies to promote good practices to prevent disease transmission, determination of the frequency of structural anomalies detected prenatally in the foetus, umbilical cord and placenta of pregnancies diagnosed with ZIK infection, detection of ZIKV and other arboviruses/viruses in products of abortion, in-utero and early newborn, provision of Aedes aegypti-proof houses? (protecting homes with door/window screens with insecticide to prevent the access of mosquitoes), mosquito repellents, larvicides and education/promotion of best practices for the prevention of infection with dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) and an anthropological studies on sociocultural factors of pregnant women associated with ZIKV. This intervention is being developed in a population of 10,000 people of the city of Merida and with the participation of a multidisciplinary group of public health professionals in collaboration with the Ministry of Health and the Government of Yucatan

Insecticide-Treated House Screens to Reduce Infestations of Dengue Vectors

The public health importance of the endophilic mosquito Aedes aegypti increased dramatically in the recent decade, because it is the vector of dengue, chikungunya, Zika and yellow fever. The use of long-lasting insecticidal nets (LLINs) fixed on doors and windows, as insecticide-treated screening (ITS), is one innovative approach recently evaluated for Aedes control in South Mexico. From 2009 to 2014, cluster-randomised controlled trials were conducted in Acapulco and Merida. Intervention clusters received Aedes-proof houses (‘Casas a prueba de Aedes’) with ITS and were followed up during 2 years. Overall, results showed significant and sustained reductions on indoor adult vector densities in the treated clusters with ITS after 2 years: ca. 50% on the presence (OR ≤ 0.62, P < 0.05) and abundance (IRR ≤ 0.58, P < 0.05). ITS on doors and windows are ‘user-friendly’ tool, with high levels of acceptance, requiring little additional work or behavioural change by householders. Factors that favoured these interventions were (a) house construction, (b) high coverage achieved due to the excellent acceptance by the community and (c) collaboration of the vector control services; and only some operational complaints relating to screen fragility and the installation process. ITS is a housing improvement that should be part of the current paradigms for urban vector-borne disease control

Low-Cost Materials for Do-It-Yourself (DIY) Installation of House Screening against <em>Aedes aegypti</em>

House-screening (HS) using fixed-aluminium frames to reduce the risk of indoor infestation with Aedes aegypti mosquitoes as well as the risk of Aedes-transmitted diseases in communities living in endemic areas. However, the success of this approach has been hindered by the elevated cost of the aluminium-based materials as well as their professional installation, which cannot be afforded by people living under vulnerable conditions. Cost-saving strategies such as the use of low-cost materials including wood, PVC, and Velcro are within the list of HS options available and offered by HS businesses and/or Do-it-yourself (DIY) packages verbi gratia ready-made and ready-to-install mosquito-screens. Here, we evaluated the efficacy of low-cost frames constructed with different materials to protect against Ae. aegypti indoor infestation using experimental huts. The efficacy of protection in preventing female mosquito passing inside the huts of any of the options of frames was high (>93%) compared to the control with no-screen. People’s perceptions on the different materials showed the most “popular” alternative was the frame made of wood (62%). All the prototype-frames of HS made of different materials were effective at blocking Ae. aegypti entering-mosquitoes particularly, low-cost options like magnets and Velcro

Insecticide-treated house screening protects against Zika-infected Aedes aegypti in Merida, Mexico

There is strong and unquestionable epidemiological evidence of the protective efficacy of insecticide treated screens (ITS) against an arboviral disease of major relevance. Houses with ITS were 79-85% less infested with Aedes females than control houses during the peak of the zika epidemic, an effect that was significant up to a year. A similar significant trend was observed for blood-fed Ae. aegypti females (76-82%). Communities strongly accepted the intervention, due to its perceived mode of action, the prevalent risk for Aedes-borne diseases in the area, and the positive feedback from neighbours receiving ITS. The paper provides details of the study

Insecticide-treated house screening protects against Zika-infected Aedes aegypti in Merida, Mexico.

BackgroundThe integration of house-screening and long-lasting insecticidal nets, known as insecticide-treated screening (ITS), can provide simple, safe, and low-tech Aedes aegypti control. Cluster randomised controlled trials in two endemic localities for Ae. aegypti of south Mexico, showed that ITS conferred both, immediate and sustained (~2 yr) impact on indoor-female Ae. aegypti infestations. Such encouraging results require further validation with studies quantifying more epidemiologically-related endpoints, including arbovirus infection in Ae. aegypti. We evaluated the efficacy of protecting houses with ITS on Ae. aegypti infestation and arbovirus infection during a Zika outbreak in Merida, Yucatan, Mexico.Methodology/principal findingsA two-arm cluster-randomised controlled trial evaluated the entomological efficacy of ITS compared to the absence of ITS (with both arms able to receive routine arbovirus vector control) in the neighbourhood Juan Pablo II of Merida. Cross-sectional entomological surveys quantified indoor adult mosquito infestation and arbovirus infection at baseline (pre-ITS installation) and throughout two post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over one year (2016-2017). Household-surveys assessed the social reception of the intervention. Houses with ITS were 79-85% less infested with Aedes females than control houses up to one-year PI. A similar significant trend was observed for blood-fed Ae. aegypti females (76-82%). Houses with ITS had significantly less infected female Ae. aegypti than controls during the peak of the epidemic (OR = 0.15, 95%CI: 0.08-0.29), an effect that was significant up to a year PI (OR = 0.24, 0.15-0.39). Communities strongly accepted the intervention, due to its perceived mode of action, the prevalent risk for Aedes-borne diseases in the area, and the positive feedback from neighbours receiving ITS.Conclusions/significanceWe show evidence of the protective efficacy of ITS against an arboviral disease of major relevance, and discuss the relevance of our findings for intervention adoption

Community Engagement and Social Assessment for <em>Wolbachia</em>-Based Suppression of Natural Populations of <em>Aedes aegypti</em>: The Mexican Experience

The Wolbachia-based approach is under evaluation as a control strategy against Aedes aegypti in Mexico. From 2017 to 2019, we performed a pilot study to evaluate an open-field mass-release of wAlbB-infected Ae. aegypti male mosquitoes, as part of an integrated vector management (IVM) plan led by the Ministry of Health in Mexico to suppress natural populations of Ae. aegypti in southern Mexico. Community engagement and social evaluation were part of the key activities conducted. Overall, results showed the positive benefits of this Wolbachia-based method in the reduction of Aedes mosquitoes (90%). Mosquito’s nuisance at bedtime and the increasing circulation of mosquitoes during the releasing days were reported as the negative perceptions of this method. Importantly, participants understood the difference between wild mosquitoes and those released as part of the project, as well as the importance of the IVM. A significant number of the population accepted and supported the project, and feedback was given to improve future mosquito-releasing activities. The social license was a key factor in the success of the intervention and should be part of innovative paradigms for mosquito-vector control strategies involving community engagement. We outline the Mexican experience of community engagement and social assessment in implementing a Wolbachia-based strategy