Casas a prueba de Aedes aegypti para maximizar el control y la prevencion del dengue y chikungunya en Yucatán

Las mallas impregnadas con insecticida de larga duración (MILDs) son un método innovador y prometedor, en particular para el control sostenido de las hembras de Ae. aegypti en el interior de las viviendas, así como la reducción de contacto vector-humano. En este estudio se evaluó la intervención “casas a prueba de Ae. aegypti", que consistió en la instalación MILDs colocadas como mosquiteras fijas en puertas y ventanas en casas de una colonia de Mérida Yucatán con un total de 5 conglomerados tratamiento y 5 control (100 casas/cluster). Se llevaron colectas entomológicas para cuantificar la presencia y la prevalencia de mosquitos adultos en el interior de los domicilios a intervalos de 6 meses, correspondientes a las temporadas de secas/lluvias durante un año (2016 - 2017). En total, 500 hogares recibieron la intervención (100% de la cobertura), los cuales mostraron reducciones significativas en la presencia y abundancia de Ae. aegypti en el interior de la vivienda. Así mismo, se realizaron bioensayos de prueba de túnel para evaluar el comportamiento de las hembras de Ae. aegypti (cepas susceptibles y resistentes a piretroides) contra una MILD con diferentes tiempos de "edad" (malla nueva, expuesta en el campo después de 6 meses y 1 año) y diferentes tipos de daños (sin daños, daños centrales, daños laterales y nueve huecos). Todos los daños y tiempos requirieron de 40 hembras de mosquitos durante 40 minutos en el dispositivo del túnel. Las mallas demostraron un 100% de efectividad bloqueando el paso de los mosquitos cuando no presentaban daños, el tipo de daño es el principal factor que afecto el bloqueo y la alimentación sanguínea, aumentando en 1.5 cuando hay daño de nueve huecos y 1.9 cuando hay daño central, en comparación con el daño lateral. La edad y el tipo de daño afectaron de manera significativa el derribo y la mortalidad en ambas cepas, el derribo y la mortalidad registraron un 44% en la cepa resistente y 84% en la cepa susceptible cuando las mallas no presentaban daño. La aceptación del proceso intervención fue de un 91.43% por parte de los pobladores y el 100% califico la intervención como eficaz, de los cuales el 58% manifestó la total ausencia de mosquitos en el interior de su vivienda. Abstract Long-lasting insecticide impregnated nets are an innovative and promising method, particularly for the sustained control of Aedes aegypti females in the interior of the premises as well as the reduction of vector-human contact. In this study, the intervention "casas a prueba de Aedes aegypti", which consisted in the installation of LLINs fixed on doors and windows in houses of a colony of Merida Yucatan with a total of 5 conglomerates of treatment and 5 control (100 houses / cluster). Quantify the presence and prevalence of adult mosquitoes inside homes at 6-month intervals, corresponding to the dry / rainy seasons during one year (2016 - 2017). A total of 500 households received the intervention (100% of coverage) the same significant reductions in the presence and abundance of Aedes aegypti in the interior of the house. As well as tunnel test bioassays to evaluate the behavior of the Aedes aegypti females (susceptible strains and resistant strain to pyrethroids) against a LLINs with different aging nets times (new net, 6 months’ net, 12 months’ net), and types of damage (Non-damage, central damage, lateral damage and 9 holes). All damages and times required of 40 female mosquitoes during 40 minutes in the tunnel device. The nets showed 100% of blocking the passage of mosquitoes when no damage occurs, the type of damage is the main factor affecting the blockage and bloodfeding, the increase of 1.5 when there is damage of nine holes and 1.9 when there is Central damage, compared to the lateral damage. Age and type of damage affected significantly knock down and mortality in both strains, knock down and mortality registered 44% in the resistant strain and 84% in the susceptible strain when the nets showed no damage. The acceptance of the intervention process was 91.43% on the part of the inhabitants and 100% of the intervention as effective, of which 58% manifests the total absence of mosquitoes inside their home

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

House screening with insecticide-treated netting provides sustained reductions in domestic populations of Aedes aegypti in Merida, Mexico.

There is a need for effective methods to control Aedes aegypti and prevent the transmission of dengue, chikungunya, yellow fever and Zika viruses. Insecticide treated screening (ITS) is a promising approach, particularly as it targets adult mosquitoes to reduce human-mosquito contact. A cluster-randomised controlled trial evaluated the entomological efficacy of ITS based intervention, which consisted of the installation of pyrethroid-impregnated long-lasting insecticide-treated netting material fixed as framed screens on external doors and windows. A total of 10 treatment and 10 control clusters (100 houses/cluster) were distributed throughout the city of Merida, Mexico. Cross-sectional entomological surveys quantified indoor adult mosquito infestation at baseline (pre-intervention) and throughout four post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over two years (2012-2014). A total of 844 households from intervention clusters (86% coverage) were protected with ITS at the start of the trial. Significant reductions in the indoor presence and abundance of Ae. aegypti adults (OR = 0.48 and IRR = 0.45, P<0.05 respectively) and the indoor presence and abundance of Ae. aegypti female mosquitoes (OR = 0.47 and IRR = 0.44, P<0.05 respectively) were detected in intervention clusters compared to controls. This high level of protective effect was sustained for up to 24 months PI. Insecticidal activity of the ITS material declined with time, with ~70% mortality being demonstrated in susceptible mosquito cohorts up to 24 months after installation. The strong and sustained entomological impact observed in this study demonstrates the potential of house screening as a feasible, alternative approach to a sustained long-term impact on household infestations of Ae. aegypti. Larger trials quantifying the effectiveness of ITS on epidemiological endpoints are warranted and therefore recommended

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

Efectividad de repelentes comerciales disponibles contra el mosquito Aedes aegypti (L.) en Yucatán, México

Objetivo. Determinar la eficacia de repelentes comerciales disponibles en Yucatán contra el mosquito Aedes aegypti, vector del dengue, Chikungunya y Zika. Material y métodos. Se determinó el tiempo de protección con base en el protocolo WHO/CTD/WHOPES/IC y la NOM-032- SSA2-2014. Resultados. Sólo el repelente con DEET (N, N-dietil-3-metilbenzamida) al 25% cumplió con la protección recomendada. La eficacia fue directamente proporcional a la concentración del DEET; aquéllos con componentes botánicos fueron poco o nada protectores. Conclusiones. Los resultados muestran que los repelentes con DEET proveen protección contra Ae. Aegypti; los repelentes botánicos, incluyendo las pulseras impregnadas, ofrecen nula protección. ABSTRACT Objective. We assessed the efficacy of commercial repellents available in Yucatan against Aedes aegypti, vector of dengue, Chikungunya and Zika. Materials and methods. Protection time was determined based on WHO/CTD/ WHOPES/IC y la NOM-032-SSA2-2014. Results. Products with DEET (N, N-diethyl-3-methylbenzamide) at 25% met the recommended protection. Efficacy was directly proportional to the concentration of DEET; botanicals repellents resulted no protective. Conclusions. Repellents with DEET provided more protection against Ae. aegypti and botanical repellents, including impregnated wristbands, provided no protection

Efficacy of long-lasting insecticidal nets with declining physical and chemical integrity on Aedes aegypti (diptera : culicidae)

Fitting long-lasting insecticidal nets (LLIN) as screens on doors and windows has a significant impact on indoor adult Aedes aegypti, with entomological reductions measured in a previous study being significant for up to two years post-installation, even in the presence of pyrethroid-resistant Aedes populations. The study used bioassays (0, 6, and 12 months), which confirmed that LLIN residual activity decreased over time. However, the study demonstrates that the remaining chemical effect after field conditions still contributes to killing/repelling mosquitoes. LLIN screening from the neighborhood Juan Pablo II in Merida (Yucatan State, Mexico) were randomly selected. Merida is highly endemic for dengue and other Aedes-borne viruses

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