Improving Aedes aegypti control by enhancing community access to house-screening

Houses with house-screening (HS) compared to regular netting/unprotected households, had significatively lower risk for having Ae. aegypti female mosquitoes (OR=0.56, 95% C. I. 0.33-0.99) and blood-fed females (OR=0.53, 95% C. I. 0.28-0.97). All project participants were satisfied with the installation process and positive about the efficacy because of perceived significant reductions of mosquito in their houses (>80%). All participants recommended scaling up of the intervention. The technical report provides details of screen installation, participant perspectives, project implementation, cost-benefit analysis and findings. Urban improvements that reduce mosquito populations, especially disease vectors are an important component of sustainable development. The report is in English and Spanish

Prevalência de pediculose em crianças de escola rural em Yucatan, Mexico

We conducted an analytical cross-sectional survey to estimate the prevalence of and factors associated with active head lice infestation. In total 140 children, aged 6 to 16-years, from a public school in rural Yucatan, Mexico, were examined by wet-combing. A structured questionnaire was used to collect information on individuals and the conditions in the surrounding environment. Head lice infestation was found in 19 out of the 140 children tested (13.6%) and this was associated with both lower income (OR 9.9, 95% CI 2.15-45.79, p = 0.003) and a higher frequency of hair washing (OR 8, 95% CI 1.58-50, p = 0.012). Intersectoral control programs that take into account the socioeconomic differences of children should be implemented.Foi conduzido um estudo numa escola publica de área rural em Yucatan, Mexico com o objetivo de estimar a prevalência de pediculose e fatores de risco associados. Das 140 crianças incluídas 19 (13.6%) apresentaram pediculose. A infestação de piolho foi associada com baixa renda (OR 9.9, 95% CI 2.15-45.79, p = 0.003) e maior frequência de lavagem de cabelos (OR 8, 95% CI 1.58-50, p = 0.012). Programas intersetoriais de controle da pediculose que levam em conta as características socioeconômicas das crianças deveriam ser executados

Challenges for the Introduction and Evaluation of the Impact of Innovative Aedes aegypti Control Strategies

Innovative control tools for the dengue, chikungunya and Zika vector Aedes aegypti, such as genetically modified mosquitoes and biological control and manipulation with the bacteria Wolbachia, are now becoming available and their incorporation into institutional vector control programs is imminent. The objective of this chapter is to examine the technical and organizational mechanisms together with the necessary processes for their introduction and implementation, as well as the indispensable indicators to measure their entomological effect on vector populations and their epidemiological impact in the short, medium and long term as part of an integrated vector management approach

Clinical Manifestations in Pregnant Women and Congenital Abnormalities in Fetus and Newborns during a Zika Transmission Period in South Mexico

Dengue, Chikungunya and Zika are arboviruses transmitted by Ae. aegypti with significant public health impact. In the first trimester of 2015, autochthonous Zika transmission was reported in Mexico. The state of Yucatan is an endemic region where pregnant women with acute infection and related congenital abnormalities in fetus and newborns were observed. We describe results from a cohort of pregnant women and their babies followed up in Yucatan during the first Zika transmission outbreak (2016–2018). Clinical manifestations of acute ZIKV infection, persistence of viral RNA in pregnant women, as well as congenital abnormalities were observed. In addition, we describe the phenotype of newborns from confirmed or suspected ZIKV prenatal infection

Seroprevalence of dengue antibodies in three urban settings in Yucatan, Mexico

Dengue transmission in Mexico has become a major public health problem. Few epidemiological studies have examined the seroprevalence of dengue in Mexico, and recent estimates are needed to better understand dengue transmission dynamics.Weconducted a dengue seroprevalence survey among 1,668 individuals including all age groups in three urban settings in Yucatan, Mexico. Children (< 19 years old) were selected randomly from schools. The adults (≥ 19 years old) were selected from healthcare facilities. Participants were asked to provide a venous blood sample and to answer a brief questionnaire with demographic information. Previous exposure to dengue was determined using indirect immunoglobulin G enzyme-linked immunosorbent assay. The overall seroprevalence was 73.6%. The age-specific seroprevalence increased with age, going from 51.4% (95% confidence interval [CI] = 45.0-57.9%) in children ≤ 8 years to 72% (95% CI = 66.3-77.2%) in the 9- to 14-years old. The highest seroprevalence was 83.4% (95% CI = 77-82.2%) in adults greater than 50 years. The seroprevalence in Merida was 68.6% (95% CI = 65-72%), in Progreso 68.7% (95% CI = 64.2-72.8%), and in Ticul 85.3% (95% CI = 81.9-88.3%). Ticul had the highest seroprevalence in all age groups. Logistic regression analysis showed that age and city of residence were associated with greater risk of prior dengue exposure. The results highlight the level of past exposure to dengue virus including young children. Similar studies should be conducted elsewhere in Mexico and other endemic countries to better understand the transmission dynamics of deng

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

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

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