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

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

The risk of Aedes aegypti breeding and premises condition in South Mexico.

A recent innovation instrumented for the Dengue Prevention and Control program in Mexico is the use of the premises condition index (PCI) as an indicator of risk for the vector Aedes aegypti infestation in dengue-endemic localities of Mexico. This paper addresses whether further improvements for the dengue control program could be made if the prevalence and productivity of Ae. aegypti populations could be reliably predicted using PCI at the household level, as well as medium-sized neighborhoods. We evaluated the use of PCI to predict the infestation with Aedes aegypti (breeding sites and immature productivity) in Merida, Mexico. The study consisted of a cross-sectional survey based on a cluster-randomized sampling design. We analyzed the statistical association between Aedes infestation and PCI, the extent to which the 3 components of PCI (house maintenance, and tidiness and shading of the patio) contributed to the association between PCI and infestation and whether infestation in a given premises was also affected by the PCI of the surrounding ones. Premises with the lowest PCI had significantly lower Aedes infestation and productivity; and as PCI scores increased infestation levels also tended to increase. Household PCI was significantly associated with Ae. aegypti breeding, largely due to the effect of patio untidiness and patio shade. The mean PCI within the surroundings premises also had a significant and independent explanatory power to predict the risk for infestation, in addition to individual PCI. This is the 1st study in Mexico showing evidence that premises condition as measured by the PCI is related to Ae. aegypti breeding sites and immature productivity. Results suggest that PCI could be used to streamline surveys to inform control efforts at least where Ae. aegypti breeds outdoors, as in Merida. The effect of individual premises, neighborhood condition, and the risk of Aedes infestation imply that the risk for dengue vector infestation can only be minimized by the mass effect at the community level

Interruption of Transmission of <i>Onchocerca volvulus</i> in the Southern Chiapas Focus, México

<div><p>Background</p><p>The Southern Chiapas focus of onchocerciasis in Southern Mexico represents one of the major onchocerciasis foci in Latin America. All 559 endemic communities of this focus have undergone semi-annual mass treatment with ivermectin since 1998. In 50 communities of this focus, ivermectin frequency shifted from twice to four times a year in 2003; an additional 113 communities were added to the quarterly treatment regimen in 2009 to achieve a rapid suppression of transmission.</p> <p>Methodology/Principal findings</p><p>In-depth epidemiologic and entomologic assessments were performed in six sentinel communities (which had undergone 2 rounds of ivermectin treatment per year) and three extra-sentinel communities (which had undergone 4 rounds of ivermectin treatment per year). None of the 67,924 <i>Simulium ochraceum</i> s.l. collected from this focus during the dry season of 2011 were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the 95% confidence interval (95%-ULCI) of the infective rate in the vectors of 0.06/2,000 flies examined. Serological assays testing for <i>Onchocerca volvulus</i> exposure conducted on 4,230 children 5 years of age and under (of a total population of 10,280 in this age group) revealed that 2/4,230 individuals were exposed to <i>O. volvulus</i> (0.05%; one sided 95% confidence interval = 0.08%).</p> <p>Conclusions/Significance</p><p>The in-depth epidemiological and entomological findings from the Southern Chiapas focus meet the criteria for interruption of transmission developed by the international community.</p> </div

Coverage rate with ivermectin of the eligible population of the Southern Chiapas focus.

<p>The coverage rate, expressed in percent and the 95%-confidence intervals, CIs, surrounding point estimate, with ivermectin of the eligible population of the Southern Chiapas focus, 1995–2011. The line at 85% indicates the coverage needed in a sustained fashion to interrupt transmission.</p

Prevalence of IgG4 antibodies to Ov16 in the focus of Southern Chiapas, México.

<p>Prevalence of IgG4 antibodies to Ov16 in children 10 years of age and under from sentinel, extra-sentinel, and eight other communities, in migrant workers >15 years of age from three coffee fincas and in children 5 years of age and under from 4 districts in the focus of Southern Chiapas, México.</p>*<p>Skin biopsies were taken and tested by PCR; they contained no parasite DNA (unpublished data).</p

In-depth epidemiologic assessments in sentinel and extra-sentinel communities of the Southern Chiapas focus.

<p>In-depth epidemiologic assessments in sentinel and extra-sentinel communities of the Southern Chiapas focus.</p

Map of the Southern Chiapas focus, México.

<p>The map of the Southern Chiapas focus shows the six sentinel (marked in yellow) and three extra-sentinel communities (marked in red) and the main rivers and tributaries that might serve as a source of black fly breeding. Map (right) of the Southern Mexico states showing the three onchocerciasis endemic foci.</p

Number of individuals with nodules in the Southern Chiapas focus, Mexico, 1995–2010.

<p>Number of individuals with nodules in the Southern Chiapas focus, Mexico, 1995–2010.</p