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Eisen L.,Colorado State University | Garcia-Rejon J.E.,Autonomous University of Yucatan | Gomez-Carro S.,Servicios de Salud de Yucatan | Vazquez M.D.R.N.,Servicios de Salud de Yucatan | And 3 more authors.
Journal of Medical Entomology | Year: 2014

Surveillance of dengue virus (DENV) in Aedes (Stegomyia) aegypti (L.) females is of potential interest because human DENV infections are commonly asymptomatic, which decreases the effectiveness of dengue case surveillance to provide early warning of building outbreaks. Our primary aim was to examine if mosquito-based virological measures-monthly percentages of examined Ae. aegypti females infected with DENV or examined homes from which at least one DENV-infected Ae. aegypti female was collected-are correlated with reported dengue cases in the same or subsequent months within study neighborhoods in Mérida City, México. The study encompassed ≈30 neighborhoods in the southern and eastern parts of the city. Mosquitoes were collected monthly over a 15-mo period within study homes (average of 145 homes examined per month); this produced ≈5,800 Ae. aegypti females subsequently examined for DENV RNA. Although monthly dengue case numbers in the study neighborhoods varied >100-fold during the study period, we did not find statistically significant positive correlations between monthly data for mosquito-based DENV surveillance measures and reported dengue cases in the same or subsequent months. Monthly average temperature, rainfall, and indoor abundance of Ae. aegypti females were positively correlated (P ≤ 0.001) with dengue case numbers in subsequent months with lag times of 3-5, 2, and 1-2 mo, respectively. However, because dengue outbreak risk is strongly influenced by serotype-specific susceptibility of the human population to DENV, the value of weather conditions and entomological indices to predict outbreaks is very limited. Potential ways to improve the sensitivity of mosquito-based DENV surveillance are discussed. © 2014 Entomological Society of America.

Manrique-Saide P.,Autonomous University of Yucatan | Arisqueta-Chable C.,Autonomous University of Yucatan | Geded-Moreno E.,Autonomous University of Yucatan | Herrera-Bojorquez J.,Autonomous University of Yucatan | And 5 more authors.
Journal of the American Mosquito Control Association | Year: 2013

We compared the number of adult Aedes aegypti emerging from subsurface catch basins located in the streets against the number of pupae (as a proxy of adults emerging) from the entire container larval habitats found at residential premises within 1 ha of a neighborhood in the Mexican city of Merida during 8 days in the dry season of 2012. Aedes aegypti adults were collected from 60% of the subsurface catch basins. They produced 12 adults/day/ha (95% confidence interval CI, 6.4 to 17.9), 5 females (95% CI, 2.1 to 7.7), and 7 males (95% CI, 3.8 to 10.7). In contrast, only 7 containers holding water were identified in 30 premises inspected, 1 bucket was positive for Ae. aegypti larvae, but no pupae-positive containers were found. No other mosquito species were found. This study revealed the importance of this type of nonresidential and subterranean aquatic habitat for Ae. aegypti adult production in this neighborhood of Merida during the dry season. © 2013 by The American Mosquito Control Association, Inc.

Manrique-Saide P.,Autonomous University of Yucatan | Che-Mendoza A.,Servicios de Salud de Yucatan | Barrera-Perez M.,Autonomous University of Yucatan | Guillermo-May G.,Autonomous University of Yucatan | And 7 more authors.
Emerging Infectious Diseases | Year: 2015

Dengue prevention efforts rely on control of virus vectors. We investigated use of insecticide-treated screens permanently affixed to windows and doors in Mexico and found that the screens significantly reduced infestations of Aedes aegypti mosquitoes in treated houses. Our findings demonstrate the value of this method for dengue virus vector control. © Centers for Disease Control and Prevention (CDC). All rights reserved.

Che-Mendoza A.,Servicios de Salud de Yucatan | Guillermo-May G.,Autonomous University of Yucatan | Herrera-Bojorquez J.,Autonomous University of Yucatan | Barrera-Perez M.,Autonomous University of Yucatan | And 7 more authors.
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2014

Background: Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Methods: Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. Results: LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. Conclusions: These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. © The author 2015.

Deming R.,Emory University | Manrique-Saide P.,Autonomous University of Yucatan | Medina Barreiro A.,Autonomous University of Yucatan | Cardena E.U.K.,Autonomous University of Yucatan | And 6 more authors.
Parasites and Vectors | Year: 2016

Background: Dengue is a major public health problem in Mexico, where the use of chemical insecticides to control the principal dengue vector, Aedes aegypti, is widespread. Resistance to insecticides has been reported in multiple sites, and the frequency of kdr mutations associated with pyrethroid resistance has increased rapidly in recent years. In the present study, we characterized patterns of insecticide resistance in Ae. aegypti populations in five small towns surrounding the city of Merida, Mexico. Methods: A cross-sectional, entomological survey was performed between June and August 2013 in 250 houses in each of the five towns. Indoor resting adult mosquitoes were collected in all houses and four ovitraps were placed in each study block. CDC bottle bioassays were conducted using F0-F2 individuals reared from the ovitraps and kdr allele (Ile1016 and Cys1534) frequencies were determined. Results: High, but varying, levels of resistance to chorpyrifos-ethyl was detected in all study towns, complete susceptibility to bendiocarb in all except one town, and variations in resistance to deltamethrin between towns, ranging from 63-88 % mortality. Significant associations were detected between deltamethrin resistance and the presence of both kdr alleles. Phenotypic resistance was highly predictive of the presence of both alleles, however, not all mosquitoes containing a mutant allele were phenotypically resistant. An analysis of genotypic differentiation (exact G test) between the five towns based on the adult female Ae. aegypti collected from inside houses showed highly significant differences (p < 0.0001) between genotypes for both loci. When this was further analyzed to look for fine scale differences at the block level within towns, genotypic differentiation was significant for both loci in San Lorenzo (Ile1016, p = 0.018 and Cys1534, p = 0.007) and for Ile1016 in Acanceh (p = 0.013) and Conkal (p = 0.031). Conclusions: The results from this study suggest that 3 years after switching chemical groups, deltamethrin resistance and a high frequency of kdr alleles persisted in Ae. aegypti populations. The spatial variation that was detected in both resistance phenotypes and genotypes has practical implications, both for vector control operations as well as insecticide resistance management strategies. © 2016 Deming et al.

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