Evidence of vertical transmission and co-circulation of chikungunya and dengue viruses in field populations of Aedes aegypti (L.) from Guerrero, Mexico.

BACKGROUND: We report results of the entomo-virological surveillance system in Aedes aegypti local populations performed by the Ministry of Health of Guerrero. METHODS: Indoor-adult Ae. aegypti collected at Acapulco, Zihuatanejo, Coyuca de Benitez and Atoyac de Alvarez (dry season, 2015) were processed for dengue virus (DENV) and chikungunya virus (CHIKV) using RT-PCR. RESULTS: We identified different seroptypes of DENV (2, 3 and 4), CHIKV and their co-circulation in field-caught mosquitoes across a significant geographic area. Pools of males were positive for CHIKV and DENV 3 and 4 suggesting vertical transmission. CONCLUSIONS: Entomo-virological surveillance in Guerrero has identified early circulation of CHIKV and DENV and provided a trigger for timely and focalized vector control actions.

Arbovirus Surveillance and First Report of Chikungunya Virus in Wild Populations of Aedes aegypti from Guerrero, Mexico.

We carried out dengue (DENV) and chikungunya virus (CHIKV) surveillance in wild populations of Aedes aegypti from Guerrero, Mexico, from 2012 to 2014 following a standard national protocol of the Mexican Dengue Control Program. A total of 284 pools (15-30 specimens/pool) of female mosquitoes were tested with real-time reverse transcriptase-polymerase chain reaction to detect DENV and CHIKV. We report for the 1st time the detection of CHIKV from field-collected mosquitoes at Acapulco and Juchitán in 2014. Results from DENV are also reported.

Use of insecticide-treated house screens to reduce infestations of dengue virus vectors, Mexico.

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.

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico.

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.

Natural vertical transmission of dengue-1 virus in Aedes aegypti populations in Acapulco, Mexico.

We carried out dengue virus surveillance in Aedes aegypti populations from 47 neighborhoods of Acapulco during the rainy season of 2011 following a standard national protocol and as an improvement of the entomological surveillance of the Mexican Dengue Control Program. A total of 4,146 Ae. aegypti adults collected indoors and/or emerged from eggs, larvae, or pupae from households with dengue reports (probable or confirmed cases), were grouped into pools and processed using a standardized serotype-specific 4-plex real-time reverse transcriptase-polymerase chain reaction assay. Overall, only 2 (0.9%) of 226 pools of Ae. aegypti adults (1 pool of adults emerged from field-collected larvae, and another of indoor-collected adults) were positive for dengue virus 1 (DENV-1). This is appears to be the 1st report of evidence on the vertical and transovarial transmission of DENV-1 in field-caught Ae. aegypti in Mexico.