Session

Session “Aedes aegypti genetics for vector control” How distinct is the neglected dengue virus circulation among Aedes aegypti mosquitoes Taissa Pereira dos Santos1, Flávia Barreto dos Santos2, Márcia Gonçalves de Castro1, Ricardo Lourenço-de-Oliveira1 1

2

Laboratório de Transmissores de Hematozoários, Laboratório de Flavivírus, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.

In 2013, Rio de Janeiro reported a dengue outbreak with 213,420 cases. The number of dengue cases peaked in March-April 2013, being more than 95% of the laboratory confirmed cases due to DENV-4. A total of 2,822 adult Ae. aegypti caught all over the city during the period comprising the epidemics (November 2012 to July 2013) were pooled and examined by RTPCR: 2,13% of tested pools were positive. When mosquitoes composing each positive pool were individually tested by RT-PCR, a DENV infection rate of 0.95% was found. All positive mosquitoes were females, except for one positive male. The peak of DENV positive mosquito pools was registered in March 2013, and coincided with that of human dengue cases. However, the frequency of DENV serotypes detected in Ae. aegypti was intriguingly differed from that found in humans. DENV-2 was the most frequently detected serotype (37.0%) in mosquitoes, followed by DENV 1 (25.9%), DENV 3 e DENV 4 (both 18.5%). One Ae. aegypti female was simultaneously infected with DENV-1 and DENV-4. The divergence between the frequency of infections by DENV serotypes in mosquitoes and humans and the detection of positive Ae. aegypti male suggest the occurrence of silent transmission maintenance of DENV serotypes among mosquitoes that can emerge/reemerge as human epidemic at any time, depending on local epidemiological and ecological circumstances. Therefore, entomological and virological surveillances must be continuous in endemic sites.

Genetics diversity and population structure of Aedes aegypti from Cape Verde (West african): A temporal survey Célia Serrano1, Joana Alves2,3, Bruno Gomes1,2, João Pinto1,2, Carla A. Sousa1,4, Patrícia Salgueiro1 1

2

UEI Parasitologia Médica, IHMT, UNL, Lisboa, Portugal; Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de 3 Lisboa (UNL), Lisboa, Portugal; Direção Geral de Saúde, Ministério da Saúde de Cabo 4 Verde ; Unidade de Parasitologia e Microbiologia Médicas, IHMT, UNL, Lisboa, Portugal.

Background: Aedes aegypti is the mosquito vector of dengue, the most significant mosquitoborne viral diseases in the world. Due to the lack of antiviral therapy or vaccination, reducing dengue transmission depends only on mosquito control. In the archipelago of Cape Verde (West Africa) in November 2009 a dengue epidemic was declared with more than 20000 people affected and six deaths. The presence of A. aegypti in the archipelago was reported since 1931. Objectives: To evaluate the genetic variability and effective population size of A. aegypti populations from Cape Verde before and after the dengue outbreak.

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Amazonian Conference on Emerging and Infectious Diseases - Cayenne – September 2014

Methods: We analysed two mosquito samples from Santiago island collected before and after the dengue outbreak (N=47 in 2007 and N=24 in 2010, respectively) and genotyped them for 14 microsatellites. Parameters of genetic diversity and population differentiation were assessed with the softwares Genepop and Arlequin 3.5. NeEstimator and Bottleneck softwares were used to estimate effective population size (Ne) and detect population changes, respectively. We also used a Bayesian clustering method (software Structure) to evaluate patterns of population structure. Results: Mean over loci allelic richness and expected heterozygosity was 5 and 0.7, respectively in both temporal samples. Ne was smaller in 2010 (Ne=16) than in 2007 (Ne=8), and we detected a bottleneck effect in 2010. The two samples were significantly differentiated, and Bayesian clustering analysis detected two clusters (k=2) corresponding to each temporal sample. Conclusion: We have found comparable levels of genetic diversity between collection years, within the range of values for other African populations. However, there was significant intertemporal genetic differentiation associated with a signal of population bottleneck and a reduction in effective population size. Results will be discussed with respect to the epidemiology of dengue and control efforts in the archipelago.

Aedes aegypti and the Dengue outbreak in Madeira island: the burden of a recent colonisation Gonçalo Seixas1, Patrícia Salgueiro1, Gonçalo Alves2, Ana C. Silva3, Maria T. Novo2, João Pinto1* & Carla A. Sousa2 1.

Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, 2. Universidade Nova de Lisboa, Lisboa, Portugal. Unidade de Parasitologia e Microbiologia Médicas, Instituto de Higiene e Medicina Tropical, Universidade Nova de 3. Lisboa, Lisboa, Portugal. Instituto de Administração de Saúde e Assuntos Sociais (IASAUDE), Funchal, Madeira, Portugal.

In 2005, The Institute of Hygiene and Tropical Medicine received from the Natural History Museum of Madeira a sample of mosquitoes collected in the island, following complaints of the local inhabitants about a highly nuisance mosquito. These mosquitoes were identified as Aedes aegypti, the first report of this important arbovirus vector in the island. After this report, it took less than 8 years until a Dengue epidemic occurred in the island. The first cases were detected in October 2012 and the epidemic lasted for 20 weeks counting over 2,000 reported cases with no fatalities. Since 2009, IHMT has been participating in the monitoring of A. aegypti in Madeira. Studies involve monitoring of mosquito dispersal and abundance, bioecological characterizations, insecticide resistance profiling and genetic analyses. Here we present an update of the ongoing studies, with emphasis on the levels of insecticide resistance and its mechanisms, and molecular genetic analysis aiming at establishing the origin of this mosquito population. Insecticide susceptibility assays have shown a highly resistant A. aegypti population with mortality rates below 80% for pyrethroid and organochlorine (DDT) insecticides. Genetic analysis of the voltage-gated sodium channel gene revealed a high frequency of the knockdown resistance (kdr) associated mutation F1534C. An additional mutation, V1016I, was also detected at frequencies up to 23%. Phylogenetic analysis based on mtDNA genes suggest a South American origin for this vector population, possibly from Brazil or Venezuela, two countries with important migrant flows with Madeira island.

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Amazonian Conference on Emerging and Infectious Diseases - Cayenne – September 2014