Autor(es): Raharimalala Fara Nantenaina, Ravaomanarivo Lala Harivelo, Ravelon-ro Pierre, Rafarasoa Lala Sahondra, Zouache Karima, Tran-Van Van, Mousson Laurence, Failloux Anna-Bella, Hellard Eléonore, Moro Claire Valiente, Ralisoa Bakoly Olga, Mavingui Patrick

Resumo: In the past ten years, the Indian Ocean region has been the theatre of severe epidemics of chikungunya - dengue. These outbreaks coincided with a high increase in populations of Aedes albopictus that outcompete its sister taxon Aedes aegypti in most isl-s sampled. The objective of this work was to update the entomological survey of the two Aedes species in the isl- of Madagascar which has to face these arboviroses. The sampling of Aedes mosquitoes was conducted during two years, from October 2007 to October 2009, in fifteen localities from eight regions of contrasting climates. Captured adults were identified immediately whereas immature stages were bred until adult stage for determination. Phylogenetic analysis was performed using two mtDNA genes, COI - ND5 - trees were constructed by the maximum likelihood (ML) method with the gene time reversible (GTR) model. Experimental infections with the chikungunya virus strain 06.21 at a titer of 107.5 pfu/mL were performed to evaluate the vector competence of field-collected mosquitoes. Disseminated infection rates were measured fourteen days after infection by immunofluorescence assay performed on head squashes. The species Aedes aegypti was detected in only six sites in native forests - natural reserves. In contrast, the species Aedes albopictus was found in 13 out of the 15 sites sampled. Breeding sites were mostly found in man-made environments such as discarded containers, used tires, ab-oned buckets, coconuts, - bamboo cuts. Linear regression models showed that the abundance of Ae. albopictus was significantly influenced by the sampling region (F = 62.00, p < 2.2 × 10(-16)) - period (F = 36.22, p = 2.548 × 10(-13)), that are associated with ecological - climate variations. Phylogenetic analysis of the invasive Ae. albopictus distinguished haplotypes from South Asia - South America from those of Madagascar, but the markers used were not discriminant enough to discern Malagasy populations. The experimental oral infection method showed that six Ae. albopictus populations exhibited high dissemination infection rates for chikungunya virus ranging from 98 to 100%. In Madagascar, Ae. albopictus has extended its geographical distribution whereas, Ae. aegypti has become rare, contrasting with what was previously observed. Changes are predominantly driven by human activities - the rainfall regime that provide suitable breeding sites for the highly anthropophilic mosquito Ae. albopictus. Moreover, these populations were found to be highly susceptible to chikungunya virus. In the light of this study, Ae. albopictus may have been involved in the recent outbreaks of chikungunya - dengue epidemics in Madagascar, - consequently, control measures should be promoted to limit its current expansion.

Imprenta: Parasites & Vectors, v. 5, p. 56, 2012

Identificador do objeto digital: 10.1186/1756-3305-5-56

Descritores: Chikungunya virus - Arbovirus ; Chikungunya virus - DNA ; Chikungunya virus - Pathogenesis ; Chikungunya virus - Proteins ; Chikungunya virus - Molecular methods ; Chikungunya Virus - Virus ; Chikungunya virus - Dengue ; Chikungunya virus - Epidemic

Data de publicação: 2012

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