RESUMO
Arbovirus epidemics in a geographic region are believed to depend on the presence of susceptible or "competent" arthropod vectors. We demonstrate that an urban, Aedes aegypti-borne, epidemic of yellow fever occurred in 1987 although the mosquito vector was relatively resistant to infection and transmitted the virus inefficiently. Twenty-six percent of the experimental mosquitoes from the epidemic area that ingested yellow fever virus became infected and only 7% of these transmitted the virus. In contrast, 80% of an exotic susceptible strain of Ae. aegypti became infected and 43% were able to transmit. We also show that no other potential vectors were active during the epidemic and that the local Ae. aegypti were present in extremely large numbers. These results document, for the first time, that, in the presence of high population density an incompetent mosquito vector can initiate and maintain virus transmission resulting in an epidemic.
Assuntos
Aedes/microbiologia , Febre Amarela/epidemiologia , Adulto , Animais , Pré-Escolar , Surtos de Doenças , Vetores de Doenças , Feminino , Frequência do Gene , Inquéritos Epidemiológicos , Humanos , Lactente , Isoenzimas/genética , Nigéria/epidemiologia , Porto Rico/epidemiologia , População Urbana , Viremia/complicações , Viremia/epidemiologia , Viremia/genética , Febre Amarela/complicações , Febre Amarela/genética , Febre Amarela/transmissão , Vírus da Febre Amarela/genéticaRESUMO
Twenty-eight populations representing a worldwide distribution of Aedes aegypti were tested for their ability to become orally infected with yellow fever virus (YFV). Populations had been analyzed for genetic variations at 11 isozyme loci and assigned to one of 8 genetic geographic groups of Ae. aegypti. Infection rates suggest that populations showing isozyme genetic relatedness also demonstrate similarity to oral infection rates with YFV. The findings support the hypothesis that genetic variation exists for oral susceptibility to YFV in Ae. aegypti.
Assuntos
Aedes/microbiologia , Insetos Vetores/microbiologia , Vírus da Febre Amarela/crescimento & desenvolvimento , Aedes/enzimologia , Aedes/genética , África , Animais , Ásia , América Central , Feminino , Variação Genética , Isoenzimas/análise , Boca/microbiologia , América do Sul , Estados Unidos , Índias OcidentaisRESUMO
Twenty-eight populations representing a worldwide distribution of Aedes aegypti were tested for their ability to become orally infected with yellow fever virus (YFV). Populations had been analyzed for genetic variations at 11 isozyme loci and assigned to one of 8 genetic geographic groups of Ae. aegypti. Infection rates suggest that populations showing isozyme genetic relatedness also demonstrate similarity to oral infection rates with YFV. The findings support the hypothesis that genetic variation exists for oral susceptibility to YFV in Ae. aegypti.(AU)
Assuntos
Humanos , 21003 , Feminino , Aedes/microbiologia , Insetos Vetores/microbiologia , Vírus da Febre Amarela/crescimento & desenvolvimento , Aedes/enzimologia , África , Ásia , América Central , Estados Unidos , Variação Genética , Índias Ocidentais , Isoenzimas/análise , Boca/microbiologia , América do SulRESUMO
Using starch gel electrophoresis, we have analyzed genetic variation at 11 loci in 18 Caribbean collections of Aedes aegypti. Our results show that, while there is some relationship between geographic proximity and genetic distance, the overall picture among islands is one of gene frequency patchiness , with some collections clearly not conforming to any geographic pattern. We attribute this to the combined effects of high rates of gene flow among islands and with the mainland American continent, and the activities of various vector control agencies in the region.