The A. aegypti populations distributed in Brazil would have at least two different origins. That is demonstrated by the genetic analysis performed on mosquitoes from four different geographic regions in the country.

The study, carried out by researchers from the National Institute for Research in the Amazon (INPA), consisted in the genetic analysis of specimens of A. aegypti, the mosquito that transmits the dengue and yellow fever, using specimens collected from 14 areas in four different geographic regions of Brazil (northern, northeastern, southeastern and central).

The genetic sequence analyzed consisted of a region of mitochondrial DNA that codifies for the cytochrome oxidase I gen. Two well-differentiated lineages were identified and related to the Eastern and Western African genotypes. Besides, the analysis of the genetic and geographic distances suggests multiple introductions associated with several factors like passive dispersion patterns, control actions, extinction and recolonization events and genetic drift.

The results of this study, published in the June issue of the American Journal of Tropic Medicine and Hygiene, would provide a first line of evidence tending to understand phenomena of epidemiological importance, such as the presence of A. aegypti populations that respond differently to the control actions, due to the fact that they possess variable degrees of resistance to the products used in the programs, as well as to the differences in the competence to transmit the dengue and yellow fever viruses.


Source: Scarpassa VM, Cardoza TB, Cardoso, Junior RP. Population Genetics and Phylogeography of Aedes aegypti (Diptera: Culicidae) from Brazil. Am J Trop Med Hyg 2008 78: 895-903.