Life table characteristics and vector competence of field populations of Aedes aegypti for Chikungunya virus in Argentina

MICIELI. M.V; CHIN, PAM; BALSALOBRE A; MUTTIS E; GAUTO N; NANGUDO, CAROLINA; KRAMER L

Maryland, Washington, D.C.

Workshop; Workshop: Gaps and Opportunities in Chikungunya Research: Expert Consultation on Chikungunya Disease in the Americas; 2015

The National Institute of Allergy and Infectious Diseases of the National Institutes of Health of the U.S. Department of Health and Human Services (NIAID/NIH/HHS) in partnership with the Pan American Health Organization (PAHO/WHO) and the World Health

Chikungunya virus (Togaviridae; Alphavirus) was introduced into the Caribbean in October 2013 and subsequently expanded its range to Central and South America as well as the United States. Endemic transmission of the virus has not yet been detected in Argentina, although there have been imported cases and the virus is indigenous now in neighboring Brazil. The predominant vector implicated in CHIKV transmission in the western hemisphere is Aedes aegypti. This species is found predominantly from the northeastern province of Misiones south to Buenos Aires. We conducted a comprehensive study in 2014 on Ae. aegypti in Argentina over the extent of this geographic range. The project focuses on how local cycling temperatures and genetic variation in natural populations of Ae. aegypti impact life history traits of this mosquito, as well as its ability to transmit Chikungunya (and Dengue viruses). Ae. aegypti is known to have considerable genetic, behavioral, and ecological variation that is often spatially and/or temporally heterogeneous. The genetic variation observed in Argentina is most likely a consequence of multiple introductions leading to heterogeneity in a large number of traits: morphology, ecology, genetics, behavior, and ability to transmit arboviruses. We collected Ae. aegypti from reported genetically distinct populations in Argentina, from containers around homes, tires, cemeteries, and other temporary sources in four locations ranging from subtropical Iguazu and Posadas in the north to temperate Buenos Aires in the south, and Salta in the northwest. The mosquitoes were reared to the first generation of adults in the laboratory, then blood fed for F1- F2 eggs, which were hatched to determine life table characteristics and vector competence at the natural cycling temperatures recorded in each of the study sites. The genetic analyses used nine microsatellite loci and two mitochondrial DNA regions (COI and ND4), as were successfully used to determine phylogeny of Bolivian Ae.aegypti. Life table studies included development time, survivorship, fecundity at the 4 sets of cycling temperatures. The experiments have been completed and the results are currently being analyzed.