Distribution and seasonality of horizontally transmitted dengue viruses in aedes mosquitoes in a Metropolitan city Lahore, Pakistan

Abstract

Transovarial transmission of dengue viruses is a crucial phenomenon responsible for persistence of the viruses during inter-epidemic period (s) of the disease. In the present study, distribution and seasonality of horizontally transmitted dengue viruses in Aedes mosquitoes was investigated in the metropolitan city Lahore, Pakistan during 2011, 2012 and 2013. Adult Aedes aegypti, were captured from nine towns and one Cantonment Board of the city using back-pack mechanical aspirator. Female mosquitoes were segregated and were pooled (7-9 individuals/pool) and subjected to NS1 Antigen test (ELISA). To determine infectivity in a mosquito population, detection of the viruses in adult mosquitoes was used to calculate Minimum Infection Rate (MIR). Average MIR was highest being 3.52 and 2.94 in late rainy season in 2011 and 2012, respectively, while it was highest (3.06) in early post rainy season in 2013. Results also revealed significant correlation coefficient ‘r’ and coefficient of determination r 2 of MIR with air temperature in all seasons, strongest in early post-rainy season while with humidity and rainfall; these were significant in only early rainy and early post rainy seasons. It was concluded that higher MIR in mosquitoes indicated increased infectivity in them.