Natural mortality of Mansonia annulifera with special reference to mortality due to Brugia malayi infection and distribution of parasites in a vector population.
The natural mortality of M. annulifera mosquitoes was estimated at Shertallai Taluk, Kerala, India. Mortality of infected M. annulifera was higher than that of uninfected mosquitoes in all seasons. Linear regression analysis of the number of infections by age showed a close fit of observed to expected values estimated by the linear regression equation. A similar pattern was observed with the number of infected parous mosquitoes by age. Nearly 1.1% of feeds on man established B. malayi infection and the daily probability of survival among infected mosquitoes was found to be 85%. The extrinsic incubation period for B. malayi was calculated to be 7 days. The prevalence of infection varied significantly with vector age. Analysis of the parasite distribution in the vector population showed that the proportion of vectors with a high parasite load was low and that the distribution became less overdispersed with parasite stage.