Journal of Vector Borne Diseases (Mar 2010)
The effects of climatic factors on the distribution and abundance of Japanese encephalitis vectors in Kurnool district of Andhra Pradesh, India
Abstract
Background & objectives: Climatic attributes have been associated with relative mosquito abundanceand transmission of mosquito borne infections in many parts of the world, especially in warm andtropical climatic regions. The main objectives of this study were to assess the change in seasonalpattern of Japanese encephalitis (JE) vectors, their density, to elucidate whether the lagged climatevariables (precipitation, temperature and humidity) are associated with JE vector density, and todetermine if temperature and precipitation are similarly important for the rise in the number ofpotential mosquito vectors for JE virus in the temperate climate of Andhra Pradesh, India.Methods: Mosquito samples were collected from Kurnool district of Andhra Pradesh using handcatch and light-trap methods during 2002 to 2006. The type and abundance of recovered specieswere compared to ecological correlates. In each geographic area, temperature and precipitationare the two possible proxy variables for mosquito density, in conjunction with other seasonalfactors for JE epidemics.Results: Out of the various mosquito species collected, Culex gelidus and Cx. tritaeniorhynchuswere noticed in high numbers. There was considerably high prevalence of Cx. gelidus (68.05%) inurban area than in rural areas whereas, Cx. tritaeniorhynchus (57.51%) was found to be more inrural areas than in the urban area. It is noticed that the factors such as rainfall and temperaturewere found to be correlated with the per man hour (PMH) density, whereas the humidity wasinversely correlated with the PMH.Interpretation & conclusion: The environmental and eco-climatic factors are assisting in enhancingthe breeding of these mosquitoes in Kurnool district of Andhra Pradesh, India. Both Cx.tritaeniorhyncus and Cx. gelidus are quite adaptable to these environmental conditions and thisnecessitates immediate control measures in both rural and urban areas of Kurnool district.
