ABSTRACT
Entomological investigations were carried out in areas affected by Japanese encephalitis (JE) in Mandya District, Karnataka, India, from 1983 to 1988, to determine species composition and the density of mosquito vectors, in relation to the incidence of JE cases. JE cases occurred in two spells in a year, one during April-June (summer epidemic) and another during October-December (winter epidemic). There was very high incidence of JE cases in extensively irrigated areas and a low incidence in some of the taluks with less or no irrigation systems. Among culicines, Culex tritaeniorhynchus was the most predominant species (20.54%), followed by Cx. fuscocephala (16.94), Cx. vishnui (16.48%), Cx. gelidus (10.70%) and other species. The overall mosquito population showed two peaks in a year, one during the March-April, and another during September, usually preceding the human epidemics. Relative abundance of certain species varied in different years.
Subject(s)
Animals , Culicidae/classification , Disease Reservoirs , Encephalitis Virus, Japanese , Encephalitis, Japanese/epidemiology , Humans , Incidence , India/epidemiology , Population Density , Prevalence , SeasonsABSTRACT
Domestic pigs were used as sentinels in Mandya district (Karnataka state) in India during 1984 to 1986 to monitor the activity of Japanese encephalitis (JE) virus in nature. Out of 213 sentinel pigs studied in 11 localities, 44 pigs placed at 5 localities showed seroconversion to Japanese encephalitis virus. A pig mosquito cycle, operating throughout the year appears to be one of the maintenance mechanisms of the virus in the study area in addition to the bird-mosquito cycle.