Entomological studies in a dengue endemic area, Jalore, Rajasthan

Entomological studies on prevalence of adult and immatures of Aedes aegypti along with associated ecological factors have been conducted in a dengue endemic area of Jalore, Rajasthan from 1992 to 1993. Studies in two areas; reportedly affected and unaffected revealed more adults and higher breeding indices in the affected area as compared to the unaffected one. Mosquitoes harbouring dengue antigen were found only in the affected locality. Presence of dengue antigen in field caught mosquitoes in the affected locality was observed mainly during the months of January to April in both the years. Statistical analysis of data has shown a correlation to be significant between adult house index and breeding index in the affected area while this association was found insignificant in the unaffected locality. Water storage practices of the population due to irregular water supply in the affected area is the possible cause for a higher vector concentration in the locality. Seasonality of occurrence of dengue fever patients in a particular period of the year is associated with a relatively higher vector density and the presence of infected mosquitoes which is due to favourable temperature, relative humidity, water temperature and pH.