Anopheline mosquitoes in District Ramgarh (Jharkhand), India

Background & objectives: Jharkhand is one of the highly malaria endemic states in India and experiencing vast ecological and human-induced changes over the years. These changes have provided more favourable conditions for malaria transmission in the region. The present study was carried out to find out the distribution and prevalence of anopheline vector and non-vector species in District Ramgarh of Jharkhand state. Methods: Daytime indoor resting adult female anopheline mosquitoes were collected from four subcentres comprising of eight study villages in District Ramgarh. The collections were made from fixed as well as random human dwellings and cattlesheds on fortnightly basis using manual aspiration method from January to December 2012. Mosquito identification was done by using standard identification keys. Results: A total of 18,875 anophelines belonging to 19 species were collected. Of these, 61.87% were vector species (An. culicifacies, An. fluviatilis and An. annularis). Of total vector collection, 57.44% was observed in Gola block and 42.55% in Ramgarh. An. culicifacies was predominant species followed by An. fluviatilis and An. annularis in the study area. Out of 19, eight anopheline species exhibited successional changes in their composition over the period of years. Statistical analysis revealed positive correlation between meteorological variables and man hour density in case of An. culicifacies, whereas these were negatively correlated in case of An. fluviatilis and An. annularis. Interpretation & conclusion: The study revealed the prevalence of three recognised malaria vector species (An. culicifacies, An. fluviatilis and An. annularis) in high density throughout the year in this area, which indicates possibility of widening of malaria transmission window in the presence of malaria parasites. The shifting of anopheline species in Ramgarh also indicate alteration in ecological, environmental and sociological conditions, which necessitate routine monitoring on ecology and successional changes of vector species as well as malariological survey for management and adoption of appropriate vector control strategies in this area