A comparative study of prevalence and spatial distribution of major Anopheline vector fauna in a hyper- and a hypomalaria endemic district of Odisha, India with special reference to onset of first wet season

ABSTRACT

@#The state’s retrospective findings indicate the incidence of malaria deaths, which is more during the onset of first monsoon season. Based upon this fact, our objective was to study the distribution pattern of major Anopheles vectors in two endemic districts viz. Kalahandi and Cuttack of Odisha, India that differ significantly according to malariogenic stratification, under the impact of first monsoon shower. A comparative study of vector abundance, predominance, their habitats, resting site preference, impact of abiotic rhythm (light/dark period) on vector distribution, gonotrophic status as well as sporozoite rate was established in a high and a low endemic district of Odisha, when the degree of malaria transmission elevates to its peak level Anopheles culicifacies was found to be predominant in hyperendemic Kalahandi district while Anopheles subpictus was abundant in hypo-endemic Cuttack district. Both primary vector An. culicifacies and the secondary vector An. subpictus mostly prefer CS (Cattle shed) compared to HD (Human dwelling) in Kalahandi district where as there was slight shifting of resting habitat of An. culicifacies from CS to HD in Cuttack district. Anopheles culicifacies prefers to rest on wall besides objects in Kalahandi while no such site preference was observed in Cuttack district. On the other hand, distribution of An. subpictus was highly influenced by the daily rhythm of light/dark cycle (i.e. day and night) in Cuttack. The gonotrophic condition revealed the high tendency of the predominant vectors towards endophilic resting. The sporozoite rate was 0.66% in Kalahandi and nil in Cuttack district. The proper monitoring of vector prevalence and distribution, at least during the peak transmission period can avert a perpetuated upsurge in malaria.