Background: Western Rajasthan of India has a typical desert climate. Until the introduction of canal water irrigation system, malaria was an unstable and seasonal occurrence. Due to scarcity of water, community practiced to have one large underground tank (locally known as Tanka) in their house to store water for long term use. Anopheles stephensi, one of the major malaria vectors, breeds in these "Tankas” if not properly covered and harbor a vector population throughout the year.
Methods: Two villages Ajasar (intervention) and Tota (control) with similar ecological features were selected for the study. A pre-assessment was carried out in both villages to assess lids of Tankas, their breeding profile and the adult mosquito density. Awareness of community about malaria and mosquitoes was also assessed during pre-assessment period. In intervention village, lids were replaced with improved polyvinyl lids that were mosquito proof and last longer than conventional lids. Fitness of the lids, was assessed after one year. Entomological assessment was carried out in both intervention and non-intervention villages. The level of awareness of community was assessed both during pre and post intervention.
Results : During the pre-assessment, Anopheles breeding was found in 22.1% (58/262) of Tankas of intervention village and 27.1% (19/70) of Tankas of control village. Tankas with iron lids were mainly positive in the intervention village (48.3%) and the control village (42.1%). In intervention village, 200 lids were replaced, and zero positivity was achieved.
Before intervention, the species composition of An. stephensi was 46% in intervention and 55% in control village. Per Man Hour Density (PMHD) of An. stephensi was significantly reduced to 0.55 (94.95%) and 0.22 (97.8%) in post-intervention and follow-up, respectively in intervention village.
Discussion: The adult density of An. stephensi was reduced significantly (97.8%) in intervention village. Breeding in underground tankas was completely checked in intervention village as compared to the control, where no such substantial reduction was observed. The awareness level of the community was also improved due to their involvement in the study.
Conclusion: The study demonstrated that the small changes and interventions to reduce mosquitogenic conditions can be cost effective and long-lasting which may be helpful in control of malaria.