Estivation of Malaria Vector Mosquitoes in the Sahelian Region of Mali (Village of Thierola in the District of Banamba)

Detailed Summary

Background: * P. falciparum, one of the most virulent forms of malaria, causes more than 300 million episodes of malaria and 1 million deaths each year. The spread of drug-resistant parasites, insecticide-resistant mosquitoes, and persistent socioeconomic conditions of poverty compound the difficulties of malaria as a major global health problem. New means of disease and vector control are vitally needed. * Several promising strategies rely on targeting mosquito populations when they are most vulnerable, such as during the dry season when mosquitoes find it difficult to reproduce. Large regions of the West African country of Mali have prolonged dry seasons (up to 8 months), during which mosquito populations dramatically decline within a month after the rainfall ceases. Clearly, mosquitoes can survive the dry season (as evident from their robust numbers during the wet season) but the process that enables them to do so remains unknown. Targeting the small and fragile mosquito population at the end of the dry season could reduce or eliminate the numbers of mosquitoes in certain regions, providing great benefits for communities in dry regions. Objectives: * To determine if common malaria-carrying mosquitoes survive the dry season in the Mali village of Thierola by estivation (going dormant, or hibernating, during dry periods). * To identify and examine mosquitoes that were marked with special paint during a previous protocol, if these marked mosquitoes are captured during the investigation. Eligibility: * All activities in this protocol will take place in Thierola village, Banamba district, Koulikoro region, Mall, West Africa. The village was chosen because it is isolated from other communities by at least 6 km and is a small community of less than 300 inhabitants living in 90 houses. * Participants will be healthy adult men between 18 and 65 years of age. Design: * Thirty adult men who live in Thierola will be recruited to participate as mosquito collectors for the human-baited trapping method and will work in teams of two. * The first collector will expose his lower legs to attract human-seeking mosquitoes. Using a mouth aspirator, the second collector will collect the mosquitoes as they land on the first collector's legs. * The collections will be conducted both indoors and outdoors from 6 p.m. to 6 a.m. the following morning for 14 consecutive days. * All study volunteers will be trained in proper collection technique and supervised throughout the study by a mobile team led by the study investigators. Volunteers will be monitored for signs of malaria and treated accordingly if they develop symptoms of the disease. * Researchers will collect mosquito samples at the end of the dry season (April-May) and at the start of the rainy season (May-June). * Mosquitoes collected in the study will be analyzed by NIH researchers to learn more about how they survive during the dry season.

Study Details

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