Malaria Vector ecology and transmission

Summary The project goal is to investigate the urban-rural continuum of malaria transmission in relation to vector ecology in urban, peri-urban, and surrounding rural areas of Bamako, Mali. Steps to mount effective malaria elimination programs in African countries are confounded by the resilience of the major vector species in the Anopheles gambiae complex. There are the well-known obstacles due to insecticide resistance and shifts in vector behavior to outdoor residual transmission. However, the challenge of elimination is even more complex and may not be solved even with the addition of new vector control tools. This project, which will be conducted in Mali, builds on data from 15 years of continuous NIH ICEMR support. During this period, there has been a decline in both human and vector transmission indicators following the scale up of core malaria control interventions. These interventions have been primarily implemented in rural settings because of the high malaria endemicity. In contrast, in urban settings of Bamako, there is a low prevalence of Plasmodium falciparum malaria (1-3%), and health facilities report malaria cases diagnosed year-long with a high proportion of severe malaria. This renewal application expends the vector ecology research capacity built in the ICEMR to address key issues related to malaria transmission in urban Bamako and its surrounding areas. Specific Aims include: 1) Determine the contribution of endogenous and exogenous sources of malaria mosquitoes in urban settings; 2) Determine spatial/ temporal concentrations and survival of malaria mosquitoes in urban, semiurban, and surrounding rural areas; 3) Assess insecticide resistance of Anopheline mosquito vectors in different ecological settings, in association with selection pressure regimes and potential impact on malaria transmission. This approach will generate new findings of high public health importance considering accelerating socio-economic and environmental changes in West African cities. Research will detail how future shifts in the species composition of primary and secondary local vector populations will change, especially with the imminent arrival of the invasive Anopheles stephensi. Overall, this project takes a holistic approach to reveal new aspects of vector ecology that impact the complexity and changing epidemiology of malaria parasite transmission in West Africa.