Identifying residual foci of malaria infection in a context of decreasing transmission

The spectrum of malaria is a continuum from asymptomatic infection to clinical disease. Asymptomatic carriage (AC) is an acknowledged public health challenge due to its role in maintaining transmission. Its prevalence and correlation to the burden of disease are however difficult to clearly define. As malaria transmission declines, the prevalence of disease becomes more heterogeneous with an increasing tendency for spatial clustering. Within this context, AC of malaria infection will become increasingly important as interrupting transmission requires targeting the carriers. However, it is unclear what the best approach to identify them is, particularly when they represent a small proportion of the human population and malaria transmission has become extremely heterogeneous. We propose to evaluate a case-contact approach for the identification of residual foci of transmission. The risk of malaria infection in residents of the same household of clinical cases identified in health facilities will be compared with controls selected in contiguous households. Risk factors for malaria infection will also be determined, including distance from breeding sites and the house structure.