High coverage of effective malaria control initiatives – such as the use of treated mosquito nets – in the Greater Mekong Subregion (GMS) has resulted in sharp decreases in malaria in countries where national programmes have achieved high net coverage, and has acted as one of the drivers toward elimination strategies in the region. However, despite the massive reductions over recent years, low level transmission persists even where there is universal coverage of nets or maximal coverage of indoor residual spraying. This remaining, low level transmission has been termed ‘residual malaria transmission’ (RMT).
This project seeks to better understand the magnitude and causes of RMT using multiple approaches, so that appropriate interventions can be put in place to stop it. The first step will be to carry out a review of available data on RMT in the GMS in order to map areas of transmission. Next, field work in Thailand and Vietnam will explore 1) the epidemiology of malaria in RMT communities through blood surveys and risk factor analysis, 2) social and behavioural factors through interviews and discussions, GPS tracking of forest-goers and mobile groups, and observational studies of behaviours and net utilisation; and 3) conduct detailed entomological studies to assess the exact Anopheles composition and entomological parameters including biting times, parity, insecticide resistance status and Plasmodium infection rates.
Through consultations with the World Health Organization Special Programme for Research and Training in Tropical Disease (WHO TDR) and other investigators in African and pan-American regions, the outputs of these activities will not only result in a better understanding of RMT, but also the production of tools and protocols for RMT measurement that can be rolled out to other settings as well as baseline information for development of future research methodologies into the control of RMT.