Epidemiology and population genetics of malaria parasites in Kenya

Scale-up of vector interventions, improved diagnosis, and effective treatment have collectively contributed to significant global reductions in malaria mortality and morbidity over the last 15 years. Nevertheless, malaria burden remains high in sub-Saharan Africa, which reported 215 million cases and 380,000 deaths in 2019. Malaria burden reduction is not uniform, with some countries or regions continuously exhibiting high incidence whereas others show drastic reductions. Consequently, many African countries have proposed sub-national stratification of malaria risk and have developed corresponding surveillance and intervention plans to target heterogeneous malaria burden. As the prevalence of clinical malaria cases decreases, transmission becomes more focal and the proportion of malaria infections that are asymptomatic increases. Asymptomatic cases typically go undetected and untreated. They constitute an obscure parasite reservoir, silently sustaining transmission and threatening malaria control and elimination efforts. Functional and responsive malaria surveillance systems are necessary for quantifying the true burden of disease, identifying residual transmission foci for targeted control, and evaluating the effectiveness of interventions. Enhanced surveillance methods and more sensitive malaria diagnostic methods are needed to detect symptomatic and asymptomatic infections in low-transmission settings.

The project will examine the effectiveness of hospital-based clinical malaria cases and reactive case detection methods in transmission hotspot detection (Aim 1), and investigate the genetic connectivity and diversity of malaria infections within and among clusters of malaria cases using amplicon deep sequencing and microsatellite typing (Aim 2). Identification of transmission hotspots will inform malaria intervention strategies best suited to local epidemiological contexts. Patterns of genetic connectivity among parasite isolates will reveal the geographical spread and transmission network of malaria infections. These data will improve the understanding of malaria epidemiology in settings where transmission is rapidly declining, thus guiding decision-makers in tailoring optimal strategies to achieve local malaria control and elimination goals. This proposed research will have broad implications for malaria surveillance in other areas of Africa that are experiencing significant reductions in malaria transmission. 

Project details

Asymptomatic Reservoir
Epidemiology
Measurement of Transmission
Surveillance

May 2022 — Apr 2025

$42,223

Kenya

Malaria Molecular Surveillance (MMS)