Observational studies on the human malaria infectious reservoir in The Gambia
Accumulating evidence suggests that asymptomatic carriers contribute to the bulk of malaria transmission in Sub-Saharan Africa. In low transmission settings, much of the asymptomatic reservoir – people carrying the disease without showing symptoms - is submicroscopic, thus invisible to commonly used rapid tests. A better understanding of human-to-mosquito transmission from these low-density infections can inform strategies for interrupting transmission.
In this talk, we will present findings from a trial that aimed to reduce the infectious reservoir in villages of low endemicity in The Gambia. Malaria case management was implemented in eight villages that were subsequently randomised to receive either no additional interventions, weekly fever screening, mass drug administration (MDA) or mass screening and treatment (MSAT).
Molecular determination of parasite and gametocyte carriage and direct assessments of transmission to locally reared mosquito, A. coluzzii, allowed prospective assessment of the infectious reservoir. Preliminary findings indicate that both MSAT and MDA reduced the incidence of new infections. While all intervention arms observed reduced parasite carriage at the end of the season, MDA resulted in the largest impact on the human infectious reservoir during the transmission season. Interestingly, even in this low-endemic area, mosquito infections primarily occurred from asymptomatic infections.
Harouna Dit Massire Soumare, MRC Unit The Gambia at LSHTM
Harouna Dit Massire Soumare is a research investigator specializing in entomology and parasitology. He trained at the Malaria Research & Training Center at the University of Sciences Techniques and Technologies in Bamako, Mali. He has participated in several trials that evaluated the blockade of malaria transmission from mosquito to humans using gametocytocidal drugs, such as primaquine and methylene blue in addition to antimalarial drugs treatments. He currently works at the Medical Research Council Unit The Gambia and he has been leading the entomological component in two trials that investigate the effect of mass drug administration of ivermectin against malaria and assess the infectiousness of natural gametocyte carriers to mosquitoes.
Bakary Conteh, MRC Unit The Gambia at LSHTM
Bakary Conteh, MD, Research Clinician and Study Coordinator at the Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine (MRCG@LSHTM). Bakary leads clinical research teams, helping to set up study sites and follow up study participants in multiple cohort studies and clinical trials conducted at MRCG@LSHTM involving paediatric patients and adult populations. Recently he played a leading role in two randomized controlled trials investigating the efficacy, safety and tolerability of pyronaridine-artesunate in asymptomatic malaria-infected individuals and the effect of mass drug administration of ivermectin and dihydroartemisinin piperaquine against malaria in settings with high coverage of standard control interventions.
Marta Moreno, LSHTM
Marta Moreno is an assistant professor in the Department of Infection Biology at the London School of Hygiene & Tropical Medicine. She has carried out extensive research on both vector biology and malaria transmission dynamics in the Peruvian Amazon, with emphasis on behaviour of malaria vectors after the implementation of different malaria control strategies. Since 2018, she has been investigating the contribution of asymptomatic Plasmodium falciparum infections to the infectious reservoir in The Gambia. The goal of this research is to assess different diagnostic approaches for detecting symptomatic and asymptomatic infections earlier and their impact on parasite carriage.