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London School of Hygiene & Tropical Medicine Malaria Centre

Malaria research in parasite biology

Longitudinal immune responses to Plasmodium falciparum gametocytes in Ghanaian school children.

LSHTM investigators:
Bismarck Dinko, Maha Saeed, Teun Bousema & Colin Sutherland.
External collaborators:
Harry Tagbor & John Larbi (Kwame Nkrumah University of Science and Technology, Ghana).
Funding body:
Ghana Education Trust Fund.

Malaria transmission-reducing interventions are key components of malaria control and elimination.

However, little is known about the immune responses directed at circulating Plasmodium falciparum gametocytes in humans. We set out to determine patterns in gametocyte surface antigen (GSA) antibody prevalence and seek stronger evidence for specific immune suppression of gametocytes. Flow cytometry is being used to detect antibodies recognising cultured 3D7a mature gametocyte-infected erythrocyte surface in plasma  from asymptomatic malaria parasite positive children from a rainforest region in Ghana. These children were treated with dihydro-artemisinin piperaquine, and plasma collected weekly for 1 month. By microscopy, 8.9% (15/168) of the children enrolled carried gametocyte at enrolment and 20% of them developed gametocytes during subsequent follow-up. More than 50% of the gametocyte-positive children tested to date carry antibodies to GSA. Further longitudinal flow cytometry will enable understanding of the dynamics of GSA development following treatment of asymptomatic malaria.