Predicting mosquito infection from Plasmodium falciparum gametocyte density and estimating the reservoir of infection
Thomas S Churcher,
Teun Bousema,
Martin Walker,
Chris Drakeley,
Petra Schneider,
André Lin Ouédraogo,
María-Gloria Basáñez
Affiliations
Thomas S Churcher
Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
Teun Bousema
Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
Martin Walker
Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
Chris Drakeley
Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
Petra Schneider
Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
André Lin Ouédraogo
Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
María-Gloria Basáñez
Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
Transmission reduction is a key component of global efforts to control and eliminate malaria; yet, it is unclear how the density of transmission stages (gametocytes) influences infection (proportion of mosquitoes infected). Human to mosquito transmission was assessed using 171 direct mosquito feeding assays conducted in Burkina Faso and Kenya. Plasmodium falciparum infects Anopheles gambiae efficiently at low densities (4% mosquitoes at 1/µl blood), although substantially more (>200/µl) are required to increase infection further. In a site in Burkina Faso, children harbour more gametocytes than adults though the non-linear relationship between gametocyte density and mosquito infection means that (per person) they only contribute slightly more to transmission. This method can be used to determine the reservoir of infection in different endemic settings. Interventions reducing gametocyte density need to be highly effective in order to halt human–mosquito transmission, although their use can be optimised by targeting those contributing the most to transmission.
