The role of the mosquito bite on the dynamics and infectiousness-to-mosquito of asymptomatic Plasmodium falciparum carriers in Ghana
Persistent asymptomatic Plasmodium carriage results in the continuous production of the transmissible sexual stage parasites (gametocytes), which in the presence of competent Anopheles vectors results in the endless spread of malaria. A thorough understanding of the human infectious reservoir and of the gametocyte formation is essential for developing interventions to be targeted to individuals who are most important for the transmission of infection to mosquitoes. The successful completion of the sporogonic life cycle of the parasite within the mosquito sustains malaria transmission. Mosquito saliva is known to generally increase the transmission of pathogens from the mosquito vector to the human host, however little is known about the role played by components of mosquito saliva in the transmission of Plasmodium to humans. We intend to adapt our novel ex vivo gametocyte conversion rate (GCR) assay to determine whether mosquito salivary gland extract directly or indirectly alter GCR and or gametocyte infectiousness to the mosquito. We also intend to use a natural field-based longitudinal study to identify how changes in mosquito biting rates alter gametocyte infectiousness and GCR. We will be following a cohort of adults and children to identify which age range are more at risk of serving as reservoirs for malaria transmission in Ghana as well as identify which season would be ideal to implement transmission blocking interventions
The overall objective is to understand the role played by Anopheles bites in altering GCR, male to female sex ratio and gametocyte infectiousness to the mosquito specifically to:
- To describe the dynamics of asymptomatic asexual and gametocyte stage parasites across off peak and peak transmission seasons
- Assess the effects of varying Anopheles exposure on gametocytogenesis
- Determine the effect of Anopheles saliva on the infectiousness of gametocytes to Anopheles mosquitoes
Ethics approval has been obtained; three community screens have been performed, three mosquito feeding assays have been performed. EIR estimation and in vitro assays are ongoing.