What drives Plasmodium vivax transmission in incident or relapsing infections (DRIVAX)?

The hypnozoite stage of Plasmodium vivax malaria causes relapsing infections, responsible for a high proportion of clinical and >70% of recurrent infections. Relapses may also be critical for the onward malaria transmission to mosquitoes and undermine malaria elimination efforts. However, the precise contribution of relapses has yet to be quantified.

I hypothesize that the rapid production of P. vivax gametocytes renders many relapsing infections transmissible, but that acquisition of specific immunity will reduce transmission efficiency. My proposal aims to examine the infectivity of relapsing infections compared to incident infections and identify the key host and parasite factors that influence transmission. I will compare the kinetics of parasite and gametocyte densities in the incident and recurrent infections and integrate these data with a detailed assessment of transmissibility to mosquitoes in relation to the transmission-modulating effect of antibody responses to gametocyte antigens. I will deploy advanced genotyping tools to determine the genetic associations between the incident and recurrent infections in humans and subsequent mosquito infections.

My proposal will provide the most comprehensive assessment to date of parasite kinetics and transmissibility in natural P. vivax infections, quantifying the importance of relapse infections to the infectious reservoir and informing malaria control and elimination strategies.