P.vivax presents significant challenges to malaria control and elimination. Research into P. vivax biology and transmission is hindered by the absence of continuous culture methods, resulting in the need of access to fresh P. vivax samples. Papua New Guinea has very high rates of P. vivax transmission and a long history of P. vivax research. In the present study, we describe the establishment of a membrane feeding assay (MFA) to successfully infect Anopheles farauti mosquitoes with malaria parasites. This assay can serve as a platform for future studies to address urgent knowledge gaps surrounding P. vivax transmission.
Anopheles farauti sensu stricto colony mosquitoes were exposed to infected blood collected from n=155 patients with malaria in two clinics within the Madang area. Patients had either P. falciparum (61%) or P. vivax (30%) (mixed (1%), no parasites (8%)) infections by light microscopy. Gametocyte stages were also detected for both species. Up to 400 mosquitoes were exposed to each infected sample. Mosquitoes were dissected for oocysts, 7-9 days post-exposure.
Overall, the proportion of MFAs that gave rise to a mosquito infection was 10.1%. This proportion increased to 32.3 % when only P.vivax infections were considered and to 76.9% when only P. vivax gametocyte positive infections were considered. The correlation trend for oocysts numbers versus P. vivax gametocyte density approached significance (p=0.08). Our results indicate that the mosquito colony can be used to successfully conduct MFAs.
Our membrane feeding assay system can be used to study P. vivax transmission to An. farauti, one of the most widespread and important malaria vectors in the South Pacific. This represents an opportunity to investigate a variety of knowledge gaps relating to P. vivax transmission, in particular the role of naturally acquired immunity on transmission success and the efficacy of antimalarial compounds and vaccine candidates to block transmission.