A Controlled Human Malaria Infection model for relapsing Plasmodium vivax

A study investigated the safety and feasibility of a Controlled Human Malaria Infection (CHMI) model for relapsing Plasmodium vivax. The aim was to better understand the mechanisms of relapses and provide a platform for future anti-relapse efficacy studies. Five healthy, malaria-naive adults aged 18-45 years with specific genetic and enzymatic profiles were recruited in Oxford, UK. Mosquito-bite CHMI was performed in Nijmegen, The Netherlands, using five Anopheles stephensi mosquitoes infected with the PvW1 strain of P. vivax from Thailand per participant. All participants developed primary P. vivax infection and experienced at least one relapse infection, with two participants experiencing a second relapse. The overall incidence rate of relapse infections was 3.6 per person-year. Adverse events were mild or moderate, and no serious adverse events were recorded, apart from one case of primaquine-induced methaemoglobinaemia which resolved. The study concluded that the CHMI model for relapsing P. vivax is safe and feasible.