Study of Controlled Human Plasmodium Vivax Infection

This is a sporozoite-challenge clinical study with the primary aim of assessing the safety and feasibility of controlled human P. vivax malaria infection in two healthy volunteers. The investigators will also assess the growth of and the immune response to P. vivax infection, and assess the induction of sexual gametocytaemia post-CHMI via the natural route of malaria infection (mosquito bite). A secondary objective is to develop a blood inoculum of P. vivax-infected blood for future testing of candidate vaccines.

This is a sporozoite-challenge clinical study with the primary aim of assessing the safety and feasibility of controlled human P. vivax malaria infection in two healthy volunteers. The investigators will also assess the growth of and the immune response to P. vivax infection, and assess the induction of sexual gametocytaemia post-CHMI via the natural route of malaria infection (mosquito bite). A secondary objective is to develop a blood inoculum of P. vivax-infected blood for future testing of candidate vaccines. Two healthy, malaria-naïve adults aged between 18 and 50 years will be recruited at the CCVTM, Oxford. CHMI by sporozoites will be delivered by mosquito bite at Imperial College, London, and follow-up during the post-challenge period will be at the CCVTM in Oxford. The two volunteers will have blood taken at regular intervals post-CHMI to assess the immune response to primary P. vivax infection, and also the gametocytaemia following P. vivax infection, and the volunteers will be monitored closely until the volunteers meet the criteria for treatment. Up to 250 mL (half a unit) of blood will be taken just prior to treatment from the two successfully infected volunteers (as determined by measurement of the parasitaemia) and frozen down for future use in blood-stage CHMI trials. The volunteers will be treated with a standard 60-hour course of oral artemether-lumefantrine (Riamet) followed by a 2-week course of partially-observed oral Primaquine for radical cure of P. vivax hypnozoites. The volunteers will be followed up for 3 months in the clinic and email follow-up will continue out to 5 years to monitor for clinical relapse.