Successful sporozoite challenge model in human volunteers with plasmodium vivax strain derived from human donors.
Herrera, Sócrates | 2019-10-11
Successful establishment of a Plasmodium vivax sporozoite challenge model in humans isdescribed. Eighteen healthy adult, malaria-naïve volunteers were randomly allocated to Groups A–C and exposed to 3 ± 1, 6 ± 1, and 9 ± 1 bites of Anopheles albimanus mosquitoes infected with P.vivax, respectively. Seventeen volunteers developed signs and symptoms consistent with malaria,and geometric mean prepatent periods of 11.1 days (9.3–11) for Group A; 10.8 days (9.8–11.9) forGroup B; and 10.6 days (8.7–12.4) for Group C, with no statistically significant difference amonggroups (Kruskal-Wallis, P = 0.70). One volunteer exposed to eight mosquito bites did not developa parasitemia. No differences in parasite density were observed and all individuals successfullyrecovered after anti-malarial treatment. None of the volunteers developed parasite relapses withinan 18-month follow-up. In conclusion, malaria-naive volunteers can be safely and reproducibly infected with bites of 2–10 An. albimanus mosquitoes carrying P. vivax sporozoites. Thischallenge method is suitable for vaccine and anti-malarial drug testing.