Naturally acquired immunity among Kenyan adults suppresses the West African P. falciparum NF54 strain in controlled human malaria infection (CHMI)
Kapulu MC., Njuguna P., Hamaluba M., Kimani D., Ngoi JM., Musembi J., Ngoto O., Otieno E., Billingsley PF.
<jats:title>Abstract</jats:title><jats:p>We used controlled human malaria infection (CHMI) to study naturally acquired immunity of Kenyan adults. We administered 3.2×10<jats:sup>3</jats:sup> cryopreserved <jats:italic>Plasmodium falciparum</jats:italic> sporozoites (SPZ, NF54 West African strain) and undertook clinical monitoring and serial quantitative PCR (qPCR). Of the 142 volunteers who were eligible for analysis: 26 (18.3%) had febrile symptoms and were treated; 30 (21.1%) reached ≥500 parasites/μl and were treated; 53 (37.3%) had parasitaemia without meeting thresholds for treatment and; 33 (23.2%) remained qPCR negative. We find that the immunity acquired by some Kenyan adults can completely suppress <jats:italic>in vivo</jats:italic> growth of a parasite strain originating from outside Kenya.</jats:p>