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BackgroundUnderstanding the effect of immunity on Plasmodium falciparum clearance is essential for interpreting therapeutic efficacy studies designed to monitor emergence of artemisinin drug resistance. In low-transmission areas of Southeast Asia, where resistance has emerged, P. falciparum antibodies confound parasite clearance measures. However, variation in naturally acquired antibodies across Asian and sub-Saharan African epidemiological contexts and their impact on parasite clearance re yet to be quantified.MethodsIn an artemisinin therapeutic efficacy study, antibodies to 12 pre-erythrocytic and erythrocytic P. falciparum antigens were measured in 118 children with uncomplicated P. falciparum malaria in the Democratic Republic of Congo (DRC) and compared with responses in patients from Asian sites, described elsewhere.ResultsParasite clearance half-life was shorter in DRC patients (median, 2 hours) compared with most Asian sites (median, 2-7 hours), but P. falciparum antibody levels and seroprevalences were similar. There was no evidence for an association between antibody seropositivity and parasite clearance half-life (mean difference between seronegative and seropositive, -0.14 to +0.40 hour) in DRC patients.ConclusionsIn DRC, where artemisinin remains highly effective, the substantially shorter parasite clearance time compared with Asia was not explained by differences in the P. falciparum antibody responses studied.

Original publication

DOI

10.1093/infdis/jiac232

Type

Journal

The Journal of infectious diseases

Publication Date

08/2022

Volume

226

Pages

324 - 331

Addresses

Burnet Institute, Melbourne, Victoria, Australia.

Keywords

Animals, Humans, Parasites, Plasmodium falciparum, Malaria, Falciparum, Artemisinins, Antimalarials, Antibody Formation, Drug Resistance, Child, Democratic Republic of the Congo