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Clin Infect Dis. 2019 Apr 19. pii: ciz131. doi: 10.1093/cid/ciz131. [Epub ahead of print]

Prospective Clinical and Molecular Evaluation of Potential Plasmodium ovale curtisi and wallikeri Relapses in a High-transmission Setting.

Author information

1
Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine and I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Germany.
2
Centre de Recherches Médicales de Lambaréné, Gabon.
3
Institut für Tropenmedizin, Universität Tübingen, Germany.
4
Center for Medical Statistics, Informatics, and Intelligent Systems, Section for Medical Statistics, Medical University of Vienna, Austria.
5
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom.
6
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
7
German Center for Infection Research (DZIF), partner site Tübingen, Germany.
8
Institute of Parasitology, University of Veterinary Medicine Vienna, Austria.
9
German Center for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel, Hamburg, Germany.

Abstract

BACKGROUND:

Plasmodium ovale curtisi and wallikeri are perceived as relapsing malarial parasites. Contrary to Plasmodium vivax, direct evidence for this hypothesis is scarce. The aim of this prospective study was to characterize the reappearance patterns of ovale parasites.

METHODS:

P. ovale spp. infected patients were treated with artemether-lumefantrine and followed biweekly for up to 1 year for the detection of reappearing parasitemia. Molecular analysis of reappearing isolates was performed to identify homologous isolates by genotyping and to define cases of relapse following predefined criteria.

RESULTS:

At inclusion, 26 participants were positive for P. ovale curtisi and/or P. ovale wallikeri. The median duration of follow-up was 35 weeks. Reappearance of the same P. ovale species was observed in 46% of participants; 61% of P. ovale curtisi and 19% of P. ovale wallikeri infection-free intervals were estimated to end with reappearance by week 32. Based on the predefined criteria, 23% of participants were identified with 1 or 2 relapses, all induced by P. ovale curtisi.

CONCLUSION:

These findings are in line with the currently accepted relapse theory inasmuch as the reappearance of P. ovale curtisi strains following initial blood clearance was conclusively demonstrated. Interestingly, no relapse of P. ovale wallikeri was observed.

KEYWORDS:

Plasmodium ovale ; Plasmodium ovale curtisi ; Plasmodium ovale wallikeri ; CERMEL; relapse

PMID:
31066448
DOI:
10.1093/cid/ciz131

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