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EBioMedicine. 2017 Nov;25:66-72. doi: 10.1016/j.ebiom.2017.10.003. Epub 2017 Oct 4.

Detection of Malaria Parasites After Treatment in Travelers: A 12-months Longitudinal Study and Statistical Modelling Analysis.

Author information

1
Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden. Electronic address: manijeh.vafa-homann@ki.se.
2
Department of Molecular Bioscience, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
3
Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
4
Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
5
Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
6
Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
7
Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.

Abstract

The rapid clearance of malaria parasite DNA from circulation has widely been accepted as a fact without being systemically investigated. We assessed the persistence of parasite DNA in travelers treated for Plasmodium falciparum malaria in a malaria-free area. Venous blood was collected at the time of admission and prospectively up to one year. DNA and RNA were extracted and analyzed using species-specific and gametocyte-specific real-time PCR as well as merozoite surface protein 2 (msp2)-PCR. In 31 successfully treated individuals, asexual parasites were seen by microscopy until two days after treatment, whereas parasite DNA was detected by msp2- and species-specific PCR up to days 31 and 42, respectively. Statistical modelling predicted 26% (±0·05 SE) species-specific PCR positivity until day 40 and estimated 48days for all samples to become PCR negative. Gametocytes were detected by microscopy and PCR latest two days after treatment. CT values correlated well with microscopy-defined parasite densities before but not after treatment started. These results reveal that PCR positivity can persist several weeks after treatment without evidence of viable sexual or asexual parasites, indicating that PCR may overestimate parasite prevalence after treatment.

KEYWORDS:

Gametocyte; Malaria; Real-time PCR; Traveler; Treatment; msp2-PCR

PMID:
29050948
PMCID:
PMC5704054
DOI:
10.1016/j.ebiom.2017.10.003
[Indexed for MEDLINE]
Free PMC Article

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