Publication: History of malaria treatment as a predictor of subsequent subclinical parasitaemia: a cross‑sectional survey and malaria case records from three villages in Pailin, western Cambodia
Issued Date
2016
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Language
eng
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Mahidol University
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BioMed Central
Bibliographic Citation
Malaria Journal. Vol.15, (2016), 240
Suggested Citation
Peto, Thomas J., Kloprogge, Sabine E., Tripura, Rupam, Chea Nguon, Nou Sanann, Sovann Yok, Chhouen Heng, Cholrawee Promnarate, Jeremy Chalk, Ngak Song, Lee, Sue J., Yoel Lubell, Mallika Imwong, White, Nicholas J., Seidlein, Lorenz von, Arjen Dondorp History of malaria treatment as a predictor of subsequent subclinical parasitaemia: a cross‑sectional survey and malaria case records from three villages in Pailin, western Cambodia. Malaria Journal. Vol.15, (2016), 240. doi:10.1186/s12936-016-1284-8 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/3155
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Title
History of malaria treatment as a predictor of subsequent subclinical parasitaemia: a cross‑sectional survey and malaria case records from three villages in Pailin, western Cambodia
Abstract
Background: Treatment of the sub-clinical reservoir of malaria, which may maintain transmission, could be an
important component of elimination strategies. The reliable detection of asymptomatic infections with low levels of
parasitaemia requires high-volume quantitative polymerase chain reaction (uPCR), which is impractical to conduct on
a large scale. It is unknown to what extent sub-clinical parasitaemias originate from recent or older clinical episodes.
This study explored the association between clinical history of malaria and subsequent sub-clinical parasitaemia.
Methods: In June 2013 a cross-sectional survey was conducted in three villages in Pailin, western Cambodia. Demographic
and epidemiological data and blood samples were collected. Blood was tested for malaria by high-volume
qPCR. Positive samples were analysed by nested PCR to determine the Plasmodium species. To identify previous
episodes of malaria, case records were collected from village malaria workers and local health facilities and linked to
study participants.
Results: Among 1343 participants, 40/122 (32.8 %) with a history of clinical malaria were parasitaemic during the
cross-sectional survey, compared to 172/1221 (14.1 %) without this history (p < 0.001). Among the 212 parasitaemic
participants in the survey, 40 (18.9 %) had a history of clinical malaria, compared to 87 out of 1131 (7.7 %) parasitenegative
participants; p < 0.001, adjusted OR 3.3 (95 % CI; 2.1–5.1). A history of Plasmodium vivax was associated
with sub-clinical P. vivax parasitaemia in the survey (p < 0.001), but this association was not seen with Plasmodium
falciparum (p = 0.253); only three participants had both P. falciparum parasites in the survey and a clinical history of P.
falciparum.
Conclusions: A clinical episode of vivax malaria was associated with subsequent sub-clinical parasitaemia. Treatment
of P. vivax with artemisinin-based combination therapy without primaquine often resulted in recurrent episodes.
Targeting individuals with a history of clinical malaria will be insufficient to eliminate the sub-clinical reservoir as they
constitute a minority of parasitaemias.
