Comparison of three methods for detection of gametocytes in Melanesian children treated for uncomplicated malaria

Stephan Karl, Moses Laman, T. Koleala, C. Ibam, B. Kasian, N. N'Drewei, A. Rosanas-Urgell, Brioni Moore, A. Waltmann, C. Koepfli, P.M. Siba, I. Betuela, Rob Woodward, Tim St Pierre, I. Mueller, Timothy Davis

    Research output: Contribution to journalArticle

    11 Citations (Scopus)

    Abstract

    Background
    Gametocytes are the transmission stages of Plasmodium parasites, the causative agents of malaria. As their density in the human host is typically low, they are often undetected by conventional light microscopy. Furthermore, application of RNA-based molecular detection methods for gametocyte detection remains challenging in remote field settings. In the present study, a detailed comparison of three methods, namely light microscopy, magnetic fractionation and reverse transcriptase polymerase chain reaction for detection of Plasmodium falciparum and Plasmodium vivax gametocytes was conducted.
    Methods
    Peripheral blood samples from 70 children aged 0.5 to five years with uncomplicated malaria who were treated with either artemether-lumefantrine or artemisinin-naphthoquine were collected from two health facilities on the north coast of Papua New Guinea. The samples were taken prior to treatment (day 0) and at pre-specified intervals during follow-up. Gametocytes were measured in each sample by three methods: i) light microscopy (LM), ii) quantitative magnetic fractionation (MF) and, iii) reverse transcriptase PCR (RTPCR). Data were analysed using censored linear regression and Bland and Altman techniques.
    Results
    MF and RTPCR were similarly sensitive and specific, and both were superior to LM. Overall, there were approximately 20% gametocyte-positive samples by LM, whereas gametocyte positivity by MF and RTPCR were both more than two-fold this level. In the subset of samples collected prior to treatment, 29% of children were positive by LM, and 85% were gametocyte positive by MF and RTPCR, respectively.
    Conclusions
    The present study represents the first direct comparison of standard LM, MF and RTPCR for gametocyte detection in field isolates. It provides strong evidence that MF is superior to LM and can be used to detect gametocytaemic patients under field conditions with similar sensitivity and specificity as RTPCR.
    Keywords: Malaria; Gametocyte detection; Magnetic fractionation; Reverse transcriptase PCR; Light microscopy Plasmodium falciparum; Plasmodium vivax; Papua New Guinea
    Original languageEnglish
    Article number319
    Pages (from-to)604-610
    Number of pages8
    JournalMalaria Journal
    Volume13
    DOIs
    Publication statusPublished - 31 Aug 2014

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