Plasmodium falciparum gametocyte carriage is associated with subsequent plasmodium vivax relapse after treatment

Jessica T. Lin, Delia Bethell, Stuart D. Tyner, Chanthap Lon, Naman K. Shah, David L. Saunders, Sabaithip Sriwichai, Phisit Khemawoot, Worachet Kuntawunggin, Bryan L. Smith, Harald Noedl, Kurt Schaecher, Duong Socheat, Youry Se, Steven R. Meshnick, Mark M. Fukuda

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19 Scopus citations

Abstract

Mixed P. falciparum/P. vivax infections are common in southeast Asia. When patients with P. falciparum malaria are treated and followed for several weeks, a significant proportion will develop P. vivax malaria. In a combined analysis of 243 patients recruited to two malaria treatment trials in western Cambodia, 20/43 (47%) of those with P. falciparum gametocytes on admission developed P. vivax malaria by Day 28 of follow-up. The presence of Pf gametocytes on an initial blood smear was associated with a 3.5-fold greater rate of vivax parasitemia post-treatment (IRR = 3.5, 95% CI 2.0-6.0, p<0.001). The increased rate of post-treatment P. vivax infection persisted when correlates of exposure and immunity such as a history of malaria, male gender, and age were controlled for (IRR = 3.0, 95% CI 1.9-4.7, p<0.001). Polymerase chain reaction (PCR) confirmed that only a low proportion of subjects (5/55 or 9.1%) who developed vivax during follow-up had detectable Pv parasites in the peripheral blood at baseline. Molecular detection of falciparum gametocytes by reverse transcriptase PCR in a subset of patients strengthened the observed association, while PCR detection of Pv parasitemia at follow-up was similar to microscopy results. These findings suggest that the majority of vivax infections arising after treatment of falciparum malaria originate from relapsing liver-stage parasites. In settings such as western Cambodia, the presence of both sexual and asexual forms of P. falciparum on blood smear at presentation with acute falciparum malaria serves as a marker for possible occult P. vivax coinfection and subsequent relapse. These patients may benefit from empiric treatment with an 8-aminoquinolone such as primaquine.

Original languageEnglish
Article numbere18716
JournalPLoS ONE
Volume6
Issue number4
DOIs
StatePublished - 2011
Externally publishedYes

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