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Please use this identifier to cite or link to this item: http://repository.li.mahidol.ac.th/dspace/handle/123456789/42852
Title: Submicroscopic Plasmodium prevalence in relation to malaria incidence in 20 villages in western Cambodia
Authors: Rupam Tripura
Thomas J. Peto
Christianne C. Veugen
Chea Nguon
Chan Davoeung
Nicola James
Mehul Dhorda
Richard J. Maude
Jureeporn Duanguppama
Krittaya Patumrat
Mallika Imwong
Lorenz Von Seidlein
Martin P. Grobusch
Nicholas J. White
Arjen M. Dondorp
Mahidol University
Academic Medical Centre, University of Amsterdam
Nuffield Department of Clinical Medicine
National Center for Parasitology, Entomology and Malaria Control
Provincial Health Department
London School of Hygiene & Tropical Medicine
Harvard School of Public Health
Keywords: Immunology and Microbiology
Issue Date: 31-Jan-2017
Citation: Malaria Journal. Vol.16, No.1 (2017), 1-12
Abstract: © 2017 The Author(s). Background: Cambodia has seen a marked reduction in the incidence of Plasmodium falciparum over the past decade without a corresponding decline in Plasmodium vivax incidence. It is unknown to what extent local transmission is sustained by a chain of clinical and sub-clinical infections or by continued re-introduction via migration. Using an ultrasensitive molecular technique, 20 villages in western Cambodia were surveyed to detect the low season prevalence of P. falciparum and P. vivax and local treatment records were reviewed. Methods: During March to May 2015 cross-sectional surveys were conducted in 20 villages in Battambang, western Cambodia. Demographic and epidemiological data and venous blood samples were collected from 50 randomly selected adult volunteers in each village. Blood was tested for Plasmodium infections by rapid diagnostic test (RDT), microscopy and high volume (0.5 ml packed red blood cell) quantitative polymerase chain reaction (uPCR). Positive samples were analysed by nested PCR to determine the Plasmodium species. Malaria case records were collected from the Provincial Health Department and village malaria workers to determine incidence and migration status. Results: Among the 1000 participants, 91 (9.1%) were positive for any Plasmodium infection by uPCR, seven (0.7%) by microscopy, and two (0.2%) by RDT. uPCR P. vivax prevalence was 6.6%, P. falciparum 0.7%, and undetermined Plasmodium species 1.8%. Being male (adjusted OR 2.0; 95% CI 1.2-3.4); being a young adult <30 years (aOR 2.1; 95% CI 1.3-3.4); recent forest travel (aOR 2.8; 95% CI 1.6-4.8); and, a history of malaria (aOR 5.2; 95% CI 2.5-10.7) were independent risk factors for parasitaemia. Of the clinical malaria cases diagnosed by village malaria workers, 43.9% (297/634) and 38.4% (201/523) were among migrants in 2013 and in 2014, respectively. Plasmodium vivax prevalence determined by uPCR significantly correlated with vivax malaria incidences in both 2014 and 2015 (p = 0.001 and 0.002, respectively), whereas no relationship was observed in falciparum malaria (p = 0.36 and p = 0.59, respectively). Discussion: There was heterogeneity in the malaria parasite reservoir between villages, and Plasmodium prevalence correlated with subsequent malaria incidence. The association was attributable chiefly to P. vivax infections, which were nine-fold more prevalent than P. falciparum infections. In the absence of a radical cure with 8-aminoquinolines, P. vivax transmission will continue even as P. falciparum prevalence declines. Migration was associated with over a third of incident cases of clinical malaria. Trial registration clinicaltrials.gov (NCT01872702). Registered 4 June 2013.
URI: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85011356014&origin=inward
http://repository.li.mahidol.ac.th/dspace/handle/123456789/42852
ISSN: 14752875
Appears in Collections:Scopus 2016-2017

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