Submicroscopic Plasmodium prevalence in relation to malaria incidence in 20 villages in western Cambodia

Malaria Journal

Tripura et al. Malar J (2017) 16:56 DOI 10.1186/s12936-017-1703-5

Open Access

RESEARCH

Submicroscopic Plasmodium prevalence in relation to malaria incidence in 20 villages in western Cambodia Rupam Tripura1,2*†  , Thomas J. Peto1,3†, Christianne C. Veugen2, Chea Nguon4, Chan Davoeung5, Nicola James6, Mehul Dhorda1,7, Richard J. Maude1,3,8, Jureeporn Duanguppama1,9, Krittaya Patumrat1,9, Mallika Imwong1,9, Lorenz von Seidlein1,3, Martin P. Grobusch2, Nicholas J. White1,3 and Arjen M. Dondorp1,3

Abstract  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