Journal Article

Novel Cross-Border Approaches to Optimise Identification of Asymptomatic and Artemisinin-Resistant Plasmodium Infection in Mobile Populations Crossing Cambodian Borders

Canavati, Sara E., Canier, Lydie, Edwards, Hannah M., Rang, Chandary, Roca-Feltrer, Arantxa, Menard, Didier, Khim, Nimol, Ly, Po, Sovannaroth, Siv, Ashton, Ruth A., Meek, Sylvia R.

2015

Overview

Human population movement across country borders presents a real challenge for malaria control and elimination efforts in Cambodia and its neighbouring countries. To quantify Plasmodium infection among the border-crossing population, including asymptomatic and artemisinin resistant (AR) parasites, three official border crossing points, one from each of Cambodia's borders with Thailand, Laos and Vietnam, were selected for sampling. A total of 3206 participants (of 4110 approached) were recruited as they crossed the border, tested for malaria and interviewed. By real-time polymerase chain reaction (RT-PCR), 5.4% of all screened individuals were found to harbour Plasmodium parasites. The proportion was highest at the Laos border (11.5%). Overall there were 97 P. vivax (55.7%), 55 P. falciparum (31.6%), two P. malariae (1.1%) and 20 mixed infections (11.5%). Of identified infections, only 20% were febrile at the time of screening. Of the 24 P. falciparum samples where a further PCR was possible to assess AR, 15 (62.5%) had mutations in the K13 propeller domain gene, all from participants at the Laos border point. Malaria rapid diagnostic test (RDT) pLDH/HRP-2 identified a positivity rate of 3.2% overall and sensitivity compared to RT-PCR was very low (43.1%). Main individual risk factors for infection included sex, fever, being a forest-goer, poor knowledge of malaria prevention methods and previous malaria infection. Occupation, day of the week and time of crossing (morning vs. afternoon) also appeared to play an important role in predicting positive cases. This study offers a novel approach to identify asymptomatic infections and monitor AR parasite flow among mobile and migrant populations crossing the borders. Similar screening activities are recommended to identify other hot borders and characterise potential hot spots of AR. Targeted \"customised\" interventions and surveillance activities should be implemented in these sites to accelerate elimination efforts in the region.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adolescent / Adult / Antimalarials / Antimalarials - pharmacology / Antimalarials - therapeutic use / Artemisinin / Artemisinins / Artemisinins - pharmacology / Artemisinins - therapeutic use / Asymptomatic Infections / Asymptomatic Infections - epidemiology / Border security / Borders / Cambodia / Cambodia - epidemiology / Carrier State / Carrier State - diagnosis / Carrier State - drug therapy / Carrier State - epidemiology / Consent / Consortia / Diagnostic systems / Diagnostic tests / Distribution / Drug Resistance / Emigration and Immigration / Epidemiology / Female / Fever / Health aspects / Human health and pathology / Human motion / Human populations / Humans / Infections / Infectious diseases / Laos / Laos - epidemiology / Life Sciences / Malaria / Malaria - diagnosis / Malaria - drug therapy / Malaria - epidemiology / Male / Mutation / Number systems / Parasites / Parasitology / Plasmodium / Plasmodium - genetics / Plasmodium - isolation & purification / Plasmodium falciparum / Plasmodium falciparum - drug effects / Plasmodium falciparum - genetics / Plasmodium falciparum - isolation & purification / Plasmodium malariae / Plasmodium malariae - drug effects / Plasmodium malariae - genetics / Plasmodium malariae - isolation & purification / Plasmodium vivax / Plasmodium vivax - drug effects / Plasmodium vivax - genetics / Plasmodium vivax - isolation & purification / Polymerase chain reaction / Population / Populations / Product testing / Risk analysis / Risk Factors / Sampling methods / Screening / Studies / Surveillance / Systematic review / Thailand / Thailand - epidemiology / Transients and Migrants / Tropical diseases / Vector-borne diseases / Vietnam / Vietnam - epidemiology / Young Adult