Molecular screening of Plasmodium infections among migrant workers in Thailand

Background & objective: A cross-sectional study was conducted to determine the prevalence of Plasmodium infections among migrant workers in Thailand. Methods: A total of 241 migrants at Kanchanaburi, Pathumthani and Nakornpathom provinces of Thailand were recruited in our surveillance. Blood samples were examined for human malaria parasites by using microscopy and semi-nested multiplex PCR (SnM-PCR). Results: Laboratory diagnosis revealed 6.2% total positive rate. As compared to microscopy (26.7%), SnM-PCR was more sensitive (93.3%) for malaria. Plasmodium falciparum was predominant than P. vivax (53%: 40%, respectively). The majority of positive cases were from Myanmar workers who had low parasitaemia and without symptoms. The highest prevalence (13.7%) was found among migrant workers from Kanchanaburi province in western Thailand. Conclusion: These findings indicate risk of malaria transmission from migrant workers. Malaria surveillance should be included in the health-screening program for migrants in Thailand to manage this health risk.