High prevalence of bancroftian filariasis in Myanmar-migrant workers: a study in Mae Sot district, Tak province, Thailand.

Although the prevalence of lymphatic filariasis in the Thai population is low, migration of Myanmar labor into Thailand may increase the incidence of bancroftian filariasis. Epidemiology of filariasis in Myanmars has not been precisely determined. By using microscopic examination, we found that the microfilarial rate in 654 Myanmar migrants working in Mae Sot, Tak province, was 4.4 per cent. The highest microfilarial rate was found in males aged 21-30 years (6.8%). History of mosquito bites was significantly correlated with microfilaremia. The majority of Myanmar migrants (55.5%) have been staying in Thailand 1-6 years; most (82.0%) have never been back to Myanmar. Seventy-nine per cent of infected Myanmars were from Moulmein (Maulamyine) city. Since these migrants carry the parasite with high infected rate and the mosquito vector Culex quinquefasciatus is also prevalent in Thailand, Thai people are at high risk of acquiring this disease if good control and prevention strategies are not implemented.