Opisthorchiasis control in northeast Thailand: proposal for a new approach.

Opisthorchiasis, i.e. infection with the liver fluke Opisthorchis viverrini is an important health problem in Thailand and adjacent Laos, and its control is therefore of high priority. Pilot projects have shown that after praziquantel treatment high re-infection rates occurred within a short period of time. To reduce re-infections it is proposed to couple the time of treatment to the seasonal transmission dynamics and thus treat the population in March when risk of infection for the snail and fish intermediate and the human definitive hosts is lowest. Adjustment would save costs and time.