Community control studies on Strongyloides infection in a model island of Okinawa, Japan

The community control program for Strongyloides infection was conducted by fecal examination and subsequent treatment of the population on a model island (Kume Island) in Okinawa, Japan, for 5 years from 1993 to 1997. More than 1,200 persons, accounting for 17% to 20% of the persons subjected, received fecal examinations each year. The positive rate in 1993 was found to be 9.7% (133/1,374). The positive rate decreased to 6.5% (95/1,468) in 1994, then 4.8% (60/1,245) in 1995, 2.2% (27/1,225) in 1996 and 2.7% (33/1,217) in 1997 through treatment with albendazole or ivermectin on the positive persons detected each year. Among the positive persons detected after operation of the control program, more than 70% were newly detected persons who did not receive an examination in the previous year or were falsely-negative in the previous examination. The low enforcement of procuring fecal examinations, as well as low sensitivity of fecal examination, might have had an effect on the relatively gradual decrease in the prevalence rate, in spite of the high efficacy of the treatment. The results indicate that continuation of the control program for several years is needed to effectively reduce the prevalence of the parasitic infection in the community.