Longitudinal study on Schistosoma japonicum infections in the Philippines. 4. Effect of mass-chemotherapy with praziquantel on incidence at Dagami, Leyte.

ABSTRACT

The effect of selective mass-chemotherapy with praziquantel at a dose of 60 mg/kg a day on the annual incidence of Schistosoma japonicum infection was examined by a follow-up study of 1,800 school children enrolled at 9 primary schools at Dagami Area, Leyte, Philippines. The incidence rates before mass-chemotherapy were 22.2, 24.2, 26.9, 9.6 and 28.4% in a period from school year (SY) 1975/76 to 1979/80, respectively, where the incidence of 9.6% in SY 1978/79 was probably due to extraordinary drought in the previous year. Egg positives including village people were treated and the numbers treated yearly were 22, 943, 273, 300 and 341 from SY 1978/79 to SY 1982/83, respectively. The incidence was reduced drastically as early as one year following the start of mass-chemotherapy, i.e., 8.4, no survey, 6.8 and 15.4%, from SY 1980/81 to SY 1983/84, respectively, and which demonstrated the efficacy of mass-chemotherapy on reduction of transmission.