SCHISTOSOMIASIS-JAPONICA IN THE PHILIPPINES - THE LONG-TERM IMPACT OFPOPULATION-BASED CHEMOTHERAPY ON INFECTION, TRANSMISSION, AND MORBIDITY

The long-term impact of annual case-finding and chemotherapy with praz iquantel on schistosomiasis japonica was examined in an 8-year longitu dinal study in the Philippines. The prevalence, incidence, and intensi ty of infection and schistosome-induced hepatomegaly significantly dec reased within 3-4 years of treatment and then stabilized despite conti nual population-based chemotherapy. Hepatomegaly rapidly developed in acutely infected persons, with 82% of subjects developing hepatic enla rgement within 2 years of reinfection. These data suggest that abrupt discontinuation of current control measures in the Philippines may res ult in a rapid rebound in morbidity. Age-dependent acquired resistance to reinfection also developed in subjects chronically exposed to schi stosomiasis japonica, suggesting that a vaccine may represent an alter native approach for control of this parasitic infection.