5-YEAR IMPACT OF CHEMOTHERAPY ON MORBIDITY ATTRIBUTABLE TO SCHISTOSOMA-JAPONICUM INFECTION IN THE DONGTING LAKE REGION

OBJECTIVE TO determine changes in the last 5 years of the fraction of acute and chronic symptoms attributable to schistosomiasis japonica in fishing communities with moderate endemicity in the Dongting Lake reg ion of China. METHOD Complete medical histories, physical examinations , and stool samples were obtained from 1909 individuals (53% male) ran ging in age from 4 to 81 years. Age, sex, occupation, frequency of wat er contact, number of times treated for schistosomiasis, and last year of treatment were tested as potential effect modifiers and confounder s. RESULTS Overall, there were very few infected cases and very little variation in any prevalence ratio with infection intensity, sex, age, year of last treatment, number of times treated or frequency of water contact. The attributable fraction of liver enlargement in one pillag e was estimated at 0.114 (11.4%), although this was not significantly > 0 (95% CI; - 0.008-0.237). CONCLUSION The chemotherapy-based schisto somiasis control programme in this locality has succeeded in reducing attributable morbidity to undetectable levels, but many uncertainties remain about sustaining control efforts in the future. Both old and ne w control strategies will have to be examined if the health and well-b eing of these people are to be maintained into the next millennium, gi ven that periodic chemotherapy will not be accepted indefinitely.