Division of Geographic Medicine, Department of Medicine, The Miriam Hospital and International Health Institute, Department of Parasitology, Nanjing Medical College, Institute of Parasitic Diseases, Research Institute of Tropical Medicine, Providence, Rhode Island, People's Republic of China
The impact of annual screening and treatment with praziquantel on schistosomiasis japonica was examined on Jishan Island in PoYang Lake, Jiangxi Province, China. Prevalence of infection in the community decreased from 39% in year 1 to 33% in year 3 with a corresponding decrease in the geometric mean egg count from 51 eggs per gram of stool (epg) to 31 epg. The most dramatic changes in infection status and intensity of infection were observed in younger individuals (0–19 years of age). The prevalence of hepatosplenomegaly also significantly decreased, again primarily in younger individuals. No change in the community prevalence of schistosome-induced hepatic fibrosis was observed as determined by ultrasonography. Longitudinal cohort analysis, however, demonstrated significant improvement in treated individuals with advanced hepatic fibrosis. These data indicate that annual screening and treatment had a significant impact on infection status and morbidity and suggest that community therapy may be an effective approach to control schistosomiasis japonica in lake regions and marshlands in China. Further studies are necessary to determine the optimal and most cost-effective approach for drug delivery.