AN EXAMINATION OF CURRENT CONTROL STRATEGIES FOR ASIAN SCHISTOSOMIASIS IN THE DONGTING LAKE REGION OF CHINA .2. A 5-YEAR FOLLOW-UP SURVEY ON QINGSHAN ISLAND

In 1995-1996 we conducted an epidemiological survey in two communities (1656 individuals) on Qingshan island, Hunan province P.R. China, in order to determine the efficacy of current control strategies since th eir upgrading in 1991. In 1996, the overall prevalence for Schistosoma japonicum, Ascaris lumbricoides, Ancylostoma duodenale, and Trichuris trichiura had decreased moderately since 1991. The age-specific preva lence for S. japonicum for each of the representative age groups decre ased slightly, but there was a significant reduction in these prevalen ces for the 5-9 (P<0.01), 55-59 (P<0.05) and the over 60 (P<0.01) age groups. The 1996 intensities of infection for schistosomiasis were hig her for all the age categories except for those aged 0-4 and 25-29 yea rs of age. When the study population was further classified according to the percent uninfected, lightly infected (8-100 eggs/g (epg)), mode rately infected (101-400 epg) and heavily infected (>400 epg) for S. j aponicum, there were fewer (5.6%) people infected in 1996 but the prop ortions of moderately (21.3 vs. 15.5%) and heavily (7.6 vs. 2.3%) infe cted individuals were higher than those observed in 1991. The reported cases of weakness and hepatomegaly (MSL greater than or equal to 3) w ere significantly lower (P<0.01) in 1996 for both uninfected and infec ted (all intensities) individuals. General episodes of diarrhoea were also significantly lower in 1996 for those lightly (P<0.05) and heavil y (P<0.01) infected. Likewise, the occurrence of splenomegaly (Hackett 's greater than or equal to 2) was significantly lower among uninfecte d (P<0.01) and heavily infected (P<0.05) patients. In summary, althoug h significant progress has been made in controlling schistosomiasis an d other helminth infections in this highly endemic focus for schistoso miasis, there is still room for improvement. Chemotherapy for bovines and humans, mollusciding for Oncomelania control and health education should be initiated and upgraded if the health and well being of these island communities is to further improve. (C) 1997 Elsevier Science B .V.