A strategy for emergency treatment of Schistosoma japonicum-infested water

Abstract. background: schistosomiasis japonica,caused by contact with schistosoma japonicum cercaria-infested water when washing,bathing or production,remains a major public-health concern in china. the purpose of the present study was to investigate the effect of a suspension concentrate of niclosamide (scn) on killing cercaria of s. japonicum that float on the water surface,and its toxicity to fish,so as to establish an emergency-treatment intervention for rapidly killing cercaria and eliminating water infectivity. results: at 30 min after spraying 100 mg/l scn,with niclosamide dosages of 0.01,0.02,0.03,0.04 g/m2,the water infectivity reduced significantly and no infectivity was found at 60 min after spraying scn. the surface of static water was sprayed with 100 mg/l scn,the peak concentration was found at 0 min,and the solution diffused to site with a water depth of 10 cm after 10 min. 30 min later,scn diffused to the whole water body,and distributed evenly. after spraying 100 mg/l scn onto the surface of the water with a volume of(3.14 × 202×50)cm3,with niclosamide dosages of 0.02 g/m2,96 h later,no death of zebra fish was observed. conclusions: by spraying 100 mg/l scn,with a niclosamide dosage of 0.02 g/m2 onto the surface of s. japonicum-infested water,infectivity of the water can be eliminated after 30-60 min,and there is no evident toxicity to fish. this cercaria-killing method,as an emergency-treatment intervention for infested water,can be applied in those forecasting and early warning systems for schistosomiasis. © 2011liang et al; licensee biomed central ltd.