title: [Surveillance and forecast system of schistosomiasis in Jiangsu Province. IV. Establishment of Schistosoma japonicum cercaria-killing method by spraying niclosamide suspension on water surface].
abstract: OBJECTIVE
  To investigate the effect of suspension concentrate of niclosamide (SCN) on killing cercariae of Schistosoma japonicum on water surface, optimization and impact on fish, so as to establish an emergency-treatment intervention for rapidly killing cercariae and eliminating water infectivity.
  
  
  METHODS
  SCN was formulated into different concentrations of solutions, and then the solutions were sprayed on the surface of water containing S. japonicum cercariae. The water infectivity was determined by using mice at 0, 10, 30 min after spraying SCN. SCN was formulated into a solution of 100 mg/L and then sprayed on the surface of the water by using the spraying values of 0.01, 0.02, 0.03 g/m2 and 0.04 g/m2. At 30 min and 60 min after spraying, the water infectivity was determined by using mice. Zebra fish were transferred into the static water, then 100 mg/L SCN (s), using spraying values of 0.01, 0.02, 0.03 g/m2 and 0.04 g/m2, were sprayed on water surface. At 0, 10, 30, 60 min after spraying, the samples were collected at water depths of 0, 10, 20, 30, 40 cm, and niclosamide was determined by using high-performance liquid chromatography. The death of zebra fish was continually observed within 96 h after spraying SCN.
  
  
  RESULTS
  At 0, 10, 30 min after spraying 1 000, 100, 10, 1, 0.1 mg/L SCN on water surface, the infectivity of water significantly decreased. At 30 min after spraying 1 000 mg/L and 100 mg/L SCN, no schistosome infectivity was detected in the water. At 30 min after spraying 100 mg/L SCN, with spraying values of 0.01, 0.02, 0.03, 0.04 g/m2, the water infectivity significantly reduced, and no infectivity was found 60 min after spraying SCN. After 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, and 30 min later, SCN diffused to the whole water body, and distributed evenly. After spraying 100 mg/L SCN on the surface of water with a volume of (3.14 x 20(2) x 50) cm3, by using the spraying value of 0.02 g/m2, 96 h later, no death of zebra fish was found.
  
  
  CONCLUSIONS
  From 30 to 60 min after spraying 100 mg/L SCN, with the value of 0.02 g/m2, on the surface of S. japonicum-infested water, the water infectivity can be eliminated, 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 surveillance and forecast sites.
authors.affiliation: Jiangsu Institute of Parasitic Diseases, Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Jiangsu Provincial Key Laboratory on Molecular Biology of Parasites, Wuxi 214064, China.
authors.forename: You-Sheng
authors.initials: YS
authors.lastname: Liang
authors.forename: Yun-Tian
authors.initials: YT
authors.lastname: Xing
authors.forename: Hong-Jun
authors.initials: HJ
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yong-Liang
authors.initials: YL
authors.lastname: Xu
authors.forename: Jian-Xia
authors.initials: JX
authors.lastname: Tang
authors.forename: Guo-Li
authors.initials: GL
authors.lastname: Qu
authors.forename: You-Zi
authors.initials: YZ
authors.lastname: Li
authors.forename: Le-Ping
authors.initials: LP
authors.lastname: Sun
authors.forename: Qing-Biao
authors.initials: QB
authors.lastname: Hong
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Dai
mesh_terms: D000336:Aerosols; D000818:Animals; D058487:Cercaria / Q000187:drug effects* / Q000472:pathogenicity; D002681:China / Q000453:epidemiology; D005260:Female; D008297:Male; D051379:Mice; D009026:Mortality; D009534:Niclosamide / Q000494:pharmacology* / Q000633:toxicity; D011159:Population Surveillance / Q000379:methods; D012549:Schistosoma japonicum / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology; D012554:Schistosomiasis japonica / Q000453:epidemiology / Q000469:parasitology / Q000517:prevention & control*; D012556:Schistosomicides / Q000494:pharmacology* / Q000633:toxicity; D013535:Suspensions; D013997:Time Factors; D014867:Water / Q000737:chemistry / Q000469:parasitology; D015027:Zebrafish / Q000502:physiology
chemical_list: D000336:Aerosols; D012556:Schistosomicides; D013535:Suspensions; D014867:Water; D009534:Niclosamide