title: Five-year longitudinal assessment of the downstream impact on schistosomiasis transmission following closure of the Three Gorges Dam.
abstract: BACKGROUND
  Schistosoma japonicum is a major public health concern in the Peoples' Republic of China (PRC), with about 800,000 people infected and another 50 million living in areas at risk of infection. Based on ecological, environmental, population genetic and molecular factors, schistosomiasis transmission in PRC can be categorised into four discrete ecosystems or transmission modes. It is predicted that, long-term, the Three Gorges Dam (TGD) will impact upon the transmission of schistosomiasis in the PRC, with varying degree across the four transmission modes.
  
  
  RESULTS
  We undertook longitudinal surveillance from 2002 to 2006 in sentinel villages of the three transmission modes below the TGD across four provinces (Hunan, Jiangxi, Hubei and Anhui) to determine whether there was any immediate impact of the TGD on schistosomiasis transmission. Eight sentinel villages were selected to represent both province and transmission mode. The primary end point measured was human incidence. Here we present the results of this five-year longitudinal cohort study. Results showed that the incidence of human S. japonicum infection declined considerably within individual villages and overall mode over the course of the study. This is also reflected in the yearly odds ratios (adjusted) for infection risk that showed significant (P<0.01) downward trends in all modes over the follow-up period.
  
  
  CONCLUSIONS
  The decrease in human S. japonicum incidence observed across all transmission modes in this study can probably be attributed to the annual human and bovine PZQ chemotherapy. If an increase in schistosome transmission had occurred as a result of the TGD, it would be of negligible size compared to the treatment induced decline seen here. It appears therefore that there has been virtually no immediate impact of the TGD on schistosomiasis transmission downstream of the dam.
authors.affiliation: Molecular Parasitology Laboratory, Infectious Diseases Division, Queensland Institute of Medical Research, Herston, Brisbane, Queensland, Australia.
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Gray
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Thrift
authors.forename: Gail M
authors.initials: GM
authors.lastname: Williams
authors.forename: Feng
authors.initials: F
authors.lastname: Zheng
authors.forename: Yue-Sheng
authors.initials: YS
authors.lastname: Li
authors.forename: Jiagang
authors.initials: J
authors.lastname: Guo
authors.forename: Honggen
authors.initials: H
authors.lastname: Chen
authors.forename: Tianping
authors.initials: T
authors.lastname: Wang
authors.forename: Xin Jiang
authors.initials: XJ
authors.lastname: Xu
authors.forename: Rong
authors.initials: R
authors.lastname: Zhu
authors.forename: Hongqing
authors.initials: H
authors.lastname: Zhu
authors.forename: Chun Li
authors.initials: CL
authors.lastname: Cao
authors.forename: Dan Dan
authors.initials: DD
authors.lastname: Lin
authors.forename: Zhen Yuan
authors.initials: ZY
authors.lastname: Zhao
authors.forename: Robert S
authors.initials: RS
authors.lastname: Li
authors.forename: George M
authors.initials: GM
authors.lastname: Davis
authors.forename: Donald P
authors.initials: DP
authors.lastname: McManus
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage; D002417:Cattle; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004358:Drug Therapy / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011223:Praziquantel / Q000008:administration & dosage; D011446:Prospective Studies; D012549:Schistosoma japonicum; D012552:Schistosomiasis / Q000453:epidemiology* / Q000635:transmission*; D018571:Sentinel Surveillance; D055815:Young Adult
chemical_list: D000871:Anthelmintics; D011223:Praziquantel