A drug intervention trial (praziquantel) against the Schistosoma japonicum parasite in China.

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Background Zoonotic schistosomiasis japonica is a major public health problem in China. Bovines, particularly water buffaloes, are thought to play a major role in the transmission of schistosomiasis to humans in China. Preliminary results (1998-2003) of a praziquantel (PZQ)-based pilot intervention study we undertook provided proof of principle that water buffaloes are major reservoir hosts for Schistosoma japonicum in the Poyang Lake region, Jiangxi Province. Methods and Findings We undertook a cluster-randomised intervention trial (2004-2007) in Hunan and Jiangxi Provinces in China, with increased power and more general applicability to the lake and marshlands regions of southern China. The trial involved four matched pairs of villages with one village within each pair randomly selected as a control (human PZQ treatment only), leaving the other as the intervention (human and bovine PZQ treatment). A sentinel cohort of people to be monitored for new infections for the duration of the study was selected from each village. Results showed that combined human and bovine chemotherapy with PZQ had a greater effect on human incidence than human PZQ treatment alone. This was supported by Poisson regression analyses yielding crude and adjusted (for water contact) relative risks of 0.5 and 0.54 Conclusions The results from this study supported by previous experimental evidence, confirms that bovines are the major reservoir host of human schistosomiasis in the lake and marshland regions of southern China, and reinforce the rationale for the development and deployment of a transmission blocking anti-S. japonicum vaccine targeting bovines.