IMPACT OF WATER TEMPERATURE ON SHEDDING AND INFECTIVITY OF CERCARIAE OF SCHISTOSOMA JAPONICUM / 中国血吸虫病防治杂志

ABSTRACT

Objective To observe the impact of water temperature on shedding and infectivity of the cercariea of Schistosoma japonicum under laboratory condition. Methods Infected snails were exposed to 1, 5, 10, 15, 20, 25, 30, 35℃ and 40℃ water for 4 hours for shedding of cercariae respectively, the shedding rates and total numbers of cercariae shed were investigated. The mice were infected with cercariae in 1, 10, 20, 30℃ and 40℃ water for 30 minutes respectively, the infection rates and mean worm burden of mice were investigated. Results The cercariae were shed from infected snails with Jiangsu or Yunnan isolate of [WT5”BX]S. japonicum in water ranged from 1℃ to 40℃, but the fittest water temperatures range for shedding of cercariae of Yunnan isolate of S.japonicum[WT5”BZ] is from 20℃ to 35℃, while fittest range for Jiangsu isolate is from 15℃ to 35℃. All of the infection rates of mice infected with cercariae of Jiangsu isolate of S.japonicum in the water ranged from 1℃ to 40℃ were 100.0%. Infection rates of mice infected with cercariae of Yunnan isolate of S. japonicum in the water ranged from 1℃ to 40℃ were more than 83.3%. Conclusions When infected snails are exposed to the water with temperature ranged from 1℃ to 40℃ it is possible for cercariae to shed and infect the final hosts . It is suggested that there is a possibility of infection with S.japonicum when contacting the water near marshlands with infected snails in winter.