Schistosoma is a parasite that infects humans, cattle, sheep, pigs and many other mammals. Schistosomiasis eggs in the feces of patients or infected animals can develop into infectious cercariae when they encounter snails in the water. People can be infected as soon as 10 seconds after touching the water containing the cercariae.

Schistosomiasis is endemic in 12 provinces (municipalities) south of the Yangtze River. In some areas of Sichuan Province, the intermediate host of schistosomiasis transmission, "snail", still exists, and local transmission may occur once an imported infection source is introduced. Therefore, there is a certain risk of infection.