Schistosoma haematobium trichinella meets a suitable intermediate host snail in the water, invades the snail body and gradually develops. First formed a bag-shaped mother larva, the embryonic cells in the body can produce many sub-cellular larvae, sub-cellular larvae escaped into the liver of the snail, the embryonic cells in the body of the proliferation, the formation of a number of batches of tailed larvae.

Tailed larvae leave the snail after maturity, often distributed in the surface layer of the water, people or animals in contact with the water containing tailed larvae, tailed larvae through the skin and infection.

Extended information:

There are many factors affecting the invasion and escape of caecilians from the nail snail, the most important factor is the temperature of the water, which is generally in the range of 15-35 ℃, and the optimal temperature is 20-25 ℃; the light has a good effect on caecilians' escape;

The water's pH is in the range of 6.6-7.8, which is unaffected by the caecilians' escape. After escaping, the caecilians are mainly distributed under the surface of the water, and their life span is generally 1 to 3 days. The survival time of the caecilians and their infectivity varies with the ambient temperature and the nature of the water and the length of time after the caecilians have escaped.

Baidu Encyclopedia - Schistosoma haematobium