When there are parasites in the intestine, they not only absorb glucose from the body through the intestinal wall, but also release toxic substances that irritate the intestinal wall. When there are too many parasites in the intestine, the invasion of the intestinal wall will gradually increase, so the patient will have abdominal pain, and the pain will come at irregular intervals. Since parasites consume a lot of nutrients, long-term parasitic infections are accompanied by malnutrition, and the body is thin even after eating a lot. Some people are infected with pinworms, which crawl out of the anus when the female enters the egg-laying stage and ovulate outside the anus, causing symptoms such as anal dampness and anal itching.