There are more types of parasites and different types of parasites show different symptoms. The presence of parasites in the human body may cause symptoms such as weight loss, anemia, ulcers, allergies, etc., such as tapeworms, roundworms, amoebas, schistosomiasis, and so on. 1. Wasting, anemia: the nutrients needed for the growth, development and reproduction of parasites in the host mainly come from the host. For example, tapeworms and roundworms are parasitized in the intestines, sucking up a lot of nutrients and affecting the absorption function of the intestines, resulting in malnutrition and wasting of the host. For example, hookworms attach to the intestinal wall and absorb a large amount of blood, causing anemia in the host. 2. Ulcers: The excretions, secretions and decomposition products of dead parasites have toxic effects on the host. For example, when amoeba invades the intestinal mucosa and liver, it secretes histolytic enzymes that dissolve tissues and cells, causing intestinal ulcers and liver abscesses in the host. 3. Allergy: The metabolites of parasites and the decomposition products of dead worms are antigenic and can sensitize the host, causing local or systemic allergic reactions. For example, schistosome egg granuloma is an immunopathological change in the surrounding tissues caused by the secretion of trichinella within the eggs of Schistosoma japonicum. When the above symptoms occur, it is recommended to seek prompt medical attention, follow the doctor’s instructions for further examination, clarify the cause with the doctor’s help, and carry out targeted treatment or therapy.