The damage caused by hookworm parasitism in human body can be divided into two stages: larval and adult, most of the mildly infected people do not have clinical symptoms, about 10% of the heavier infected people appear a variety of clinical damage, the main manifestations are as follows: 1. Clinical manifestations caused by larvae are mainly hookworm dermatitis and respiratory symptoms, especially when the larvae drilled into, there is a burning or pinprick sensation in the local area, and then there is a congestive blotches or papules with strange itching, which become blisters after 1-2 days, and the symptoms usually disappear and the lesions heal in about 4-10 days. Within 1 week of infection, there can also be pharyngeal itching, coughing, coughing up sputum, and in severe cases, there is even a severe dry cough, asthma, chills, fever, blood in sputum, etc., which lasts for several days to months before disappearing.2. Clinical damages caused by adult worms are mainly anemia due to chronic blood loss, which is the main feature of hookworm disease, and a variety of gastrointestinal symptoms caused by mucous membrane trauma. The main manifestations of anemia are pallor, weakness of the limbs, mental weakness, dizziness and reduced ability to work, etc. In severe cases, there are panic, shortness of breath, swelling of the face and lower limbs, anemic heart disease and cardiac insufficiency. Gastrointestinal symptoms may include epigastric discomfort, pain, loss of appetite, dyspepsia, diarrhea and emaciation, and in some severe cases, gastrointestinal bleeding. Children may have xerophagia such as eating raw rice and soil, and the more severe cases in infants and young children can lead to growth and developmental disorders.