The incubation period is1~ 3 months, with mild symptoms or no symptoms. Moderate and severe patients may have gastrointestinal symptoms such as loss of appetite, abdominal pain, intermittent diarrhea (mostly indigestion feces), nausea and vomiting, mainly abdominal pain. Abdominal pain is often located in the upper abdomen and the lower part of the right rib, and a few are around the umbilicus. It occurs on an empty stomach or after meals in the morning, with occasional severe pain and colic. Patients often have hyperactivity of bowel sounds, increased intestinal peristalsis and flatulence. Many patients have a history of automatic worm expulsion or insect vomiting. Children often have neurological symptoms such as poor sleep at night, grinding teeth and convulsions. A few patients may have edema and ascites due to long-term diarrhea and severe malnutrition, and severe and advanced patients may have exhaustion, collapse or convulsions.