Most individuals develop symptoms only months or even years after infection. Symptoms mostly depend on the species of blood fluke and where in the body the fluke lays most of its eggs. Schistosoma japonicum typically settles in blood vessels around the intestines, which is why its symptoms usually include abdominal pain, loss of appetite, diarrhea (with or without blood), and constipation; in more severe cases, it can spread to the nervous system and cause symptoms like convulsions, speech disturbances, and blurring of vision.
A subset of patients can develop symptoms a week to a month after getting the parasite. These individuals can experience flu-like symptoms that include fever, headache, fatigue, muscle pain, coughing, diarrhea, and abdominal pain.