The disease is caused by contact with fresh water containing the parasites. These parasites are from infected freshwater snails. The disease is very common among children in developing countries, as they are more likely to play in water. Other high-risk groups include farmers, fishermen, and people using unclean water. It is a helminth infections. Eggs of the parasite may be found in urine or stool. Antibodies may also be found in the blood.