Heterophyes infection is caused by consuming raw or brackish water or undercooked freshwater fish that has been contaminated. Depending on the species, flukes are parasitic flatworms that affect different body parts, such as the blood vessels, digestive tract, lungs, and liver.
Metacercariae are parasitic worms that attach to the lining of the small intestine if they are eaten. There, they grow into adults that are about 1.0–1.7 mm long and 0.3–0.4 mm wide. Flukes could lay eggs in the mucosa, and those eggs would then get into the bloodstream through the lymphatic system.
Heterophyes infection grows naturally in East Asia but is also often found in the Middle East, Sudan, Egypt, and southeastern Europe.