Often found in monkeys in Africa and Asia. Parasitizes in the intestines. Males (9.5 × 0.56 millimeters) and females (16 × 0.7 millimeters) are similar in size, size and shape to hookworms. The eggs also resemble those of hookworms, but larger (84 × 40 micrometers). Infection occurs when the invasive larvae are swallowed. Having penetrated into the intestine, the larvae penetrate into the thickness of the mucous membrane, forming parasitic nodules. After 6-8 days, they again go out into the intestinal lumen, attach and gradually turn into sexually mature helminths, which are hematophages.