Hookworm infection is caused by roundworms. The disease affects the small intestine and lungs.
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The infection is caused by infestation with any of the following roundworms:
The first two roundworms affect humans only. The last two types also occur in animals.
Hookworm disease is common in the moist tropics and subtropics. In developing nations, the disease leads to the death of many children by increasing their risk for infections that their bodies would normally fight off.
There is very little risk of getting the disease in the United States because of advances in sanitation and waste control. The important factor in getting the disease is walking barefoot on ground where there are feces of people who are infected with hookworm.
The larvae (immature form of the worm) enter the skin. The larvae move to the lungs via the bloodstream and enter the airways. The worms are about one half inch (1 centimeter) long.
After traveling up the windpipe, the larvae are swallowed. After the larvae are swallowed, they infect the small intestine. They develop into adult worms and live there for 1 or more years. The worms attach to the intestinal wall and suck blood, which can result in iron deficiency anemia and protein loss. Adult worms and larvae are released in the feces.
Hotez PJ. Hookworms (Necator americanus and Ancylostoma spp.). In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 318.
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.