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Hookworm Infection


By Richard D. Pearson, MD, Emeritus Professor of Medicine, University of Virginia School of Medicine

Hookworm infection is an infection of the intestines that can cause an itchy rash, respiratory and gastrointestinal problems, and eventually iron deficiency anemia due to ongoing loss of blood.

  • People can become infected when walking barefoot because hookworm larvae live in the soil and can penetrate the skin.

  • At first, people may have an itchy rash where the larvae penetrate the skin, then fever, coughing, and wheezing or abdominal pain, loss of appetite, and diarrhea.

  • Severe infections can cause loss of blood and anemia that is sometimes severe enough to cause fatigue and occasionally heart failure and widespread swelling.

  • Doctors diagnose the infection by identifying hookworm eggs in a stool sample.

  • The infection is treated with antiparasitic drugs such as albendazole.

About 740 million people are infected with hookworms, which are intestinal roundworms. The infection is most common in tropical areas where sanitation is poor. Hookworms thrive in warm, moist places.

Two species of hookworm cause infection in people:

  • Ancylostoma duodenale

  • Necator americanus

Both species are present in moist, hot areas of Africa, Asia, and the Americas. Ancylostoma duodenale is present in the Middle East, North Africa, and southern Europe. Necator americanus is present mainly in the Americas and Australia. It once was common in the southern part of the United States but is now rare there.

Life Cycle of the Hookworm

Eggs are passed in stool and hatch in the soil after 1 to 2 days if they are deposited in a warm, moist place on loose soil. Larvae emerge and live in the soil. When fully developed, the larvae can penetrate the skin. A person can become infected by walking barefoot or sitting in contaminated soil. Larvae of Ancylostoma duodenale can also cause infection when people consume food that contains the larvae.

Once larvae enter the body, they move through the lymphatic vessels and the bloodstream to the lungs. The larvae pass into the air spaces of the lungs and move up the respiratory tract. They are coughed up into the throat and swallowed. About a week after penetrating the skin, they reach the intestine. Once inside the intestine, the larvae develop into adults. They attach themselves by their mouth to the lining of the upper small intestine, where they feed on blood and produce substances that keep blood from clotting.


Many people with hookworm infection do not have symptoms. However at the start of a hookworm infection, an itchy, red, raised rash (ground itch) may develop where the larvae penetrate the skin. The movement of the larvae through the lungs can cause fever, coughing, and wheezing.

When adult worms first attach in the intestine, they can cause pain in the upper abdomen, loss of appetite, diarrhea, and weight loss. Over time, anemia develops as blood is lost and people become iron deficient. Anemia causes fatigue, and children with severe anemia may not grow normally. Severe anemia may also cause heart failure and widespread tissue swelling.


  • Examination of a stool sample

  • Blood tests to check for anemia and nutritional deficiencies

Hookworm infection diagnosis is made by identifying hookworm eggs in a sample of stool. Stool should be examined within several hours after defecation.

Blood tests for anemia and nutritional deficiencies, particularly iron, are also done.


Hookworm infection prevention involves the following:

  • Using sanitary toilet facilities

  • Preventing the skin from directly contacting the soil (for example, by wearing shoes and using a tarp or other barrier when seated on the ground)

  • Treating dogs and cats for hookworm to prevent them from spreading hookworms to people.

In areas where the infection is common, public health officials sometimes periodically treat people who are likely to be exposed to hookworms to prevent the infection.


  • Albendazole or mebendazole (drugs used to eliminate worms—antihelminthic drugs)

  • For anemia, iron supplements

To treat hookworm infection, a doctor prescribes albendazole or mebendazole, taken by mouth. Because of possible adverse effects to the fetus, these drugs cannot be taken by pregnant women.

Iron supplements are given to people with anemia.

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