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Hookworm infection

Definition

Hookworm infection is caused by roundworms. The disease affects the small intestine and lungs.

Alternative Names

Hookworm disease; Ground itch; Ancylostoma duodenale infection; Necator americanus infection; Parasitic infection - hookworm

Causes

The infection is caused by infestation with any of the following roundworms:

  • Necator americanus
  • Ancylostoma duodenale
  • Ancylostoma ceylanicum
  • Ancylostoma braziliense

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.

Symptoms

Symptoms may include:

Most people have no symptoms once the worms enter the intestines.

Exams and Tests

Tests that can help diagnose the infection include:

Treatment

The goals of treatment are to:

  • Cure the infection
  • Treat complications of anemia
  • Improve nutrition

Parasite-killing drugs such as albendazole, mebendazole, or pyrantel pamoate are often prescribed.

Symptoms and complications of anemia are treated, if needed. The health care provider will likely recommend increasing the amount of protein in your diet.

Outlook (Prognosis)

You will have a complete recovery if you get treated before serious complications develop. Treatment gets rid of the infection.

Possible Complications

Health problems that may result from hookworm infection include:

When to Contact a Medical Professional

Contact your provider for an appointment if symptoms of hookworm infection develop.

Prevention

Handwashing and wearing shoes will reduce the likelihood of infection.

Gallery

Hookworm - mouth of the organism
This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - mouth of the organism
This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - mouth of the organism
This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - mouth of the organism
This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - mouth of the organism
This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)
Digestive system organs
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.

References

Diemert DJ. Nematode infections. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 335.

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.

Last reviewed September 1, 2021 by Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate 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..

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