Hookworm infection

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

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

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 weakening their immune system and 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:

Abdominal discomfort
Cough
Diarrhea
Fatigue
Fatigue
Fatigue is a feeling of weariness, tiredness, or lack of energy.

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Fever
Gas
Itchy rash
Loss of appetite
Loss of appetite
A decreased appetite is when your desire to eat is reduced. The medical term for a loss of appetite is anorexia.

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Nausea, vomiting
Pale skin
Pale skin
Paleness is an abnormal loss of color from normal skin or mucous membranes.

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

Exams and Tests

Tests that can help diagnose the infection include:

Complete blood count (CBC) with differential
Complete blood count
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
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Differential
The blood differential test measures the percentage of each type of white blood cell (WBC) that you have in your blood. It also reveals if there are...
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Stool ova and parasites exam
Stool ova and parasites exam
Stool ova and parasites exam is a lab test to look for parasites or eggs (ova) in a stool sample. The parasites are associated with intestinal infec...
Image

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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. Your 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:

Iron deficiency anemia, caused by loss of blood
Iron deficiency anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are man...
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Nutritional deficiencies
Severe protein loss with fluid buildup in the abdomen (ascites)
Ascites
Ascites is the build-up of fluid in the space between the lining of the abdomen and abdominal organs.
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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.

Open References

References

Diemert DJ. Nematode infections. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 327.

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.

Hookworm - mouth of the organism - illustration
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
illustration
Hookworm - close-up of the organism - illustration
This is the mouth part of the hookworm Ancylostoma duodenale. The hookworm uses sharp, curved cutting plates to attach to the lining of the intestine where it sucks blood for nourishment. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - close-up of the organism
illustration
Hookworm - Ancylostoma caninum - illustration
This is a photograph of a hookworm on the lining of the intestine. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - Ancylostoma caninum
illustration
Hookworm egg - illustration
This is a hookworm egg. Hookworms hatch in damp vegetation. Their larvae can enter the human body through the skin, even without cuts or abrasions. Once through the skin, they begin the next step of their life cycle.
Hookworm egg
illustration
Hookworm rhabditiform larva - illustration
The larva of a hookworm is visible in the center of this photograph.
Hookworm rhabditiform larva
illustration
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration

Hookworm - mouth of the organism - illustration
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
illustration
Hookworm - close-up of the organism - illustration
This is the mouth part of the hookworm Ancylostoma duodenale. The hookworm uses sharp, curved cutting plates to attach to the lining of the intestine where it sucks blood for nourishment. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - close-up of the organism
illustration
Hookworm - Ancylostoma caninum - illustration
This is a photograph of a hookworm on the lining of the intestine. (Image courtesy of the Centers for Disease Control and Prevention.)
Hookworm - Ancylostoma caninum
illustration
Hookworm egg - illustration
This is a hookworm egg. Hookworms hatch in damp vegetation. Their larvae can enter the human body through the skin, even without cuts or abrasions. Once through the skin, they begin the next step of their life cycle.
Hookworm egg
illustration
Hookworm rhabditiform larva - illustration
The larva of a hookworm is visible in the center of this photograph.
Hookworm rhabditiform larva
illustration
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration

A Closer Look

Talking to your MD

Self Care

Tests for Hookworm infection

Review Date: 8/26/2023

Reviewed 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 C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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Health Library

Hookworm infection

Causes

Symptoms

Fatigue

Loss of appetite

Pale skin

Exams and Tests

Complete blood count

Differential

Stool ova and parasites exam

Treatment

Protein in your diet

Outlook (Prognosis)

Possible Complications

Iron deficiency anemia

Ascites

When to Contact a Medical Professional

Prevention

References

Hookworm - mouth of the organism - illustration

Hookworm - mouth of the organism

Hookworm - close-up of the organism - illustration

Hookworm - close-up of the organism

Hookworm - Ancylostoma caninum - illustration

Hookworm - Ancylostoma caninum

Hookworm egg - illustration

Hookworm egg

Hookworm rhabditiform larva - illustration

Hookworm rhabditiform larva

Digestive system organs - illustration

Digestive system organs