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Hookworm
Definition
Hookworm is a condition caused by roundworms that affects the small intestine and lungs.
Causes
The disorder is caused by infestation with the 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. It affects about 1 billion people worldwide. 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 where people who have hookworm have made feces.
The larvae (immature form of the worm) get into the skin. The larvae move to the lungs via the bloodstream and enter the airways. The worms are about 1/2 inch long.
After traveling up the windpipe, the larva 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. Adult worms and larvae are released in the feces.
Symptoms
- Abdominal discomfort
- Blood in the stool
- Bloody sputum
- Cough
- Diarrhea
- Fatigue
- Fever
- Gas
- Itchy rash
- Loss of appetite
- Nausea, vomiting
- Pale skin
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
- Stool ova and parasites exam
This disease may also affect the results of a D-xylose absorption test.
Treatment
The goals of treatment are to:
- Cure the infection
- Treat complications of anemia
- Improve nutrition
Parasite-killing medications such as albendazole, mebendazole, or pyrantel pamoate are usually prescribed. Ivermectin, used for other worm infections, does not work for hookworm infections.
Symptoms and complications of anemia are treated as they arise. The doctor 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
- Iron deficiency anemia caused by loss of blood
- Nutritional deficiencies
- Severe protein loss with fluid buildup in the abdomen (ascites)
When to Contact a Medical Professional
Call for an appointment with your health care provider if symptoms of hookworm infection develop.
Prevention
Developing countries need to improve sanitation measures to prevent infection.
References
Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 378.
Maguire JH. Intestinal nematodes (roundworms). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Disease. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 287.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, PHD, MD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
