Hookworm disease, also called uncinariasis or ground itch, is an infection of the upper intestine caused by Ancylostoma duodenale (found in the eastern hemisphere) or Necator americanus (in the western hemisphere). Sandy soil, high humidity, a warm climate, and failure to wear shoes all favor its transmission. In the United States, hookworm disease is most common in the southeast. Although this disease can cause cardiopulmonary complications, it's rarely fatal, except in debilitated people and infants younger than age 1.
Both forms of hookworm disease are transmitted to humans through direct skin penetration (usually in the foot) by hookworm larvae in soil contaminated with feces containing hookworm ova. These ova develop into infectious larvae in 1 to 3 days. Larvae travel through the lymphatics to the pulmonary capillaries, where they penetrate alveoli and move up the bronchial tree to the trachea and epiglottis, where they're swallowed and enter the GI tract. When they reach the small intestine, they mature, attach to the jejunal mucosa, and suck blood, oxygen, and glucose from the intestinal wall. These mature worms then deposit ova, which are excreted in the stool, starting the cycle anew. Hookworm larvae mature in approximately 5 to 6 weeks.
Hookworm disease, affecting billions of people worldwide, is most common in moist tropical and subtropical regions. There's little risk of aquiring hookworm disease in the United States because of advances in sanitization and waste control.
Most cases of hookworm disease produce few symptoms and may be overlooked until worms are passed in the stool. The earliest signs and symptoms include irritation, pruritus, and edema at the site of entry, which are sometimes accompanied by secondary bacterial infection with pustule formation.
When the larvae reach the lungs, they may cause pneumonitis and hemorrhage with fever, sore throat, crackles, and cough. Finally, intestinal infection may cause fatigue, nausea, weight loss, dizziness, melena, and uncontrolled diarrhea.
In severe and chronic infection, anemia from blood loss may lead to cardiomegaly (a result of increased oxygen demands), heart failure, and generalized massive edema.
CONFIRMING DIAGNOSIS Identification of hookworm ova in the stool confirms the diagnosis. Anemia suggests severe chronic infection.
Treatment of hookworm infection includes administering mebendazole or albendazole, and providing an iron-rich diet or iron supplements to prevent or correct anemia.
❑Obtain a complete history, with special attention to travel or residency in endemic areas. Note the sequence and onset of symptoms. Interview the patient's family and other close contacts to see if they have symptoms.
❑Carefully assess the patient, noting signs of entry, lymphedema, and respiratory status.
❑Perform meticulous hand hygiene after every patient contact.
❑For severe anemia, administer oxygen, if ordered, at low to moderate flow. Be sure the oxygen is humidified because the patient may already have upper airway irritation from the parasites. Encourage coughing and deep breathing to stimulate removal of blood or secretions from involved lung areas and to prevent secondary infection. Plan your care to allow frequent rest periods because the patient may tire easily. If anemia causes immobility, reposition the patient often to prevent skin breakdown.
❑Closely monitor intake and output. Note the frequency of diarrhea and the quantity of stools. Dispose of feces promptly, and wear gloves when doing so.
❑To help assess nutritional status, weigh the patient daily. To combat malnutrition, emphasize the importance of good nutrition, with particular attention to foods high in iron and protein. If the patient receives iron supplements, explain that they will darken stools. Administer antihelmintics on an empty stomach, but without a purgative.
❑To help prevent reinfection, educate the patient in proper hand-hygiene technique and sanitary disposal of feces. Tell him to wear shoes in endemic areas.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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