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For further information, see CMDT Part 35-22: Hookworm Disease

Key Features

Essentials of Diagnosis

  • Transient pruritic skin rash and lung symptoms

  • Anorexia, diarrhea, abdominal discomfort

  • Iron deficiency anemia

  • Characteristic eggs and occult blood in the stool

General Considerations

  • Infection with Ancylostoma duodenale and Necator americanus is very common, especially in most tropical and subtropical regions

  • When eggs are deposited on warm moist soil they hatch, releasing larvae that remain infective for up to a week

  • With contact, the larvae penetrate skin and migrate in the bloodstream to the pulmonary capillaries

  • In the lungs, larvae penetrate into alveoli and then are carried by ciliary action upward to the bronchi, trachea, and mouth

  • After being swallowed, they reach and attach to the mucosa of the upper small bowel, where they mature to adult worms

    • Worms suck blood at attachment site

    • Blood loss is proportionate to worm burden

Demographics

  • Prevalence is estimated at about 500 million, causing approximately 65,000 deaths each year

Clinical Findings

Symptoms and Signs

  • Most infected persons are asymptomatic

  • A pruritic maculopapular rash (ground itch) may occur at the site of larval penetration

  • Pulmonary symptoms may be seen during larval migration through the lungs

    • Dry cough

    • Wheezing

    • Low-grade fever

  • Eosinophilia is common, especially during the phase of worm migration

  • About 1 month after infection, gastrointestinal symptoms may develop

    • Epigastric pain

    • Anorexia

    • Diarrhea

  • Persons chronically infected with large worm burdens may have

    • Abdominal pain

    • Anorexia

    • Diarrhea

    • Pallor, weakness, dyspnea, heart failure due to marked iron deficiency anemia

    • Hypoalbuminemia, edema, and ascites due to protein malnutrition

    • May have impairment in growth and cognitive development in children

  • Infection with the dog hookworm Ancylostoma caninum can uncommonly lead to

    • Abdominal pain

    • Diarrhea

    • Eosinophilia

    • Intestinal ulcerations and regional lymphadenitis

Differential Diagnosis

  • Ascariasis

  • Strongyloidiasis

  • Paragonimiasis

  • Tapeworm (especially Diphylobothrium latum with associated anemia)

  • Tuberculosis

  • Allergic bronchopulmonary aspergillosis (ABPA)

  • Mycoplasma pneumoniae infection

  • Iron deficiency anemia due to other causes, eg, gastrointestinal malignancy

Diagnosis

  • Diagnosis is based on the demonstration of characteristic eggs in feces

  • Concentration techniques are usually not needed

  • Microcytic anemia, occult blood in the stool, and hypoalbuminemia are common

  • Eosinophilia is common, especially during worm migration

Treatment

Medications

  • Albendazole (single 400 mg orally dose) or mebendazole (100 mg orally twice daily for 3 days)

    • These drugs are teratogenic

    • Occasional adverse effects are diarrhea and abdominal pain

  • Pyrantel pamoate and levamisole are also effective

  • Anemia should be managed with iron replacement and, for severe symptomatic anemia, blood transfusion

  • Mass treatment of children with single doses of albendazole or mebendazole at regular intervals limits worm burdens and the extent of disease and is advocated by the World Health Organization

Outcome

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