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 ...