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For further information, see CMDT Part 35-20: Ascariasis

Key Features

Essentials of Diagnosis

  • Transient cough, urticaria, pulmonary infiltrates

  • Eosinophilia

  • Nonspecific abdominal symptoms

  • Eggs in stools; adult worms occasionally passed

General Considerations

  • Ascaris lumbricoides is the most common intestinal helminth

  • Infection follows ingestion of eggs in contaminated food

  • Larvae hatch in the small intestine, penetrate into the bloodstream, migrate to lungs, and then back to the gastrointestinal tract where they develop into adult worms

  • Adult worms can be up to 40 cm long and live for 1–2 years


  • Causes about 800 million infections, with 12 million acute cases and 10,000 or more deaths annually

  • Prevalence is high wherever there is poor hygiene and sanitation or where human feces are used as fertilizer

  • Heavy infections are most common in children

Clinical Findings

Symptoms and Signs

  • Most infected persons are asymptomatic

  • The following symptoms develop in a small number of patients during migration of worms through the lungs

    • Fever

    • Nonproductive cough

    • Chest pain

    • Dyspnea

    • Eosinophilia

    • Eosinophilic pneumonia (occasionally)

  • Rarely, larvae lodge ectopically in the brain, kidney, eye, spinal cord, and other sites and may cause local symptoms

  • With heavy infection, abdominal discomfort may be seen

  • Adult worms may migrate and be coughed up, vomited, or may emerge through the nose or anus

  • They may also migrate into the common bile duct, pancreatic duct, appendix, and other sites, which may lead to

    • Cholangitis

    • Cholecystitis

    • Pyogenic liver abscess

    • Pancreatitis

    • Obstructive jaundice

    • Appendicitis

  • With very heavy infestations, masses of worms may cause

    • Intestinal obstruction

    • Volvulus

    • Intussusception

    • Death

  • Moderate to high worm loads in children are also associated with nutritional abnormalities

Differential Diagnosis

  • Asthma

  • Allergic bronchopulmonary aspergillosis (ABPA)

  • Acute eosinophilic pneumonia (Löffler syndrome)

  • Paragonimiasis

  • Tropical pulmonary eosinophilia (Wuchereria bancrofti, Brugia malayi)

  • Hookworm disease

  • Strongyloidiasis

  • Toxocariasis (visceral larva migrans)

  • Peptic ulcer disease

  • Other causes of cholangitis, cholecystitis, pancreatitis, appendicitis, diverticulitis


Laboratory Tests

  • Diagnosis is made after adult worms emerge from the mouth, nose, or anus or by identifying characteristic eggs in the feces, usually with the Kato-Katz technique

  • Eosinophilia is marked during worm migration but may be absent during intestinal infection

Imaging Studies

  • Chest radiographs may show pulmonary infiltrates

  • Plain abdominal films and ultrasonography can demonstrate worms, with filling defects in contrast studies and at times evidence of intestinal or biliary obstruction



  • All infections should be treated

  • Treatments of choice

    • Albendazole (400 mg single dose)

    • Mebendazole (500 mg single dose or 100 mg twice daily for 3 days)

    • Pyrantel pamoate (11 mg/kg single dose, ...

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