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For further information, see CMDT Part 35-23: Strongyloidiasis

Key Features

Essentials of Diagnosis

  • Transient pruritic skin rash and lung symptoms

  • Anorexia, diarrhea, abdominal discomfort

  • Larvae detected in stool

  • Hyperinfection in immunocompromised persons; larvae detected in sputum or other fluids

  • Eosinophilia

General Considerations

  • Infection is caused by Strongyloides stercoralis

  • The primary host is humans

  • The parasite's life cycle

    • Maintains its life cycle both within humans and in soil

    • Infection occurs when filariform larvae in soil penetrate the skin, enter the bloodstream, and are carried to the lungs and ascend the bronchial tree to the glottis

    • The larvae are then swallowed and carried to the duodenum and upper jejunum, where they mature to the adult stage

  • Autoinfection can occur in humans, when some rhabditiform larvae develop into filariform larvae that penetrate the intestinal mucosa or perianal skin, and enter the circulation

  • Parasite can cause severe infections in immunocompromised persons due to its ability to replicate in humans


  • Infects tens of millions of persons in tropical and subtropical regions

  • Endemic in some temperate regions of North America, Europe, Japan, and Australia

  • A related parasite, Strongyloides fuelleborni, infects humans in parts of Africa and New Guinea

Clinical Findings

Symptoms and Signs

  • Most infected persons are asymptomatic

Acute syndrome

  • Pruritic, erythematous, maculopapular rash, usually of the feet

  • Pulmonary symptoms (including dry cough, dyspnea, and wheezing)

  • Eosinophilia

  • Gastrointestinal symptoms

Chronic infection

  • Epigastric pain, nausea, diarrhea, and anemia

  • Maculopapular or urticarial rashes of the buttocks, perineum, and thighs due to migrating larvae

  • Large worm burdens can lead to malabsorption or intestinal obstruction

  • Eosinophilia is common but may fluctuate

Hyperinfection syndrome

  • Dissemination of large numbers of filariform larvae to lungs, CNS, kidneys, and liver in immunocompromised persons

  • Persons at risk include

    • Those receiving corticosteroids and other immunosuppressive medications

    • Those with hematologic malignancies, malnutrition, or alcoholism

    • Those infected with AIDS

  • Pulmonary findings

    • Pneumonitis

    • Cough

    • Hemoptysis

    • Respiratory failure

    • Sputum may contain adult worms, larvae, and eggs

  • CNS disease

    • Meningitis

    • Brain abscesses

    • Cerebrospinal fluid may contain larvae

  • Gastrointestinal symptoms

    • Abdominal pain

    • Nausea, vomiting

    • Diarrhea

    • More severe findings related to intestinal obstruction, perforation, or hemorrhage

    • Bacterial sepsis, probably secondary to intestinal ulcerations

  • Various presentations can progress to shock and death

Differential Diagnosis

  • Hookworm disease

  • Ascariasis

  • Giardiasis

  • Amebiasis

  • Acute eosinophilic pneumonia

  • Tropical pulmonary eosinophilia

  • Peptic ulcer disease

  • Cutaneous larva migrans


Laboratory Tests

Detection of eggs and larva

  • Eggs are seldom found in feces

  • Diagnosis usually based on identification of rhabditiform larvae in stool or duodenal contents


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