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

Demographics

• 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

Diagnosis

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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