Strongyloides

Aka: Strongyloides, Strongyloides stercoralis, Strongyloidiasis, Threadworm, Larva currens

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II. Epidemiology

  1. Nematode: Roundworm
  2. Responsible for most U.S. cases fatal Helminth disease
  3. Found in regions of poor sanitation
  4. Endemic areas
    1. Tropical Asia
    2. Sub-Saharan Africa
    3. Latin America
    4. Pockets in Rural southeastern United States
    5. Pockets in Eastern Europe

III. Pathophysiology

  1. Soil transmitted Helminth
  2. On soil contact, roundworm larvae penetrate skin
    1. Roundworms enter the venous system and are transported to the lungs
    2. Patient coughs, and worms are swallowed, resulting in intestinal infection
  3. Adult roundworms live in the Small Intestine and lay eggs
    1. Eggs may be passed in the stool and infect soil
    2. Eggs may also hatch and penetrate the Small Intestine wall, to recirculate via veins and into the lung
    3. Larvae may also infect perianal skin

IV. Risk Factors: Hyperinfection (Immunocompromised)

  1. Chronic Corticosteroid use
  2. Chemotherapy
  3. Human Immunodeficiency Virus (HIV)

V. Differential Diagnosis

  1. Peptic Ulcer Disease

VI. Symptoms

  1. Often asymptomatic in immunocompetent patients
  2. Larva currens
    1. Recurrent serpiginous Urticaria and associated Pruritus
    2. Onset in perianal area
    3. Migratory rash to buttocks, groin, trunk
  3. Gastrointestinal side effects
    1. Abdominal Pain or Abdominal Bloating
    2. Diarrhea
  4. Pulmonary involvement
    1. Cough
    2. Shortness of Breath
    3. Dyspnea
    4. Hemoptysis

VII. Labs

  1. Eosinophilia (blood or stool)
    1. May be only finding in immunocompetent patients
  2. Guaiac-positive stools
  3. Rhabditiform larvae present in sample
    1. Stool sample or duodenal aspiration
    2. False Negative test: 70% of cases

VIII. Management

  1. Ivermectin (now preferred agent)
    1. Dose: 200 mcg/kg orally daily for 2 days
    2. Repeat every 15 days for disseminated infection until stool testing negative (and then one more treatment)
    3. Continuous dosing daily for hyperinfection (e.g. Sepsis, Meningitis) continued until stool and Sputum negative for 2 weeks
  2. Other agents
    1. Albendazole 400 mg orally twice daily for 7 days (for asymptomatic of intestinal infection)
    2. Thiabendazole (not available, poorly tolerated, less effective)

IX. Complications: Hyperinfection

  1. Meningitis
  2. Septic Shock

X. Prognosis

  1. Hyperinfection mortality rate in immunosuppressed: 87%

XI. References

  1. Gilbert (2016) Sanford Guide, IOS version, accessed 9/12/2016
  2. Siddiqui (2001) Clin Infect Dis 33:1040-7 [PubMed]
  3. Schonau (2024) Am Fam Physician 109(6): 569-70 [PubMed]

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