Diagnosis

The following patients should be investigated for strongyloidiasis:

• travelers or people who migrate from an endemic area and develop the following within 3-4 weeks of travel:
  • persistent unexplained eosinophilia
    • should be investigated further in the first instance by repeating the test to confirm the result
    • other common causes (atopy, drugs) should be excluded by obtaining a carful history of the patient
    • present during the acute and chronic stages, but may be absent with dissemination (2)
  • gastrointestinal symptoms: nausea, vomiting, abdominal pain, bloating
  • pulmonary symptoms: fever, wheeze, persistent cough
  • cutaneous symptoms: larva currens, hives, or pustules

Further investigations carried out in patients include:

• three stool samples for microscopy - collected on separate days
  • although the test has low sensitivity for detecting S stercoralis (around 50%) it is considered to be the gold standard for diagnosis
  • larvae usually appear in stools 3-4 weeks after dermal penetration.
• blood test for S stercoralis serology
  • detects IgG to a filariform larval antigen

In patients with massive autoinfection the rhabditiform larvae are present in sputum and faeces.

Reference:

• (1) Greaves D et al. Strongyloides stercoralis infection. BMJ. 2013;347:f4610