USMLE

Strongyloides stercoralis (threadworm)

801 views
Parasites
  1. Giardia lamblia
  2. Toxoplasma gondii
  3. Entamoeba histolytica
  4. Cryptosporidium
  5. Naegleria fowleri
  6. Trypanosoma brucei
  7. Plasmodium Overview
  8. Plasmodium Disease (Malaria)
  9. Babesia
  10. Trypanosoma cruzi
  11. Leishmania
  12. Trichomonas vaginalis
  13. Enterobius vermicularis (pinworm)
  14. Ascaris lumbricoides (giant roundworm)
  15. Strongyloides stercoralis (threadworm)
  16. Ancyclostoma and Necator
  17. Trichinella spiralis
  18. Trichuris trichiura (whipworm)
  19. Toxocara canis
  20. Onchocerca volvulus
  21. Loa loa
  22. Wuchereria bancrofti
  23. Taenia solium
  24. Diphyllobothrium latum
  25. Echinococcus granulosus
  26. Schistosoma
  27. Clonorchis sinensis
  28. Sarcoptes scabiei (Scabies)
  29. Pediculus humanis and Phthirus pubis (Lice)
  • Strongyloides stercoralis
    • Characteristics
      • Also known as a threadworm
      • Type of nematode (roundworm) parasite
    • Transmission
      • Found in soil contaminated with human feces
        • Larvae invade the skin of barefoot walkers
        • Usually in tropics of SE Asia
    • Pathogenesis and Presentation: Strongyloidiasis
      • Skin irritation at site of skin invasion
        • Urticaria and swelling 
      • After entering the foot, migrate via blood to the lungs
        • Early pneumonitis
          • Pulmonary signs of worm infection known as Loeffler syndrome
          • Presents with dry cough, bloody sputum, wheezing
      • Larvae migrate through trachea and are swallowed
        • GI symptoms
          • Intermittent abdominal cramps and diarrhea/constipation
        • Mature larvae may reinvade intestinal walls, causing autoinfection
      • Larvae may migrate subcutaneously from perianal region 
        • Raised pruritic skin streaks along lower trunk, thighs, buttocks
          • Also known as larva currens
      • Eosinophilia
        • Observed in >60% of cases
        • Non-specific; seen in many parasitic diseases
      • Immunodeficient patients prone to developing hyperinfection (multiorgan damage and sepsis)
    • Diagnosis
      • Stool microscopy (O&P)
        • Rhabditiform larvae seen in feces 
      • Serologic testing is gold-standard
        • Anti-strongyloides antibodies measured by ELISA
    • Treatment
      • Ivermectin
        • Bendazoles are second-line (less efficacious)