Strongyloides stercoralis (threadworm)
⚠️ Disseminated strongyloidiasis occurs in immunosuppressed patients and can cause severe complications -
abdominal pain, septic shock, CNS involvement, and death if untreated. Early recognition and treatment are lifesaving.
📖 About
- Strongyloides stercoralis 🪱 - a soil-transmitted parasitic nematode infecting millions worldwide, especially in tropical & subtropical regions.
- Unique among helminths: can persist for decades due to its ability to autoinfect the host.
- In healthy hosts: often asymptomatic. In immunosuppressed (e.g. steroids, HTLV-1, transplant): risk of hyperinfection syndrome and dissemination.
🧬 Aetiology & Life Cycle
- Infective larvae penetrate skin (often via bare feet 👣).
- Travel through bloodstream ➝ lungs ➝ ascend airway ➝ swallowed ➝ mature in small intestine.
- Eggs hatch into larvae in bowel; some excreted, others re-enter host (autoinfection).
- Leads to chronic carriage - even after decades abroad.
🩺 Clinical Features
- Most asymptomatic, but may cause:
- 🌿 GI: abdominal pain, diarrhoea, anorexia, weight loss.
- 🫁 Respiratory: dry cough, wheeze, Loeffler’s syndrome (transient eosinophilic pneumonia).
- 🌐 Skin: urticarial rash (buttocks/waist), serpiginous “larva currens” tracks.
- ⚠️ Disseminated disease: sepsis, meningitis, respiratory failure - often fatal.
🔎 Investigations
- 📊 FBC: eosinophilia common (but absent in disseminated disease).
- 💩 Stool microscopy: insensitive (may miss up to 70% cases).
- 🧪 Serology (ELISA): high sensitivity/specificity ➝ useful for screening migrants from endemic areas.
- Consider multiple stool samples or culture techniques (Baermann, agar plate) for higher yield.
💊 Management
- ✅ Ivermectin: drug of choice (200 µg/kg daily for 1–2 days; longer in disseminated disease).
- 💊 Albendazole: 400 mg BD for 3 days (less effective, but an option if ivermectin unavailable).
- 📌 In disseminated disease: prolonged ivermectin courses ± combination with albendazole. Treat co-infections and support organ failure.
- 🔄 Screen and treat before starting steroids in patients from endemic regions.
💡 Teaching Pearls
- Think of strongyloides in any migrant with unexplained eosinophilia 🌍🩸.
- Hyperinfection syndrome is triggered by steroids, immunosuppression, or HTLV-1.
- Unlike most worms, strongyloides can persist for decades due to autoinfection.
- UK exam trick: eosinophilia + abdominal symptoms + history of living abroad = 💡 consider strongyloides.
📚 References
- CDC: Strongyloides (CDC)
- Grove DI. Strongyloidiasis: A clinical review. Clin Microbiol Rev. 1996.
- NICE CKS: Helminth infections.
