Simple Pulmonary Eosinophilia (Loffler Syndrome)


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  • Ascaris Lumbricoides or Suum (nematode roundworms): most common cause
  • Necator Americanus (a hookworm):
  • Ancylostoma Duodenale (a hookworm):
  • Ancylostoma Brazliense or Canium (dog and cat hookworms): infection through contact with fecally contaminated soil/ produces Cutneous Larva Migrans at site of entry (“Creeping eruption”: pruritic rash)/ do not mature to adult intestinal phase in humans, dying larvae reach lungs and cause inflammatory reaction/ most commonly cause Loffler’s but can also produce asthma
  • Entamoeba Histolytica: less common cause
  • Fasciola Hepatica: less common cause
  • Strongyloides Stercoralis (nematode roundworm): less common cause of Loffler’s


  • Pathogenesis for Ascaris (not the same for other parasites above): ingestion of Ascaris eggs -> hatch in intestine -> larvae penetrate mesenteric lymphatics and venules -> travel to pulmonary capillaries -> invade alveoli -> travel up bronchi -> swallowed and travel to intestine (where they mature)
  • Role of T-cell: pulmonary eosinophilia can be induced in mouse model by using Ascaris antigen extract (transit through circulation may not be necessary therefore to induce pulmonary eosinophilia)


  • Pathologic patterns: eosinophilic infiltration of bronchi and bronchioles
  • Larvae are not usually found in lungs


  • Sputum GS/Cult+Sens: no larvae or ova seen
  • CXR/Chest CT patterns:
    • Soft peripheral few cm densities or confluent infiltrates: usually bilateral
      • Usually migrate and disappear within 2-4 weeks
  • CBC: eosinophilia >10% (up to 30-70% in some cases)
  • Stool O+P: Ascaris ova are found in stool only after 6-12 weeks (therefore not useful in diagnosis of acute illness)


(may be asymptomatic)
(symptoms occur 10-16 days after initial ingestion of eggs or contact)

  • Dyspnea:
  • Wheezing:
  • Cough: dry or small mucoid sputum
  • Malaise:
  • Myalgias:
  • Anorexia:
  • Urticaria:
  • Fever:
  • Few crackles or wheezes on exam


  • Spontaneous resolution: symptoms resolve within days-weeks without treatment
  • Steroids: indicated for severe cases only
  • Piperazine (4g PO x1): indicated for Ascaris to kill worms


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