Epidemiology
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Etiology
- 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
Physiology
- 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)
Pathology
- Pathologic patterns: eosinophilic infiltration of bronchi and bronchioles
- Larvae are not usually found in lungs
Diagnosis
- 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
- Soft peripheral few cm densities or confluent infiltrates: usually bilateral
- 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)
Clinical
(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
Treatment
- 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
References
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