What Was Covered

Toxocariasis

• Etiology: Toxocara canis (primary) and T. cati; nematode roundworms of dogs/cats; humans are dead-end hosts
• Epidemiology: 5% US seroprevalence; VLM in children 2–7 yr; OLM in older children/adolescents; soil/sandbox transmission via embryonated eggs
• Pathogenesis: Larvae migrate through liver, lungs, CNS, eye; eosinophilic granuloma formation; VLM and OLM are mutually exclusive
• Clinical syndromes: Covert (asymptomatic eosinophilia), VLM (fever/wheeze/hepatomegaly), Neurotoxocariasis (seizures/meningoencephalitis), OLM (unilateral visual loss/endophthalmitis)
• Diagnosis: ELISA for Toxocara antibodies (CDC); imaging for VLM; CT/fluorescein angiography for OLM; eosinophilia hallmark
• Differential: Retinoblastoma (for OLM), other eosinophilic parasitoses, CNS tumors
• Treatment: Albendazole 400 mg BID × 5 days; add corticosteroids for severe CNS/cardiac disease
• Prevention: Deworm pets, cover sandboxes, hand hygiene

Fascioliasis

• Etiology: Fasciola hepatica and F. gigantica (liver flukes/trematodes); sheep, cattle, goats as natural hosts
• Epidemiology: 2.4–2.6 million infected globally; Peru, Bolivia, Egypt highest burden; transmitted via metacercariae on watercress/aquatic plants
• Pathogenesis: Two phases — acute migratory (peritoneum → liver parenchyma, 3–5 months) and chronic biliary (adult flukes in bile ducts for years)
• Clinical signs: Acute: fever, eosinophilia, hepatomegaly, RUQ pain, urticaria, no jaundice; Chronic: biliary colic, cholangitis, obstruction, eosinophilia absent in 50%
• Diagnosis: Fas2 ELISA (acute, 92% sensitivity); Kato-Katz stool technique (chronic); CT track-like lesions; ERCP in biliary obstruction
• Differential: Acute cholecystitis, hepatic abscess, metastases; chronic: cholangiocarcinoma, other liver flukes
• Treatment: Triclabendazole 10 mg/kg × 2 days — praziquantel is ineffective (critical distinction)
• Prevention: Avoid raw watercress/aquatic plants; treat water; veterinary control of livestock; health education