II. Epidemiology
- Incidence: 10,000 cases per year in United States
- Seroprevalence in United States: 13.9%
III. Pathophysiology
- Organism: Roundworms (Nematodes)
- Toxocara canis (dogs)
- Toxocara cati (cats)
- Transmission
- Dogs and cats ingest roundworm eggs in soil, feces
- Small mammals (rabbits) may act as intermediate hosts
- Female dogs or cats may transmit encysted larvae to puppies transplacentally or via Lactation
- Dog or cat feces contaminate soil
- Toxocara eggs incubate in feces for 2-4 weeks until larvae infectious
- Young children (age <3 years)
- Eat contaminated soil (Geophagia)
- Common in playgrounds and sandboxes (contamination rates are as high as 40%)
- Older children and adults
- Ingest undercooked meat or raw liver infected with Toxocara larvae
- Dogs and cats ingest roundworm eggs in soil, feces
- Infection
- Clinical manifestations are dependent on multiple factors
- Parasite load
- Host immune response
- Larvae migration path
IV. Findings: Toxocariasis Presentations
- Visceral Toxocariasis (children ages 2-4 years old)
- Inflammatory response in liver, heart, lungs, brain, Muscle
- Ocular Toxocariasis
- Covert Toxocariasis (most common)
- Asymptomatic or mild symptoms
V. Symptoms: Visceral Toxocariasis (children ages 2-4 years old)
- Constitutional
- Pulmonary
- Gastrointestinal
- Neurologic
- Meningoencephalitis
- Skin
VI. Complications
- Epilepsy may develop in toddlers
- Ocular Larva Migrans (Endophthalmitis)
VII. Differential Diagnosis
- Hepatitis
- Encephalitis
- Viral myalgia
- Epilepsy
- Pneumonia
- Trichinosis
- Eosinophilic Leukemia
- Periarteritis Nodosa
VIII. Labs
-
Complete Blood Count
- Anemia
- Leukocytosis with >20% Eosinophilia
-
Serology for Toxocara Antibody
- Does not distinguish acute versus prior infection
- Other findings/tests
IX. Course
- Typically a self limited course in most cases
- Generally benign
X. Management
- Indications
- Most cases are treated
- Severe cardiac or pulmonary disease
- Neurologic involvement
- Preparations
- Albendazole (Albenza)
- Dose: 7.5 mg/kg up to 400 mg orally twice daily for 5 days
- Preferred agent in United States
- Mebendazole (Vermox)
- Dose: 100-200 bid for 5 days
- Not available as of 2012 (use Albendazole instead)
- Diethylcarbamazine (Hetrazan)
- Dose: 6 mg/kg/day divided tid for 7-10 days
- Has been used outside U.S. to treat Visceral Larva Migrans
- Albendazole (Albenza)
- Adjunctive
- Corticosteroids are indicated if inflammation present (especially with Ocular Larva Migrans)
XI. Prevention
- Careful child supervision
- Prevent soil ingestion
- Encourage Hand Washing
- Regular worming of cats and dogs
- Clean up after pets
- Cover sandbox between use
- Cook liver and other organ meats well before eating
XII. Resources
- CDC Toxocariasis