Toxocariasis Transmission and Prevention

Primary Sources of Infection

Humans become infected primarily through the oral route by accidental ingestion of embryonated Toxocara eggs present in contaminated soil, food, water, or from unwashed hands, according to the Journal of Infection 1

Contact with soil contaminated with Toxocara eggs from cat or dog feces can occur through touching mouth with hands after gardening, cleaning a cat's litter box, or touching anything that has come into contact with cat or dog feces, as reported in Pediatrics 2
Eating unwashed fruits or vegetables contaminated with soil can also lead to infection, as noted in Pediatrics 3 and Pediatrics 2

Visceral larva migrans presents with fever, eosinophilia, wheeze, cough, abdominal pain, and hepatosplenomegaly, according to Praxis Medical Insights 4
Ocular toxocariasis presents with visual changes, retinal granuloma, or uveitis, with eosinophilia being less common in isolated ocular disease, as reported in the Journal of Infection 1 and Praxis Medical Insights 5
Neurotoxocariasis can present with myelitis, encephalitis, or meningitis, as noted in the Journal of Infection 1 and Praxis Medical Insights 4

Washing fruits and vegetables thoroughly before consumption can help prevent infection, as recommended in Pediatrics 3 and Pediatrics 2

Approximately 78% of Toxocara infections in the United States are transmitted via oocysts from environmental contamination, not from direct animal contact, with children at highest risk due to closer soil contact, poor hand hygiene, and pica behavior 6

Daily litter box changes are recommended as Toxocara eggs require 1-5 days to become infectious after shedding, according to the American Academy of Pediatrics 7, 8
Thorough handwashing after any soil contact, gardening, or litter box handling is advised by the American Academy of Family Physicians 9, 7
Keeping cats indoors can prevent hunting and environmental contamination, as suggested by the American Academy of Pediatrics 7, 8
Feeding only commercial or well-cooked food, never raw meat, can reduce the risk of infection, according to the American Academy of Pediatrics 7, 8
Avoiding adopting stray cats or kittens under 1 year of age can reduce the risk of infection, as they have higher infection rates, advised by the American Academy of Family Physicians 9
For immunocompromised individuals, such as HIV-infected persons, avoiding contact with cat feces and maintaining strict hand hygiene is crucial, recommended by the American Academy of Family Physicians and the Centers for Disease Control and Prevention 9, 10

Ocular toxocariasis is a rare parasitic eye infection caused by the larvae of the roundworms Toxocara canis (dog) or Toxocara cati (cat); the larvae invade ocular tissues, most commonly affect children, and frequently result in permanent vision loss. 11

After accidental ingestion of embryonated Toxocara eggs, larvae migrate hematogenously to the eye, where they typically involve the uvea and retina. 11, 12