Toxocariasis

[Magaret]

Toxocariasis is infection caused by larvae of the roundworms Toxocara canis or Toxocara cati, which are parasites of animals.

Young children can acquire the infection when they eat soil contaminated with animal stool (feces) that contain the roundworm eggs.
The infection may cause fever, cough or wheezing, and an enlarged liver, and in some people, it may cause vision problems.
Doctors confirm the diagnosis by identifying antibodies to the roundworm in a sample of blood.
Regularly deworming dogs and cats can help prevent the infection.
Treatment is usually unnecessary but may include antiparasitic drugs and corticosteroids.

(See also Overview of Parasitic Infections.)
Toxocariasis occurs mainly in young children, who acquire Toxocara eggs by ingesting soil contaminated by the feces of dogs, cats, or other animals that carry the parasite. Sandboxes, where dogs and cats often defecate, pose a particular hazard for exposure to the eggs. Children frequently transfer the eggs from their hands to their mouth and may eat the contaminated sand. Occasionally, adults ingest eggs picked up from contaminated soil, other surfaces, or hands and become infected. Adults and children who have a craving for nonfoods, such as soil or clay (a condition called pica), are at particular risk.
After the eggs are swallowed, larvae hatch in the intestine. The larvae penetrate the intestinal wall and spread through the bloodstream. Almost any tissue of the body may be affected, but the liver and lungs are most commonly involved. The larvae can remain alive for many months, causing damage by moving through tissues and stimulating inflammation.
The larvae do not mature to adulthood in people, but they can remain alive in the body for many months. The larvae require another host for maturation: dogs, cats, or other animals.
Toxocara eggs may be ingested by other mammals, such as rabbits or sheep. In these animals, the eggs hatch into larvae, which penetrate the wall of the intestine and travel to various tissues where they form cysts. Rarely, people are infected by eating raw or undercooked meat from these animals.

[Gregory]

Infection of a human with the larvae of toxocara worms, causing illness and a risk of blindness from cyst formation in the eye.