Roundworms and People

Source: Center for Disease Control Updated on July 16, 2015
Roundworm

What is toxocariasis?

Toxocariasis is a zoonotic (animal to human) infection caused by the parasitic roundworms commonly found in the intestine of dogs (Toxocara canis) and cats (T. cati).

How serious is infection with Toxocara?

In most cases, Toxocara infections are not serious, and many people, especially adults infected by a small number of larvae (immature worms), may not notice any symptoms. The most severe cases are rare, but are more likely to occur in young children, who often play in dirt, or eat dirt (pica) contaminated by dog or cat stool.

How is toxocariasis spread?

The most common Toxocara parasite of concern to humans is T. canis, which puppies usually contract from the mother before birth or from her milk. The larvae mature rapidly in the puppy’s intestines; when the pup is 3 or 4 weeks old, they begin to produce large numbers of eggs that contaminate the environment through the animal’s stool. The eggs soon develop into infective larvae.

How can I get toxocariasis?

You or your children can become infected after accidentally ingesting (swallowing) infective Toxocara eggs in soil or other contaminated surfaces.

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