Roundworms can reside in the intestinal tract of cats, other domestic animals, and wildlife. Cats can contract this parasite from eating infected wildlife, from ingesting eggs shed in feces, or larvae can be passed from a mother cat to her kittens via her milk in their first few weeks of life. The kittens can develop life-threatening disease as a result. Roundworms can be transmitted to people who accidentally ingest the parasite's eggs containing larvae, if children or adults ingest the eggs, the eggs hatch, and infective-stage larvae migrate through the liver, lungs, and other organs and tissues where they produce damage and induce allergic responses. Infection may leave children with permanent visual or neurological damage.
Roundworms can remain infective in the soil for a prolonged period.
Drugs are available to kill this parasite in cats and people. Hookworms, a type of roundworm that lives in a cat's digestive tract, can infect human skin, causing lesions. People acquire hookworm larvae through contact with wet sand. For example, children, electricians, plumbers, and other workers who crawl beneath raised buildings, are more susceptible than the general public, as are sunbathers. The larvae can remain alive and travel in the skin for up to several months.