Signs of infection in cats vary from being inapparent to weight loss, fever, diarrhea, pneumonia, encephalitis, and eye disease. Toxoplasmosis may be fatal in young kittens. Lyme Disease is caused by a bacteria carried by ticks and is rarely fatal, but causes serious illness in humans and dogs when not diagnosed and treated with antibiotics in its early stage. Cats who live in tick-infested areas may transport infected ticks from the field into households on their fur, increasing the risk of human exposure. When left untreated, the disease can cause skin ailments, paralysis, disorders of the nervous system, eye and ear problems, stomach disorders, cardiac symptoms, and arthritis of the large joints in people.
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.