If your cat catches a mouse it is best to take the prize away from it. There are tiny, parasitic worms that can live in a cat's stomach. These worms cause frequent vomiting. Many people fear catching a protozoan disease, Toxoplasmosis, from cats. This disease can cause illness in the human, but more seriously, can cause birth defects in the unborn.
Toxoplasmosis is a common disease, sometimes spread through the feces of cats.
It is caused most often from eating raw or rare beef. Pregnant women and people with a depressed immune system should not touch the cat litter box. Other than that, there is no reason that these people have to avoid cats. Cats have a full inner-eyelid, or nictitating membrane. This inner-eyelid serves to help protect the eyes from dryness and damage.