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. When the cat is ill, the inner-eyelid will frequently close partially, making it visible to the observer. You can tell a cat's mood by looking into its eyes. A frightened or excited cat will have large, round pupils. An angry cat will have narrow pupils.