Toxoplasmosis

Toxoplasmosis is caused by Toxoplasma gondii, a single-celled parasite. Cats are its only final host, which means the parasite can complete its life cycle only in a cat's gut. A cat usually picks it up by eating infected prey such as rodents and birds, or raw meat. Most infected cats never look ill. A few, especially kittens or cats with weak immunity, develop fever, breathing trouble, eye inflammation, or nervous-system signs, and need a vet.

A cat sheds eggs, called oocysts, in its stool only for a few weeks after its first infection. The eggs need a day or more outside the body to become infectious, so cleaning the litter box daily lowers the risk. People get toxoplasmosis more often from undercooked meat, unwashed produce or soil than from their cats.

The infection is a concern during pregnancy, since it can harm the unborn baby, and for people with weak immune systems. Anyone in these groups should ask their doctor for advice, let someone else clean the litter, or wear gloves and wash hands afterward. Keep cats indoors and avoid feeding them raw meat. Ask your vet about testing a sick cat, because a positive antibody test alone does not show active disease.