What it is
Toxoplasma can infect almost any warm-blooded animal, but only in a cat does it multiply in a way that sheds its eggs, called oocysts, in the faeces. That lasts a short time, about a week or two after the first infection, and fresh faeces are not yet infectious: the oocysts need at least a day to mature.
Sometimes the parasite keeps multiplying in the tissues and causes illness: inflammation of the lungs, eyes, liver or nervous system. Kittens and cats with a weakened immune system are more at risk.
People can be infected through undercooked meat, unwashed vegetables, soil or cat faeces. In a pregnant woman the parasite can harm the unborn child, so if you are expecting, talk to your own doctor about the risk. In a litter box emptied every day the oocysts do not have time to become infectious.
Signs you may notice
An infected cat can look perfectly healthy. When it does fall ill it turns listless, runs a fever and stops eating, may struggle to breathe, and its eyes or the way it walks can change.
When to see a vet
Book a visit if your cat is listless, feverish and off its food, or its eyes have changed. If it struggles to breathe or has a seizure, a vet is needed immediately.
This is general information, not veterinary advice. For your own cat's health, tests and treatment, see a vet.