Pregnant women are the only people who need to worry about toxoplasmosis.

Toxoplasmosis is never a serious disease for the direct sufferer. It presents with mild cold-like symptoms. You can only get it once in life, and then you are immune to future exposure. Most people have already had it by adulthood, by doing one of the following:

Coming into contact with cat faeces
Coming into contact with dead wild birds (contact with the birds is how the cats get it)
Drinking raw milk
Working in soil without gloves (the bacteria are very commonly in soil)
Eating raw cheeses

You cannot catch toxoplasmosis from other people.

Toxoplasmosis is a risk to unborn children, though. IF a woman has never had toxoplasmosis, and gets it while she's pregnant, there is a high risk (not definite) that the baby will have severe birth defects.

For this reason all pregnant women are advised to avoid contact with cat litter or other ways of getting toxoplasmosis. Wear gloves when gardening, don't drink raw milk (advisable because of listeria risk, too), don't change the kitty litter.

A simple blood test can verify if a woman has already had toxoplasmosis.