Toxoplasmosis has long been dreaded among pregnant women who live with cats. True, cats become carriers of the parasite ( Toxoplasma gondii ) from hunting and catching mice. The virus is shed in the cats' excrement, and pregnant women can contract it from handling litter box duties, and pass it on to the unborn baby with potential for birth defects and/or death of the foetus. Healthy adults very seldom are even aware that they have been exposed to toxoplasmosis, however immunocompromised people (HIV or transplant patients) are at risk.

However, if another household member will volunteer to keep the litter box clean, there is no need to throw out the cat in any of these situations.
Other sources of toxoplasmosis are eating undercooked meat and handling garden dirt that may contain the parasite. Therefore, pregnant women and others at risk, should always wear gloves when gardening, and make it a habit to cook meat thoroughly.

Other Zoonotic Diseases Implicating Mice

Hantavirus and toxoplasmosis are the better-known zoonoses¹ we can get from mice. Here are a few others which are rarer and probably not as wide-spread as the former two.

Yersinia Pestis The Plague, Black Death
Yes, this is more or less the same disease that wiped out twenty-five percent of the world's population from the 14th through the 17th centuries. The disease is transmitted to humans by:

• Contact with infected rodent fleas or rodents. Fleas may remain infected for months. Note: a protein secreted by the Yersinia is a coagulase that causes blood ingested by the flea to clot in the proventriculus. The bacillus proliferates in the proventriculus, and thousands of organisms are regurgitated by obstructed fleas and inoculated intradermally into the skin. This coagulase is inactive at high temperatures and is thought to explain the cessation of plague transmission during very hot weather. Pulmonary form spread by airborne or droplet infection. Human infections from non-rodent species usually result from direct contact with infected tissues, by scratch or bite injuries, and handling of infected animals. Several recent reports have detailed human plague associated with exposure to domestic cats. Exposure can be from inhalation of respiratory secretions of cats with pneumonic plague or by contaminating mucous membranes or skin wounds with secretins or exudates.
  UC Santa Barbara Zoonotic Diseases Study

Salmonella
By far, the most prevalent cause of salmonella in humans is by eating improperly prepared foods. However, it is thought that the house mouse may also be a host of the infection and may play a role in human and animal salmonellosis. Eight worldwide studies indicated a wide range of cats tested were culture-positive for Salmonella (0.6 - 27%).²

Rickettsialpox
Found most often on the East Coast of the U.S. in rodent-infested housing, and is transmitted by a mite carried by the common house mouse. The disease causes ulceration of the area surrounding the mite bite, fever, and a rash over the body and limbs. Rickettsialpox is treated with Tetracycline. The obvious conclusion is that, cute as they might be on T.V. and in the movies, mice are not our friends, nor are they particularly suitable for cat food. Besides the obvious dangers of cats living in large colonies (FIV, FIP, and FeLV), perhaps barn cats' steady diet of mice and other rodents contributes to their relatively short life span.

As for our surburbanite kitties, whether indoor-outdoor or indoor only, they would be better off without the addition of mice to their diets. If you feel compelled to let your cat have an occasional snack on mice, they are available online for sale and shipped frozen, usually in lots of 25 or 50. Sort of "mousesicles," if you will. Personally, I'll pass on that idea, and I didn't even allow my cats a vote.

¹Zoonoses: diseases transmissible from animals to humans. (For more information on terms used in this site, refer to the glossary. ²Humanitarian Resource Institute