This article is from the Miscellaneous Cat Information FAQ, posted to rec.pets.cats newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
Toxoplasmosis is a disease that can be picked up by handling contaminated raw meat, or the feces produced after ingestion of such meat. It takes between 36 and 48 hours for the eggs shed in stools to reach the infective stage, so if you remove stools from the litter box every day, the chances are slim that you could contract toxoplasmosis. (Nomenclature: Toxoplasma gondii is the organism, toxoplasmosis the disease, and Toxoplasma is a protozoan.)
In theory, you can catch it by cleaning the litter box or by working in a garden used as a litter box. Most commonly, people catch it by handling raw meat or eating undercooked meat. Many cat-exposed people have had toxoplasmosis; the symptoms are similar to a mild cold.
The problem occurs when pregnant women contract toxoplasmosis. This will severely damage the fetus. Simple precautions will prevent this problem; unfortunately many doctors still recommend getting rid of cats when the woman is pregnant. A good idea is to get tested for toxoplasmosis *before* you get pregnant; once you've had it, you will not get it again.
You should note that there has yet to be a proven case of human toxoplasmosis contracted from a cat -- the most common sources of toxoplasmosis are the eating or preparing of contaminated raw meat.
To prevent human contraction of toxoplasmosis:
1. Cook any meat for you or your cat thoroughly.
2. Use care when handling raw meat.
3. Wear household gloves when handling litter.
4. Use disinfectant to clean the litter pan and surrounding area.
5. Change the cat litter often.
6. Keep children's sandpits covered when not in use.
7. Wear gardening gloves when working in the garden.
To be on the safe side, the litterbox and meat-chopping chores should go to someone else if you're pregnant.
An article in Cats Magazine (January, 1994) mentions toxo. To quote:
...transmission of the disease between cats and humans is highly unlikely. In fact, Karen D. Brooks, DVM, states that 'although the possibility of transmission from cats to humans exists, there has never been a documented case of prenatal toxoplasma infection in a human that was caused by a cat' (Veterinary Technician, September, 1992). Experts believe the real culprits of toxoplasmosis transmission are probably contaminated soil and infected meat.
The only way cats can transmit toxoplasmosis is through their feces, so simply having another family member change the litter box or wearing gloves and washing thoroughly afterward eliminates the risk. A pregnant woman should also wear gloves when gardening to avoid any contact with feces that may have been buried by outdoor cats. If other children in the family have a sandbox, it should be covered to prevent cats from using it as a litter box. It must be stressed that it is not possible to contract toxoplasmosis by petting, being licked by, or otherwise handling a cat.
If you have had toxoplasmosis in the past, you can't get it again. You can be tested to determine if you already have the antibodies, indicating that you have had the disease in the past and would not contract it again. Even if you do carry the antibodies, it would be wise to take all the same precautions, but that simple test could help ease your mind about the risk.
Re: toxoplasmosis: This is a short summary from the chapter on zoonoses (animal/human shared diseases) by Gary D. Nosworthy (pp. 577-582) in Nosworthy, G D (ed.) 1993. Feline Practice. JB Lippincott, Philadephia. ISBN 0 397 51204 X
Approximately 80% of the cats in the US show evidence of prior infection with Toxoplasma gondii, the causative organism. However, cats are able to release the stage (oocyst) that can infect humans only once during the cat's lifetime, and then, only for a maximum of two weeks. Oocysts remain infective for about 5 days maximum.
About 1/3 of the US population has been infected with T. gondii; once you are infected, you are immune. The only time that T. gondii causes more of a problem than a mild flu-ish illness is if you are immunosuppressed (AIDS, organ transplant recipient, etc.) or you become infected while you are pregnant. About 20-50% of the fetuses exposed to their mother's new T. gondii infection will become infected. Current US estimates of infection are that 1 of 1000 babies (0.1%) are infected. If you have a previous infection with T. gondii, you can handle infected materials with impunity during pregnancy... you and your baby are protected by your antibodies.
Cats are probably not the largest source of infection of T. gondii in the US: Having a pet cat, direct contact with cats around the house, working in a vet hospital do not increase the likelihood of contracting toxoplasmosis.
(ref: Reif, JS. 1980. Toxoplasmosis: Assessment of the role of cats in human infection. Compend. Contin. Educ. Pract. Vet. 2:810; Ganley, JP, Comstock, GW, 1980. Association of cats and toxoplasmosis, Am. J. Epidemiol. 111:238)
The best way to prevent the problems of toxoplasmosis contracted during pregnancy may be to contract it BEFORE pregnancy... The most common mode of transmission in the US is contact with uncooked or undercooked meat, esp. pork.
(ref: Jones, TC. 1983. Toxoplasmosis , p 438. IN Kay, D, Rose, LF, (eds.) Fundamentals of Internal Medicine. CV Mosby, St. Louis.)
Other modes of transmission in the US (much rarer) include transfusions of blood cells or platelets, or organ transplants.
There is also an experimental vaccine for T. gondii in cats. It is not commercially available.
Vets and physicians can have blood samples tested for T. gondii antibodies. T. gondii antibodies during pregnancy do not mean that the woman has just been infected... they probably reflect an old infection. Only rising antibody titers during pregnancy are a cause for concern.
Good cooking and handwashing practices will reduce the likelihood of infection of a previously uninfected pregnant woman to nearly nil.