Pregnant Women Should Not Handle Cat Litter

While doing some basic research for the 1993 Cryptosporidium Outbreak article, I ran across a fact based determination regarding why pregnant women should not handle cat litter boxes. The short answer is, due to the risk of toxoplasmosis.

Toxoplasmosis is an infection caused by a parasite called Toxoplasma gondii (T. gondii). This parasite is carried by cats and is present in its feces.

If a woman who has not previously been infected with T. gondii becomes infected while she is pregnant, there is a significant chance that the organism will produce severe neurological damage in the developing fetus.

Not only pregnant women and their unborn babies are at risk, but T. gondii is also a special risk to folks receiving cancer or transplant therapy or individuals that are positive for HIV.

Cats become infected by eating raw meat, usually mice, infected with T. gondii cysts. Cats will pass the oocysts in its feces. For approximately 3 to 15 days the cat will produce the oocyst-laden feces until purged and then cease being hazardous.

An oocyst is the thick-walled spore phase of certain microorganisms such as Cryptosporidium and Toxoplasma. Oocysts in cat feces are transferred to cat's litter boxes. Pregnant women should avoid handling cat litter boxes since the oocysts can cause eye, brain and other damage to the developing fetus.

T. gondii oocysts hatch, multiply in the human host, and may invade a variety of tissues. In most individuals this process is benign, but in pregnant women or in immunosuppressed individuals, the damage can be significant.

Let's not embark on a sky is falling approach, but appropriately assess the risk factors regarding your cat or neighboring cat:

• A household cat that may go outdoors and possibly eat raw meat is at a significant risk of being infected. The hunting may be sporadic, but it only takes one mouse.
• Outdoor cats that visit your garden will likely infect your crops.
• Indoor cats that are not exposed to rodents, not fed raw meat, or housed in a structure that rodents cannot access is obviously at a very low risk of infection.

The manner of transmission is from the animal contaminant to oral human ingestion. Therefore, it is very important that you do not stir up dust and/or aerosols from the cat litter and hands are thoroughly washed.

Note: It significantly lowers the risk of infection if the litter box is changed every day. The toxoplasma oocysts are not immediately infectious when they are shed, but will be with in 24-hours. It is highly recommended to assume that all cat feces are infected and that pregnant women NOT handle soiled cat litter.

It is also important to note that cat feces are NOT the only source of toxoplasmosis; in fact, most humans are infected by eating undercooked meat.

The best way for pregnant women and those that are immunocompromised to prevent infection is to:

• Avoid eating raw or undercooked meat.
• Peel and wash root crops thoroughly before eating them, or only grow vegetables that must be cooked.
• Assume that any cat's feces may carry toxoplasma oocysts.

Toxoplasmosis is considered to be the third leading cause of death attributed to food borne illness in the United States. More than 60 million folks carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness. Women who have never been exposed to T. gondii, but who become exposed while pregnant are those whose infants are at the greatest risk.

Resources:

1. http://www.iacuc.pitt.edu/occhealth/toxoplasma.htm

2. CDC

3. http://en.wikipedia.org/wiki/Oocyst