Occasionally I am asked about the risk of pregnant women acquiring a parasite called Toxplasma gondii from their cat. I always think that cats get an undeserved bad reputation in this regard and I'd like to share information that might help lower the concern level from high anxiety to low-level caution. There is no question that IF a pregnant woman were to become infected, the risk to the fetus may be catastrophic. There is also significant risk for an immunocompromised human (AIDS or cancer patient) if he/she were to become infected for the first time. However, there would have to be a couple of coincidental timed events paired with poor hygiene habits for human infection to occur.
The cat is the definitive host, which means that a cat is necessary for the parasite to complete its life cycle. A cat eats raw meat containing Toxoplasma cysts (usually from chickens, sheep, goats or pigs) and will pass new eggs into its stool. After 1-2 days in the feces with exposure to air and moisture, the eggs will sporulate into the infective form for humans and other animals. This infective form, the sporocyst, can last months in the environment. The sporocyst is eaten by an intermediate host and travels into its muscle tissue. The life cycle comes full circle when a cat eats the raw meat of the intermediate host. A cat will pass the oocysts in its feces for only a 3 week period during the cat's lifetime, and usually about 3-10 days after eating the raw meat. Some cats can get sick with the intestinal form of Toxoplasma and have diarrhea. Very rarely, the cysts will migrate into the tissues of the cat in the same way it does to the intermediate host and the cat will suffer disease.
A human can get Toxoplasma sporocysts in one of three ways: ingestion of infected raw meat, oral contamination of infected cat feces after they have been sitting for 1-2 days, or a fetus can get infected through the mother's placenta. It is estimated that about 25% of North Americans have been exposed to this protozoal bug, and most have never experienced illness or have had mild flu/cold symptoms. There are some reasonable precautions that a pregnant woman or an immuno-compromised person can take to avoid exposure to Toxoplasma. The first is to not eat raw meat. It is wise to wash hands thoroughly after working in soil where cats may have defecated, or better yet, wear gloves. Of course, it is best if these persons can avoid cleaning cat litter boxes and have someone else in the household do that chore. But if that is not possible, the two easy and basic precautions to take are to wear dishwashing gloves and to scoop the poop each 24 hours before the infective sporocyst can even form. An excellent description can be found at the websites www.wormsandgermsblog.com and www.cdc.gov.
Dr. Mona S. Miller lives in Lafayette with her 4 year old son, yellow Labrador Retriever and grey cat. She has worked at Four Seasons Animal Hospital in Lafayette since moving here in 2001. She attended Cal as an undergrad, and received her DVM from U.C. Davis. She can be reached at Four Seasons, 938-7700, or by email to MonaSDVM@aol.com.
The cat is the definitive host, which means that a cat is necessary for the parasite to complete its life cycle. A cat eats raw meat containing Toxoplasma cysts (usually from chickens, sheep, goats or pigs) and will pass new eggs into its stool. After 1-2 days in the feces with exposure to air and moisture, the eggs will sporulate into the infective form for humans and other animals. This infective form, the sporocyst, can last months in the environment. The sporocyst is eaten by an intermediate host and travels into its muscle tissue. The life cycle comes full circle when a cat eats the raw meat of the intermediate host. A cat will pass the oocysts in its feces for only a 3 week period during the cat's lifetime, and usually about 3-10 days after eating the raw meat. Some cats can get sick with the intestinal form of Toxoplasma and have diarrhea. Very rarely, the cysts will migrate into the tissues of the cat in the same way it does to the intermediate host and the cat will suffer disease.
Lamorinda Weekly, Moraga CA