A recent study published in Schizophrenia Research suggests that childhood cat ownership was more common in families in which a child became seriously mentally ill later in life. The link is believed to be the cat parasite Toxoplasma gondii (T.gondii), a protozoan. This isn’t the first time T.gondii has made the news. It was previously reported to hijack the brains of mice, making them fearless around cats and attracted to the smell of cat urine. From an evolutionary standpoint, this makes sense for the parasite. It makes it easier for an infected mouse to be caught and eaten by a cat, which is necessary for the parasite’s survival — as it can only replicate in the intestines of cats. Unfortunately, although it seems to control the brain of mice, it is unlikely to explain the “crazy cat lady” stereotype.
Toxoplasmosis Symptoms Can Develop if Your Immune System Is Weak
Like most cats, if you are infected with this parasite, you will probably never suffer any symptoms. According to the Centers for Disease Control, more than 60 million people in the United States carry the parasite, yet very few have symptoms. But you are at greater risk if you have a weakened immune system, such as young children or immunocompromised people — those with HIV/AIDS, who are on chemotherapy, or who are organ transplant recipients. If your immune system is weakened, you may develop flu-like illness or blindness, and you could even die from T.Gondii. If you are infected while pregnant, aninfection can lead to miscarriage or to brain damage that’s only noted later in the infant’s life.
Why Most Indoor-Only Cats Don’t Pose a Risk
Now, before you start thinking about putting your cat to the curb, remember that most indoor-only household cats do not pose a major risk of infection to humans, for two reasons:
- First, a cat must be exposed to the parasite, which usually occurs when they’re hunting wildlife — like infected birds and rodents.
- Second, an infected cat usually only sheds the parasite eggs, called oocysts, for up to three weeks after becoming infected.
Therefore, your indoor-only cat that you have had for years, even if it was previously infected with T.gondii, is highly unlikely to pass any more eggs in its feces, unless it becomes immunosuppressed from a disease or medication.
Furthermore, any eggs that are shed in cat feces take from one to five days to become infective once outside the cat. This means that cleaning the litter box one to two times a day and wearing gloves, or at least thoroughly washing your hands after doing so, will help avoid infection. It will also make your cat happy that it doesn’t have a dirty toilet. More likely sources of infection for you or your kids than your indoor-only cat are:
- Eating infected raw meats
- Handling soil, sand, vegetables, or fruits contaminated by infected stray-cat feces
How to Avoid Parasite Infection
I recommend wearing gloves when gardening and practicing good hygiene, such as washing your hands frequently and avoiding raw meats, to help prevent infection. Keep an eye on children and teach them not to place soil or sand in their mouths. Make sure they wash their hands after playing outside or with the cat — a very important way to avoid T.gondii infection. If you keep your cat indoors with a clean litter box (that is not accessible to kids) and practice good hygiene, you, your children, and your cat can continue to coexist safely in your home. If you are pregnant, it’s the perfect excuse to have someone else clean the litter box. And if your physician recommends getting rid of the indoor-only cat you have had for years, well, you may just consider getting rid of your physician instead.