Monday, November 29, 2010

On Toxoplasmosis

One of the big topics for pregnant women is Toxoplasmosis. We are warned to avoid our cats, or at the very least, their litter boxes. After years of working in pet hospitals and doing research on the topic for our expectant mother clients, I want to set the record straight.

This topic has utterly annoyed me since my first pregnancy, but now that I'm expecting my second child, I've come in contact with continued frustrations. Two stand out in my mind. The first, when I went into the doctor's office to have an early pregnancy consult with one of their nurses. I was already annoyed at the requirement for this meeting since I felt nothing of value was gained (I merely discussed my family's medical background and got an appointment for the doctor). In discussing my medical background, I was asked if I had pets, which I do - a cat and a dog. The nurse went on to ask if I knew about the litter box. Yes, of course I did, this wasn't my first rodeo. At least, that seemed to be the end of the discussion. A second incidence was with my mother-in-law who came to visit and insisted that she clean out the litter boxes while she was there since my husband was out of town.

Ok, so, why am I annoyed? Those don't sound bad, really. And all things considered, they aren't. I mean, c'mon, I got out of litter box duty. But in my mind, it's the same thing as using my pregnancy as an excuse to avoid housework, work, or activity in general, which is actually more harmful to me as a pregnant woman than doing those things in the first place, but I digress.

The thing is, our poor cats are being accused of transferring Toxoplama gondii (the protozoan that causes Toxoplasmosis) when there is a very high likelihood that they aren't. They are automatically cast as the villains in our pregnancies.

While most of us know that Toxoplasmosis is extremely bad in pregnancy - it can lead to birth defects or loss of the pregnancy - most of us don't know the whole story. We look up what could happen to us if we are infected and hear that we can get it from cleaning out the litter box and that is enough for us to steer clear of our feline friends. This is in error, however, and our cats should not be feared by us while we are pregnant. Let me explain. The information that is most often skipped over is how Toxoplamosis works in cats. That will give us an idea of what our risk really looks like.

Toxoplasmosis occurs in almost all warm blooded animals. The thing that makes cats different is that when they contract it, they can pass it in their feces - no other mammal does this. And this is why cats are called the definitive host for Toxoplasmosis and the reason we fear their litter boxes. There is more to the story though.

Cats typically get Toxoplama gondii by ingesting raw meat - like when they hunt rodents and birds or by coming in contact with contaminated soil or water. About a week after exposure, they begin passing the infective oocysts (kinda like eggs) in their stool - which, I'll be honest, can occur in large numbers. They pass the infective oocysts for up to two weeks. That's it. After that, the develop an immunity. They don't contract it again, they don't spread it. Here's another piece of the puzzle - the oocyst has to be outside the body for at least 24 hours before it truly becomes infective - a litter box that is cleaned out daily poses little to no risk.

So, what does that mean? Our villainous cats are not the big culprits. If your cat has been a happy indoor cat for years, your risk is virtually nil. An outdoor cat is more likely to be suspect, but again, if they are an older cat, most likely, they had it when they were very young and most likely no longer pose a risk.

Here's something else that they don't tell you - the most common way humans contract Toxoplasmosis is from eating raw meat or drinking raw unpasteurized milk. Not from cats. It is more likely to be found in sheep, goat, and pig as opposed to beef or poultry, but it is still possible. Just one more reason to ensure all meats are cooked thoroughly and your milk has been pasteurized. Also, fruits and vegetables should be cleaned thoroughly as contaminated soil on these foods can pose a risk - don't assume if you grew it yourself you are safe since neighborhood strays like to use gardens as litter boxes.

Where your cat is concerned, you can protect him or her by keeping your cat inside and not allowing your cat to hunt. Also, don't feed your cat raw meats or milk. Doing this will protect you as well. If you do have a cat that goes outside, that is a good reason to avoid the litter box or wear gloves when cleaning it out. Even better, if you have an outdoor cat, blood work can be run to check your cat's exposure. Any strays or new adoptions should be regarded cautiously since you don't know their history and exposure possibilities.

Above all, don't forget basic hygiene. A good hand washing is always recommended after handling raw foods or cleaning the litter box.

So, go on. Don't be afraid to give your cat a hug.

For more information check out: American Veterinary Medical Association and Cornell Feline Health Center


  1. While the above link is helpful, there are a few things I want to add. First, Toxoplasmosis is not commonly referred to as "Cat Scratch Disease." Cat Scratch Disease (or Cat Scratch Fever)is caused by another bacteria called Bartonella.

    Second, the link refers to cats as the primary host of Toxoplasma which is not true. A primary host would be the one that is the most common source of infection. Rather, cats are the DEFINITIVE host because they are the only species that passes it through their feces. This distinction is very important. The most common source of infection in humans is under-cooked meat.