Toxoplasmosis

I've been seeing a lot of talk around cats and toxoplasmosis lately - especially when it comes to pregancy, so I wanted to do some research on the issue to learn more about pregnancy and cats with toxoplasmosis.

What is toxoplasmosis?

The Mayo Clinic says toxoplasmosis is an infection by a parasite called Toxoplasma gondii that can infect animals, including humans and most birds. It often doesn't cause any symptoms in humans, but that infants and people with weakened immune systems can get serious disease. Serious effects in immunocomprimised people could include eye disease that may cause blindness if untreated, or lung or brain disease. It also says that the parasite can be passed to an unborn baby during pregnancy, and that toxoplasmosis when pregnant can cause birth defects and miscarriage, so it is important to avoid becoming infected with toxoplasmosis while pregnant. 

So, how do cats come into the picture?

Toxoplasma gondii can only go through it's full life cycle in cats. Cats.com says that toxoplasma gondii can only produce eggs, or "oocycts" when hosted by a cat. Cat poop can contain immature eggs that then can infect humans. This is a big reason for the connection between pregnancy and cat litter box cleaning. Since cat poop can contain toxoplasma gondii eggs, it is often recommended that pregnant women not clean out a cats litter box in order to avoid coming into contact with the eggs. If you touch your mouth after cleaning the litter box of an infected cat, you could pick up the infection. I don't hear as much about gardening and pregnancy, but the parasite could also be present in soil that has cat feces in it, even if the cat poop has broken down and isn't visible. Since toxoplasma gondii can infect other animals and birds, it is also possible to become infected through uncooked or undercooked meat. 

And that is how cats become infected with toxoplasma gondii - through eating raw or undercooked meat. So, cats who hunt rodents or are fed raw meat are more likely to be infected. Commercial cat foods are ususually cooked, so that infection is less common in indoor cats who eat only cat food and cat treats. 

Once a cat is infected with toxoplasmosis, they often don't have any symptoms, so you may not know if your cat becomes infected. Immediately after infection, the toxo cat will have high numbers of oocysts in their feces for about 2 weeks. Cats.com says after that, the cat's immune system takes over and oocysts are no longer shed in their poop. 

These oocysts from toxo cats are not infectious to other animals immediately. There is a process called "sporulation" that has to happen before the oocysts can infect another animal, and this process takes 1 to 5 days. Once the sporulation has happened, oocysts can survive for many months and if ingested will hatch in the body of their new host. 

How common is toxoplasmosis in cats?

According to cats.com it toxoplasmosis is more common in tropical climates, but is present around the world. In fact they say it is estimated that around half of cats worldwide have been infected by toxoplasmosis! There is a test you can give your cat to see if they have antibodies for against toxoplasma gondii, which means they have been exposed to it. But, that only tells you that they have been infected at some point in their life. Since cats only shed the oocysts for the first 2 weeks after infection, a cat that tests positive for having antibodies for toxoplasma gondii may not have oocysts in their poop. The infection may well have happened more than 2 weeks before the test. While it's impossible to get an exact number Cats.com estimates that because of that 2 week window, the number of cats that could actively pass on oocysts is probably closer to 0.1%!

How common is toxoplasmosis in humans?

The ClevelandClinic.org says that worldwide up to 1 in 3 people have toxo! Cats.com says that does vary by region, with people in areas more likely to eat raw or undercooked meat having higher levels of exposure. They say that studies of anitibodies to toxo show that in the UK, 20-30% of people have been exposed to the parasite at some point.  In France and Germany, they say around 80% of the population has evidence of exposure! The CDC says in the United States, this figure is around 11%.

One theory actually says that one reason people love cats may be that they are infected by toxoplasma gondii! Since cats only shed oocycsts in their feces for around 2 weeks, the parasite needs to find it's way to another cat in order to continue to reproduce. In order to do that, toxoplasma gondii that has infected mice affects their behavior! Usually mice would be cautious around a cat, but toxo infection causes them to be more reckless and makes them attracted to cat urine! This puts that mouse into the path of cats, which could be very bad news for the mouse, but good news for the toxoplasma parasite that can now start their life cycle in a new host! The theory has it that toxoplasma gondii might also affect a human brain in the same way to make us attracted to cats! 

How common is toxoplasmosis in pregnancy?

Babycenter.com says the number of women who become infected with toxo during pregancy is relatively small. Also, not all women who become infected pass it on to their baby. The later into your pregancy, the more likely you are to pass it on to your unborn baby, but infection in the first trimester is the time when serious disease is most likely to develop for the baby. They say that out of 4 millions births in the U.S. there are around 300 to 4000 babies born with toxoplasmosis. Given the small window of time that cat poop contains oocysts, it makes sense that there would be a small number of infections during pregancy. 

If you are one of those people who have already been infected with toxoplasmosis and get pregnant, babycenter.com says your immunity will protect your unborn baby. The danger is the risk of new infections of toxo while pregnant. 

How do you reduce expsosure to toxoplasmosis?

Although the number of babies born with toxoplasmosis is small, you wouldn't want to take any chances, so it still makes sense to limit your exposure to toxoplasma gondii during pregancy, and the Mayo clinic gives us some advice on how to do that. 

Since toxo can be spread by meat, be sure to cook all meats thoroughly, including fish and shellfish. Toxoplasmosis can also be present in soil, so wash all vegetables and fruits before eating them as well. Also, be sure to wash utensils and cutting boards and don't forget to wash your hands too! 

Also, this might be hard for cat lovers, but stay away from stray cats or from introducing a new cat into your home during pregnancy since it is more likely that a cat who has been hunting outdoors will have been infected with toxo - possibly within the 2 week period where they would have oocycsts in their feces. 

For those of us with cats, you can help limit their exposure to toxoplasmosis by keeping them indoors so that they aren't hunting rodents and birds, and by feeding them only commercially prepared cat food. It is also a good idea to have someone clean out the litter box, just in case your cat has active oocysts. They say if this is not possible, to wear gloves and a mask while cleaning the litter box. Also, be sure to clean the litter box daily to try to eliminate cat poop before the sporulation process has taken place. And of course, wash your hands well! 

When it comes to toxoplasmosis and pregnancy, I'm not a doctor, and I would advise listening to medical advice. However, our cats are also part of the family, and I wouldn't recommend getting rid of your fur baby or babies! To me it sounds with some precautions like hand washing and limiting your contact with cat poop that is over a day old, your cat can remain part of the family throughout your preganancy! What do you think about pregnancy and toxoplasmosis? 

Cover photo by Esra Afşar on Unsplash