Can kitty litter cause birth defects?

The question hints at one of the great dilemmas of cat loving women who want to have a child. There are millions of pages on the Internet about pregnancy and toxoplasmosis. It is the protozoan Toxoplasma gondii which causes the disease toxoplasmosis. The question refers to birth defects in a human newborn child.

T. gondii oocyst

The infection process

If a cat is infected with the protozoan toxoplasma gondii, the oocysts developing the cat’s intestines are passed out in their faeces. The faeces of an infected cat therefore can infect a person or another cat. A person can be infected if they come into direct contact with their cat’s faeces in the cat litter. However, it seems to me that it would need a person, the cat’s owner let’s say, to come into direct contact with their cat’s faeces with their hand and then to place their hand before washing it in or around their mouth which would allow them to ingest the oocysts. If you add that rare possibility to the fact that infective oocysts are only passed for a very short time after initial exposure by cats, the risk is low.

Toxoplasmosis cats pregnant women
Cat and pregant woman. Picture in public domain.

However, the downside is also very large potentially as it is clear that a woman who are infected can transmit toxoplasma in utero to their unborn offspring. The question then is whether the offspring is in jeopardy of contracting a harmful illness in utero?

My sources – a book and the Internet – tell me that a toxoplasmosis infection in a pregnant woman can result in abortion, stillbirth and the birth of babies with a central nervous system infection (Cat Owner’s Home Veterinary Handbook third edition, page 68).

In America, the Centres for Disease Control and Prevention (CDC) state that “occasionally, infected newborns have serious eye or brain damage at birth”. However, they make it clear that most infected infants do not have symptoms of birth but they warn that they can develop later in life.

2 women partially blinded by toxoplasmosis?
Were these women partially blinded by toxoplasmosis? Click on the image to read my opinion. Photos in public domain.

This information looks quite stark and scary to me and I can understand why women who are pregnant might consider relinquishing their domestic cat to a shelter. However, the advice is not to do it. The authors of the book (four veterinarians) that I mention state, “If you are pregnant, it is not necessary to get rid of your cat!”

They argue this because the risk is very low of getting an infection from your cat via cat litter and by far the majority of human cases of infection by the toxoplasma protozoan is from eating raw or undercooked meat particularly lamb or pork. Unpasteurised dairy products can also be a source of an infection. Those are the real risks and as I’m a cat lover I have to emphasise them.

However, the answer to the question in the title, “Can kitty litter cause birth defects?” is yes, if a rather tortuous and unlikely combination of events takes place. And it is possible through reasonable precautions to stop this chain of events taking effect and therefore the sensible advice is to take those precautions rather than relinquishing the family cat. You can also test your cat for toxoplasmosis.

Toxoplasma gondii cyst in mouse brain.
Toxoplasma gondii cyst in mouse brain.

Precautions et cetera

  • Wash fresh vegetables carefully because the oocysts can be in bits of soil attached to vegetables.
  • Wear gloves while gardening so that you avoid direct contact with soil which may be infected.
  • Pregnant women can be tested to determine if they have been exposed to this protozoan. They may have acquired immunity and therefore there is no risk to them.
  • Do your best to prevent your cat acquiring the disease by stopping them from roaming and hunting. This is another reason for keeping a domestic cat indoors full-time. If you allow your cat to go outside normally but are thinking of having a child then you might consider a change in policy to a full-time indoor cat before and during pregnancy as a possible means to minimise to near zero the risk.
  • Remove your cat’s stools daily from her litter box
  • When you dispose of your cat’s litter do it carefully to avoid it coming into contact with anybody else.
  • Litter boxes should be disinfected and cleaned properly using boiling water and a diluted bleach solution. This is necessary under the circumstances but usually it could be argued that if a person over-cleans the litter box it makes it less attractive to a domestic cat to use as a toilet.
  • If there is a sandbox or sandy area in the garden (backyard) it should be covered when not in use to prevent a cat using it as a toilet. I’m referring to either the family cat or a stray cat wandering into the garden.
  • If your cat eats raw meat then it should be stopped, I believe, and cooked instead maintaining a temperature of at least 150 degrees Fahrenheit or 65.5 degrees centigrade which is described as “medium well”.
  • After handling raw meat you should wash your hands with soap and water.
  • In addition, all kitchen services that have been used when preparing raw meat should be cleaned properly.

Protozoan parasites

Protozoan parasites are single cell animals which you can’t see with the naked eye. They can be seen under the microscope. They normally live in water. They can be identified under a microscope from a fresh stool specimen. You will be able to see the adult parasite or its oocysts.

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