Pregnancy Concerns for Cat Owners
By Katrina Quinn
Dangers about toxoplasmosis are a common issue for cat owners to be warned about during pregnancy with suggestions that they must rehome their pet. This is most often due to a misunderstanding about the infectious agent, Toxoplasma gondii (T. gondii). This article will describe some of the common ways that people come in contact with this agent, as well as steps that can be taken to prevent transmission and infection.
Few events are quite as exciting as when parents are expecting the arrival of a new bundle of joy in their lives. However, it is also common for this time to be a bit frightening. There is a great deal of information and advice available for new parents from a variety of resources, some of which can be contradictory about a particular topic. This is understandably confusing for anyone who is trying to make the best decision for their family. Fortunately for pet owners, veterinarians are trained to understand not only how to keep animals healthy, but also the best way to protect the people that interact with the animals. Your veterinarian can be a useful source of reliable information for you and your family.
T. gondii is a parasite which can infect many species of birds and mammals, including humans. It is the organism that causes toxoplasmosis, a widespread infection with inflammation caused by movement and replication of the organism in the tissues. Symptoms of infection are more severe in immunocompromised individuals, developing fetuses, and the elderly. Toxoplasmosis may cause lymphadenitis, encephalitis, pneumonitis, myocarditis, retinochoroiditis, fever, weight loss, or lethargy. The fetus of humans or other animals that are infected with T. gondii may develop neurologic disease, birth defects, stillbirth, and ocular disease.
As Toxoplasma grows and develops through its life cycle, it passes through three different stages. Each stage is transmitted to, and exists in, the host animal in different ways:
- Oocysts – Think of this stage like a seed outside. It is strong and difficult to destroy so that it can remain in the environment for months or even years. This stage is only produced by infected felids: domestic and wild cats. When these are shed through defecation, they must undergo a development process in the environment before they can become infective to other animals. This is called sporulation and it takes 1 to 5 days.
- Tachyzoites – This stage of the organism divides rapidly and spreads throughout the tissues in the body. It can infect all vertebrate animals and is able to pass through the placenta or mammary tissue and infect a developing fetus or newborn.
- Bradyzoites – This stage of the organism divides slowly and is dormant in the tissue of the host animal. It can be present in all warm-blooded vertebrate animals and can be destroyed by heat.
Animals become infected with T. gondii by ingestion of bradyzoites (when consuming tissue from mammals or birds) or by ingestion of oocysts from contaminated environments after they are shed by felids. Some common sources of exposure include:
- Gardening and yardwork
- Outdoor activities
- Unwashed fruits and vegetables
- Unpasteurized milk
- Undercooked meat
- Litter boxes that are cleaned less often than once a day
There are many easy and effective preventive measures that can be taken to protect yourself from infection with this organism. They include:
- Wash your hands well after being outdoors, working with soil, or handling raw meat or vegetables
- Freeze meat for several days before cooking
- Ensure that meat is cooked thoroughly to an internal temperature of 160°F
- Wash all cutting boards and knives with hot soapy water after each use
- Wash and/or peel all fruits and vegetables before eating them
- Avoid drinking untreated water, particularly when traveling in less developed countries
- Avoid raw milk
- Work closely with your veterinarian to ensure your cat is healthy
- Keep your cat indoors
- Do not allow your cat to hunt or to eat raw meat
When a cat becomes infected with this organism, it will shed the oocysts for only 1-3 weeks. This very short fraction of a cat’s overall lifespan would have to overlap with the time of the pregnancy in order to be a source of infection. This risk can be further reduced by:
- Not allowing the oocysts the 1-5 day opportunity to develop by cleaning boxes daily
- Have another household member to clean/change the litter boxes during the pregnancy period
- Proper hygiene, such as gloves, handwashing, and appropriate disinfectants are always important when working with animal waste
There is a test available to detect if a cat has been exposed to the organism in the past. Once a cat has been exposed, they are unlikely to shed the oocysts again during their life. Therefore, cats who test positive for antibodies to T. gondii should be considered unlikely to be infectious. Most cats that are shedding oocysts will not test positive during this time because it takes time to develop the immune response to the organism. Therefore, testing may not be a useful screening tool when making decisions about the risks involved. It may not be easy to tell if a cat is infected with T. gondii, so it is prudent to follow these precautions, regardless of the cat’s apparent health.
Lappin, Michael R. "Feline Toxoplasmosis raises health concerns for humans." DVM Newsmagazine, Boulevard 14.3 (2002): 40-43.
Lappin, Michael R., and W. David. "The real story on toxoplasmosis-what is the risk to you or your cat?."
Tuzio, Helen, et al. "Feline zoonoses guidelines from the American Association of Feline Practitioners." Journal of feline medicine and surgery 7.4 (2005): 243-274.
Website last accessed on 11 Oct 2016: https://www.capcvet.org/capc-recommendations/toxoplasma/