Toxoplasma gondii is a protozoan parasite that can infect almost all mammals and birds. Experts in zoonotic diseases estimate that about 50% of humans worldwide have this parasite!
This parasite is considered to be a significant concern because of its zoonotic potential. A “zoonotic” disease is one that can be transmitted from animals to humans. Toxoplasma gondii can lead to birth defects if pregnant women become infected as well as other serious medical problems.
T. gondii has a life cycle that involves two hosts. First, wild and domestic cats are the definitive host, meaning that the parasite reproduces and is shed into the environment only through felines. Cats originally become infected after eating a prey animal already infected with toxoplasma. An interesting note is that the majority of cats will only shed the oocysts (eggs) of the parasite in their feces for a short period of time (8-21 days) during their life. However, cats that are under-nourished, infected with other parasites or under stress can reshed these oocysts at later times. This makes the feral cat population a concern for the spread of this parasite. Other mammals, including humans, and birds can become infected from ingesting the infective oocysts. The parasite then travels via blood and lymph vessels to other tissues, such as the brain and large muscles. Here, the parasite becomes a cyst and can also cause significant health problems for immune-compromised people or pregnant women.
Once shed into the environment, the oocysts require about 24 hours to become infective. This is important because daily cleaning of a cat’s litter box along with routine hand washing can greatly reduce any risk of contracting the parasite. There are other sources of infection. Although our domestic cats are often implicated in the transmission of toxoplasma, people can also become infected through eating inadequately washed raw fruits or vegetables, eating raw or undercooked meats and shellfish or even through contamination while working in the garden.
The important thing to remember is that although this is a very concerning disease, there are a few simple steps that cat owners can take to minimize the risk:
1) First, keeping cats indoors will greatly decrease the potential for infection. Since cats generally obtain the parasite through their carnivorous activities, indoor cats that don’t hunt are at lower risk.
2) Clean the litter box at least once daily. The oocyst of the parasite requires 24 hours to become infective so a daily scooping of the litter will decrease your risk AND also make your cat happier with a cleaner box!
3) Finally, follow good hygiene practices…wash your hands after handling your cat and/or the litter box and relegate the cleaning duties to someone who is generally healthy. Immunocompromised individuals (young children, the elderly, pregnant women, etc) will be at higher risk for contracting toxoplasma and develop more severe symptoms.
4) It is NOT necessary to get rid of your cat in most situations just because someone is pregnant. Ask one of our veterinarians for more details about toxo and steps you can take to help prevent the disease. They are well trained in understanding zoonotic diseases and will help you understand the risks.