What is toxoplasmosis?

Discovered in 1908, toxoplasmosis is an intracellular parasitic infection caused by the protozoan known as toxoplasma gondii. It infects multiple of warm blooded including humans, livestock, birds etc., however cats are the definitive hosts to toxoplasma gondii. This means that the parasite is only able to sexually reproduce in cats (both wild & domesticated).

Most people have heard of toxoplasmosis due to the risks infections pose to pregnant women. If infection occurs during pregnancy it can cause abortion or congenital defects to the fetus. Toxoplasmosis infection in humans is extremely common & approximately 30 - 50% of the population have been exposed to it.

Oocysts are passed in the cat's faeces. They become infective after approximately 2-5 days. This is why it is so important to scoop your cat's litter tray daily.

What is a protozoa?

Protozoa are single celled organisms.

What are the symptoms of toxoplasmosis in cats?

Most cats don't show outward signs of infection. Although some cats will show clinical symptoms such as lethargy, loss of appetite, fever. Symptoms most often occur in kittens & young cats.

More severe symptoms may also include inflammation in the eye, pneumonia, hepatitis (inflammation of the liver), causing vomiting & diarrhoea,  enlarged lymph nodes.

What are the symptoms of toxoplasmosis in humans?

Enlarged lymph nodes, flu like symptoms, fever.

Severe toxoplasmosis in humans can sometimes occur & cause damage to the eyes, brain & other organs. This is more likely to happen in immunocompromised individuals such as people with HIV, organ transplant recipients & patients undergoing some forms of chemotherapy.

How is toxoplasmosis diagnosed?

Diagnosis usually involves a routine blood test. Your veterinarian could also examine a stool sample, although this would only offer a diagnosis if the cat was shedding oocysts at the time. Also, the oocysts could be mistaken for another parasitic infection, so a blood sample is the best & most accurate way to diagnose toxoplasmosis.

How does a cat become infected with toxoplasmosis?

The most common way a cat will become infected with toxoplasmosis is from eating the oocysts present in the tissue of chronically infected prey such as rodents & birds.

As with humans, it is also possible for cats to become infected from eating raw or undercooked meat.

How is toxoplasmosis treated?

Your veterinarian will prescribe a course of medication for your cat. Pyrimethamine, Clindamycin and Sulfadiazine.

What about pregnant women & toxoplasmosis?

If a pregnant woman hasn't had prior exposure to toxoplasmosis her immune system wouldn't have had the chance to build up a resistance to the disease. Therefore if she is exposed to it during pregnancy she is at risk of becoming infected & passing it on to her unborn fetus.

Having said that, there is a greater chance of her becoming infected from eating undercooked meat or improperly washed fruit & vegetables than from her cat.

Should a pregnant woman rehome her cat?

No, this isn't necessary. If you have a cat & become pregnant it is strongly recommended that you speak to your doctor, midwife or obstetrician about this, they may recommend a blood test which will check for antibodies to toxoplasmosis. If you have antibodies, you have been exposed to toxoplasma gondii at some stage in your life. This means your immune system has already built up a resistance therefore you are very unlikely to become re-infected. My own obstetrician tested me multiple times during my two pregnancies as I was negative & he wanted to ensure I remained negative.

What precautions can a pregnant woman take to avoid toxoplasmosis?

Cats aren't the only source of infection to humans. They can also become infected via improperly cooked meat, improperly washed vegetables, drinking untreated water (from a stream or river for example) & gardening.

• Avoid cleaning the litter trays, if this is not possible wear gloves & a mask. During my pregnancy I would also change & wash my clothes after cleaning litter trays.
• Ensure litter trays are scooped at least once a day.
• Ensure your meat is cooked thoroughly. This means it is no longer pink in the middle, the juices run clear & it has been cooked at 160F.
• Wash your hands after handling animals.
• Wear gloves in while gardening.
• Wash fruit & vegetables thoroughly before eating.
• Wash your hands after handling raw meat, fruit & vegetables.
• Wash your hands before eating.
• Don't let your cat(s) hunt.
• Cover sand boxes to prevent cats defecating in them.
• Don't drink unpasteurised milk.
• Thoroughly cleaning chopping boards & utensils. Use separate boards for fruit/vegetables & meat.
• Keep the litter tray away from the kitchen & other eating areas.

What about immunocompromised people:

Immunocompromised people can still enjoy living with their cat but must take precautions listed above.

If an immunocompromised person is looking to obtain a cat, it is worthwhile looking at an older (2 years or above).

Regularly treating your cat for parasitic infections such as worms & fleas.

Yearly physical exams for your cat are also important, including fecal tests & vaccinations.