What toxoplasmosis is
Toxoplasmosis is an infection caused by a microscopic parasite called Toxoplasma gondii. Many warm-blooded animals, including people, can become infected. Cats are special because they are the parasite’s definitive host, which means it can complete its reproductive cycle in the cat’s intestines and release eggs, called oocysts, in the cat’s feces.
For most healthy cats and people the infection causes few or no problems, but it can be serious in certain groups, particularly during pregnancy and in people with weakened immune systems.
How cats get it
Cats typically become infected by:
- Eating infected prey such as rodents or birds (see do cats eat mice)
- Eating raw or undercooked meat that contains the parasite
- Less commonly, ingesting oocysts from contaminated soil or water
- Kittens can occasionally be infected before birth or through milk
Do all cats carry it?
No. Most cats do not shed the parasite at any given time. After a first infection, a cat usually sheds oocysts in its feces for around one to two weeks, and then develops immunity, so shedding again is uncommon, although it can occur in some situations such as a weakened immune system. Cats that are strictly indoors and fed commercial or thoroughly cooked food are less likely to be exposed. A cat may carry the parasite in its tissues without ever shedding eggs while you own it.
Signs in cats
Most infected cats have no symptoms. When illness occurs, it is more likely in kittens and cats with weak immune systems. Signs can include:
- Lethargy and reduced appetite
- Fever
- Weight loss
- Breathing difficulty
- Jaundice (yellowing of the gums or skin)
- Eye problems or inflammation
- Neurological signs such as wobbliness or seizures
These signs have many causes, so a veterinarian must investigate.
Diagnosis and treatment in cats
Veterinarians may use blood tests, examination of the eyes, and other tests, and results can be tricky to interpret because many healthy cats have been exposed. Cats that are sick are usually treated with antibiotics prescribed by a vet along with supportive care. Do not medicate your cat on your own.
How people get infected
People are most commonly infected by:
- Accidentally swallowing oocysts, for example after handling cat feces or contaminated soil and not washing hands
- Eating undercooked or raw meat, particularly pork, lamb, and venison, that contains tissue cysts
- Eating unwashed fruit or vegetables, or drinking contaminated water
- Rarely, via organ transplant or from mother to baby in pregnancy
You do not catch toxoplasmosis by petting a cat, being scratched, or from being around a cat that is not shedding.
Effects on people
Many healthy people have no symptoms. Some get flu-like symptoms such as swollen lymph nodes, muscle aches, and fatigue that pass without treatment. Serious illness is more likely in people with weakened immune systems, who may experience problems affecting the brain, lungs, or eyes. The parasite can also affect the eyes in some otherwise healthy people. Doctors can test for infection and advise on treatment.
How likely is it from an indoor cat?
The risk from a cat that lives entirely indoors and does not hunt or eat raw meat is generally considered low. Oocysts need time after being passed, usually at least a day, before they become infectious, so cleaning the litter box daily further reduces risk. Food, soil, and undercooked meat are often considered more common sources than pet cats. If you are worried, speak to your doctor or veterinarian.
Reducing risk
- Scoop the litter box daily and wash your hands afterward.
- Wear disposable gloves when cleaning the box or gardening.
- Feed cats commercial food and avoid raw or undercooked meat.
- Keep cats indoors to prevent hunting.
- Cook meat thoroughly and wash cutting boards, utensils, and hands after handling raw meat.
- Wash fruits and vegetables well.
- Cover sandboxes and wear gloves in gardens where cats may defecate.
- Keep litter boxes away from food preparation areas.
If you are considering fostering, include these habits in your routine, as described in our guide to how to foster a cat.
Pregnancy and weakened immune systems
If you are pregnant, planning pregnancy, or have a weakened immune system, talk to your doctor or midwife about toxoplasmosis. Infection during pregnancy can harm a developing baby. A commonly given recommendation is to have someone else change the litter box if possible, and if not, to wear gloves and wash hands carefully. You generally do not need to give up your cat, but personalized medical advice is important.
What kills Toxoplasma?
Cooking meat to a safe internal temperature kills tissue cysts, and freezing meat may also reduce risk. Oocysts in the environment are tough and can survive for a long time in soil and water, and many common disinfectants do not reliably kill them. Prevention by hygiene, frequent litter changes, and hand washing is more practical than trying to disinfect. Ask your doctor or local health authority for specific guidance.
FAQ
How likely is it to get toxoplasmosis from an indoor cat?
Generally low, especially with daily litter cleaning and good handwashing, but risk is not zero.
What does cat toxoplasmosis do to humans?
Often nothing noticeable. Some people have flu-like symptoms, and it can be serious in pregnancy or when the immune system is weak.
Do all cats have the toxoplasmosis parasite?
No. Many cats have been exposed at some point, but only a short period of shedding follows a first infection.
Can allergies be confused with this infection?
They are different conditions. Read about whether you can develop a cat allergy if you have sneezing or itchy eyes.