Most cats infected with the Toxoplasma parasite never look sick, and you can't catch it by petting your cat. In the US, people are more likely to pick up the parasite from undercooked meat or unwashed produce than from a litter box. Two habits cover the main ways a cat could pass it on: scoop the litter box every day, and keep your cat indoors on cooked or commercial food.
That matters most if someone in your home is pregnant or has a weakened immune system. Those people need a few extra precautions, which we list below. They do not need to give up the cat.
What Is Toxoplasmosis in Cats?
Toxoplasmosis is an infection with Toxoplasma gondii, a one-celled parasite found worldwide. It can infect almost any warm-blooded animal, including birds, dogs and people. Cats are special in one way: they are the parasite's definitive host, the only animals in which it reproduces sexually and makes eggs (called oocysts) that pass out in the poop.
Infection is common, illness is not. According to International Cat Care, somewhere between 20% and 60% of cats are infected at some point, depending on their lifestyle, but very few ever show signs. Outdoor cats that hunt and cats fed raw meat are the most likely to be infected.
Toxoplasma gondii oocysts in a fresh fecal smear from a cat, confirmed by PCR. Under the microscope these eggs look like the eggs of a couple of related parasites, which is why a lab DNA test was needed to name them. Sent by a follower on our Facebook page.
How Cats Catch and Shed Toxoplasma: The Life Cycle in Plain Words
The life cycle sounds complicated, but the part that matters for your household comes down to timing.
- A cat swallows the parasite. Usually by eating an infected mouse, bird or other small animal, or raw or undercooked meat. It can also swallow ripe eggs from soil, water or plants.
- The parasite multiplies in the cat's gut. About 3 to 10 days after eating infected prey or meat, the cat starts passing eggs in its poop, often millions of them.
- The cat sheds eggs for a short window. The CDC puts it at about 1 to 3 weeks. Most cats then become immune and shed eggs only once in their life. Cats with a weakened immune system are the exception and can shed again.
- Fresh eggs are not infective yet. They need 1 to 5 days outside the cat, and never less than about 24 hours, to ripen (sporulate) into an infective stage. This is the step daily scooping takes advantage of.
- Ripe eggs last a long time. They can survive in soil, sand and water for months, and well over a year in some conditions.
- Other animals swallow the eggs. Rodents, birds, livestock and people become intermediate hosts. In them the parasite spreads as a fast-multiplying form (tachyzoites) until the immune system pushes it into resting cysts (bradyzoites) in muscle and the brain. Those cysts can stay for life.
- A cat eats that animal or its meat, and the cycle starts again.
So the eggs in your cat's litter box are only a risk if they sit there long enough to ripen. Scoop every day and you remove them first. The CDC puts it plainly: the parasite does not become infectious until 1 to 5 days after a cat sheds it, so cleaning the box daily removes the feces before they become infectious.
Shedding is also rarer than people assume. At any one time, only about 1% of US cats are passing eggs, according to the Companion Animal Parasite Council (CAPC).
Signs of Toxoplasmosis in Cats
Most infected cats show no signs at all. A healthy adult cat's immune system usually shuts the parasite down into resting cysts before it does damage.
Illness is more likely when the immune system can't keep up: in young kittens, in cats with feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), and in cats whose immune system is suppressed, for example by chemotherapy. When toxoplasmosis does cause disease, the signs depend on where the parasite settles.
- General: fever, loss of appetite, tiredness (lethargy), weight loss. These are the most common signs.
- Lungs: pneumonia, with breathing that gets harder over time.
- Liver: yellow gums, skin or whites of the eyes (jaundice).
- Eyes: inflammation inside the eye (uveitis), pupils of different or unusual size, blindness.
- Brain and nerves: wobbliness, sensitivity to touch, personality changes, circling, head pressing, ear twitching, trouble chewing or swallowing, seizures, and loss of bladder or bowel control.
- Less common: swollen lymph nodes, vomiting, diarrhea, muscle pain.
Kittens infected before birth are the most vulnerable. Some are stillborn or die before weaning.
One reassuring detail: a cat that is sick with toxoplasmosis is usually not shedding eggs. The illness comes from the parasite spreading through the body, not from the gut stage that produces eggs.
When to Call Your Vet
Every one of these signs has other possible causes, and any of them deserves a vet visit.
- Go now: trouble breathing, a seizure, or sudden blindness.
- Call your vet today: fever, not eating, lethargy, weight loss, yellow gums or eyes, a red or cloudy eye, wobbliness or a change in behavior.
How Vets Diagnose Toxoplasmosis
Toxoplasmosis can be hard to pin down because its signs look like many other diseases. Your vet puts it together from your cat's history (outdoor access, hunting, raw food), a physical exam and lab tests. Expect blood and stool samples and sometimes urine. A cat with breathing signs may need chest X-rays; a cat with nervous system or eye signs may need further tests.
What the Blood Test Can and Can't Tell You
The most useful blood test looks for two kinds of antibodies the immune system makes against Toxoplasma: IgM, which shows up early in an infection, and IgG, which comes later and stays.
What the test finds | What it usually means for your cat |
|---|---|
IgM antibodies | A recent or active infection |
IgG antibodies, and the cat is healthy | Infected in the past, most likely immune and not shedding eggs now |
No antibodies | Never infected, so the cat could still catch it and shed eggs for a short time |
What it can't tell you is whether a cat is shedding eggs right now. Most cats that are shedding haven't made antibodies yet. A routine stool check under the microscope isn't reliable either, because Toxoplasma eggs look like those of other parasites. A lab DNA (PCR) test on a stool sample can detect shedding, but shedding lasts only a short time and sick cats are usually not shedding, so a negative result says little. A definite diagnosis of the illness needs a tissue sample examined under the microscope.
Treatment and Outlook
Many infected cats never need treatment, because they never get sick. When a cat is ill, your veterinarian chooses the medicine. Treatment usually means:
- An antibiotic your vet prescribes, usually for several weeks, that acts against the parasite.
- Anti-inflammatory medicine when the eyes or brain are badly inflamed.
- Medicine to control seizures, if they happen.
- Supportive care, such as fluids or feeding support for a cat that is dehydrated or too weak to eat.
Cats often start to improve within a few days of starting treatment, and your vet will want to know if yours doesn't. The outlook depends on which organs are affected and how quickly treatment starts. Cats with eye or nervous system signs tend to recover more slowly but often do well if they improve early. When the liver or lungs are badly affected, the outlook is usually poor, which is one more reason to see your vet early.
There is no vaccine against toxoplasmosis for cats or people.
How to Keep Your Cat From Getting Toxoplasmosis
Prevention for your cat is mostly about what it eats. Cornell's Feline Health Center notes that indoor cats that don't hunt or eat raw meat are unlikely to be infected.
- Keep your cat indoors so it can't hunt mice and birds. Our guide to indoor vs outdoor cats covers the tradeoffs, and the video below has ideas for keeping indoor cats happy.
- Feed commercial dry or canned food or well-cooked food. Cooking kills the cysts in meat.
- Skip raw meat, raw organs, bones and unpasteurized milk.
- Keep cats out of barns and buildings that house food animals, and out of food storage areas.
Can People Catch Toxoplasmosis From Cats?
They can, but cats are a smaller part of the picture than most people think. The CDC estimates that over 40 million people in the US are infected with the parasite. Most healthy people never have symptoms. Those who do usually have a flu-like illness with swollen lymph nodes and aching muscles.
How people actually get it, according to the CDC:
- Eating undercooked meat, especially pork, lamb and venison, or raw shellfish.
- Touching raw meat and then their mouth, or using knives and boards that touched raw meat.
- Eating unwashed fruit and vegetables, or getting garden soil on their hands.
- Swallowing eggs from cat poop: an unwashed hand after cleaning a litter box, soil or sand.
- Drinking untreated water or unpasteurized goat's milk.
- From mother to baby during pregnancy, and rarely through an organ transplant or blood transfusion.
Cornell's Feline Health Center says that in the US, people are much more likely to be infected by eating raw meat and unwashed fruits and vegetables than by handling cat feces. International Cat Care agrees that most people catch it in other ways, especially from undercooked meat, and that owning a cat doesn't in itself raise your risk. Stroking your cat won't spread it, because the eggs aren't found on the coat, and bites and scratches are an unlikely route. Toxoplasmosis isn't the only infection people can pick up from cats; our guide to cat scratch fever covers another one.
Who Needs to Be Careful
The CDC names two groups for whom toxoplasmosis can be serious:
- Pregnant women (and their babies). The risk is to the baby, and only when the mother is infected for the first time during pregnancy or just before it. The mother may have no symptoms. Most infected babies look healthy at birth, but some develop serious problems later, such as blindness or mental disability.
- People with a weakened immune system, such as people with HIV, people on certain types of chemotherapy and people who recently had an organ transplant. In them, toxoplasmosis can cause headache, confusion, poor coordination, nausea or vomiting, fever and seizures.
If you're in either group, the habits below handle the cat side of things.
Pregnant or Immunocompromised? Keep the Cat, Change These Habits
Pregnant women and people with weakened immunity used to be told to avoid cats. According to Cornell, the CDC now says that isn't necessary. These habits, mostly from the CDC's own advice with a few additions from CAPC and International Cat Care, cover the real risks.
In the litter box
- Have someone else scoop the litter box, every day. If no one else can, wear disposable gloves and wash your hands with soap and water afterwards.
- Bag used litter before it goes in the trash.
- Now and then, wash the box with detergent and scalding water, which kills the eggs. Most household disinfectants don't. Take care not to burn yourself.
In the kitchen
- Cook meat with a food thermometer: whole cuts (not poultry) to at least 145°F with a 3-minute rest, ground meat to 160°F, and all poultry to 165°F. Don't taste meat before it's cooked.
- Wash cutting boards, knives and counters with hot, soapy water after raw meat, and wash your hands.
- Rinse fruit and vegetables under running water.
- Skip unpasteurized goat's milk and raw oysters, mussels and clams, and avoid untreated water.
In the yard
- Wear gloves when gardening or handling soil or sand, then wash your hands.
- Cover sandboxes so outdoor cats can't use them as a litter box.
For your cat
- Keep your cat indoors and feed commercial dry or canned food, never raw or undercooked meat.
- Don't adopt or handle stray cats, especially kittens, and don't get a new cat while you're pregnant or immunocompromised. An adult cat that already lives with you, stays indoors and eats commercial food is a much smaller worry.
You might wonder whether to have your cat tested. Ask your vet what a test can tell you: a positive antibody result usually means your cat was infected in the past and is unlikely to shed eggs again, but it can't show whether a cat is shedding at this moment. The daily-scooping rule protects you either way.
For anything about your own health or your baby's, talk to your doctor. They can order a blood test to see whether you've been infected before and tell you which precautions matter most for you.
Originally written by Arais. Updated by the I Love Veterinary editorial team.
Sources
- CDC: About Toxoplasmosis
- CDC: Toxoplasmosis: Causes and How It Spreads
- CDC: Preventing Toxoplasmosis
- CDC: People at Increased Risk for Toxoplasmosis
- CDC DPDx: Toxoplasmosis (life cycle)
- Cornell Feline Health Center: Toxoplasmosis in Cats
- Merck Veterinary Manual: Toxoplasmosis in Cats (cat owners)
- Merck Veterinary Manual: Toxoplasmosis in Animals
- Companion Animal Parasite Council (CAPC): Toxoplasma gondii
- International Cat Care: Toxoplasmosis and Cats
- International Cat Care: Position Statement on Cats and Toxoplasmosis
- Hill's Pet Nutrition: Toxoplasmosis in Cats
This article is for general information and is not a substitute for advice from your veterinarian.
