Toxoplasmosis in Cats: Everything You Need to Know
Toxoplasmosis is one of the most discussed health concerns facing cats and cat parents. It is important to understand toxoplasmosis because it can be passed from cats to humans, leading to serious health consequences for immunocompromised people or pregnant women. Fortunately, there's no reason to panic as long as you equip yourself with some basic knowledge and take some precautions. In this article, we'll give you everything you need to know about toxoplasmosis to keep you and your kitty safe, and even answer the all-important question: can you flush cat litter?
Here at tuft + paw, we are cat experts. To write this article, we consulted veterinarian Dr. Megan Teiber and gathered information from respected health authorities, such as the CDC and Companion Animal Parasite Council (CAPC).
What is Toxoplasmosis?
Toxoplasmosis is an infectious disease caused by the single-celled parasite Toxoplasma gondii. This parasite has two types of hosts—definitive and intermediate. Cats are the definitive host where the parasite completes its life cycle and produces eggs. Any other animal (including humans) can be an intermediate host where T. gondii can fulfill other life stages, but cannot sexually reproduce.
T. gondii has three life stages:
- Oocysts — the infectious spores found in cat poop. These "eggs" are extremely hardy and can survive for over a year outside of a host.
- Tachyzoites — the fast-growing life stage that causes the toxoplasmosis disease.
- Bradyzoites — the slow-growing life stage that forms cysts in its host's tissue. These cysts remain in the host for life and usually lay dormant with few, if any, negative effects. Only found in mammals and birds.
T. gondii is found worldwide and holds the lofty title of being one of the most successful parasites on earth. The CDC suggests that 40 million people may be infected in the US alone—11% of the population! In developing countries that percentage can be even higher. The vast majority of infected people live with no symptoms.
Cats & Toxoplasmosis
Toxoplasmosis is far more likely to infect outdoor cats than indoor cats. There are two main ways that outdoor cats can become infected with T. gondii: 1) eating infected prey or 2) coming into contact with infected cat feces, often in outdoor sandboxes or soil beds. Indoor cats are unlikely to become infected as long as they are fed a commercial food diet. Being fed a raw diet increases the risk of an indoor cat contracting T. gondii through eating infected meat (usually pork, lamb, or venison).
Once infected, a cat will shed oocysts in their poop for 1-3 weeks. These oocysts take 1-5 days to become infectious, so scooping solid waste out of the litter box everyday significantly reduces the infection risk for your household. Shedding oocysts does not cause any illness in cats. Clinically ill cats with toxoplasmosis are usually immunocompromised, often from feline leukaemia virus (FeLV) or feline immundeficiency virus (FIV), and have vague symptoms such as fever and loss of appetite.
Veterinarian Dr. Megan Teiber had this to say about how toxoplasmosis is diagnosed and treated at the vet:
"Toxoplasmosis is not a very common problem to see in the vet clinic, because most cats do not show any symptoms. When cats do get sick, it is usually due to migration through the tissues during the tachyzoite stage of the disease. Symptoms depend on which body organs are affected and are often not very specific to toxo (fever, lethargy, inappetance, etc). Some cats will exhibit neurological signs such as seizures, discoordination, or abnormal behavior. You can also see jaundice and liver enzyme abnormalities if it is in the liver. If we see these signs and have ruled out other more common causes, we can run a toxo antibody test to aid in the diagnosis. The tests are not always straight-forward, so sometimes if we aren't entirely sure, we will empirically treat with clindamycin to see if the symptoms resolve. "
How Can Humans Contract Toxoplasmosis?
First of all, don't worry! You don't have to kick your fur-baby to the curb. According to the CAPC, cats do not carry T. gondii externally, so you are extremely unlikely to get infected from direct contact with your (or any) cat. According to Dr. Teiber, "cat parents should take precautions but not be overly concerned about toxoplasmosis." However, there are other possible routes of T. gondii infection for humans:
- Ingesting undercooked contaminated meat — especially pork, lamb, venison, and shellfish. This is the most common source of infection in humans. It's also possibly to accidentally ingest the parasite after handling contaminated meat and touching your mouth.
- Ingesting unwashed produce — produce that contacted contaminated soil.
- Drinking contaminated water — this is more common in developing countries.
- Ingesting contaminated cat poop — it's gross to think about, but after cleaning the litter box and contacting infected poop, you might unknowingly touch your mouth. Moral of the story: wash your hands!
- Ingesting contaminated soil — the hand-to-mouth pathway is always a risk when gardening or for kids playing in the dirt.
- Mother-to-child (congenital) transmission — if a pregnant woman contracts T. gondii for the first time during or shortly before pregnancy, she might pass the infection on to her baby. Mothers who have already contracted T. gondii have immunity and will transfer that immunity to their child.
- Receiving an infected transplanted organ or infected blood transfusion (rare)
Who Is At Risk From Toxoplasmosis?
According to the CDC, immunocompromised people and pregnant women are the ones at risk of more severe toxoplasmosis. Healthy adults usually show no symptoms of T. gondii infection because their immune system can suppress the tachyzoite production that causes illness.
Most people who feel any effects from toxoplasmosis will only experience flu-like symptoms such as aches, fatigue, and swollen lymph nodes. These symptoms can last over a month and can recur over time. The few who develop severe toxoplasmosis can suffer damage to the brain, eyes, lungs, and other organs. Thankfully, treatment is possible with medication.
Pregnancy and Toxoplasmosis
Pregnant mothers who are infected with T. gondii for the first time during pregnancy or a few months before pregnancy can pass the infection on to their baby. Most infected babies are born healthy, but may develop more serious health problems as they grow up (e.g. eye problems, motor skill development issues). Healthy infected mothers are unlikely to show symptoms of toxoplasmosis, and mothers who have been infected in the past will pass their immunity on to their baby. The NHS considers the chance of getting infected for the first time during pregnancy to be very small. For more peace of mind, women thinking of having a child can take a test to see if they are vulnerable to toxoplasmosis infection.
Ocular Toxoplasmosis
Ocular toxoplasmosis is a condition where T. gondii infects the inner eye tissue, and it can affect both healthy people and immunocompromised people. It is much more common in adults who have been infected congenitally than those infected after birth. Symptoms include worsening vision, blurriness, light sensitivity, redness, and floating specks in your field of vision. Medication exists for treating ocular toxoplasmosis.
How to Prevent Toxoplasmosis Infection
There is no vaccine for toxoplasmosis but, as Dr. Teiber states, "if some common-sense precautions are taken it is unlikely for people to acquire toxoplasmosis from their pet cats." Here's what cat parents can do to dramatically reduce their household's risk of infection. Note: Use hot soapy water when washing anything, whether it's dishes, utensils, or your hands.
- Cook whole cuts of meat to at least 145F, ground meat to 160F.
- Freeze fresh meat before cooking. Extreme temperatures kill T. gondii cysts.
- Don’t eat uncooked shellfish. Mussels, clams, and oysters are filter feeders which can collect oocysts from contaminated seawater.
- Rinse fresh produce to wash off potentially contaminated soil.
- Wash cooking and eating utensils after each use.
- Wear gloves when gardening and wash hands after handling soil.
- Scoop your cat's litter box daily and wash your hands. Oocysts don't become infectious for 1-5 days after being pooped out, so waste left in the litter box for longer than 24 hours is at greater risk of becoming infectious.
- If pregnant/immunocompromised, avoid changing the litter box. If you do, wear gloves and wash your hands.
- Keep cats indoors.
- Don’t adopt a new cat while pregnant or immunocompromised.
- Don’t feed your cat raw or undercooked meat.
- Cover outdoor litter boxes to prevent them from being used by other cats.
- If you want to take no chances, regularly clean the litter box with boiling water to kill any oocysts.
Can You Flush Cat Litter?
All this talk about toxoplasmosis leads us to a pivotal questions for cat parents: can you flush cat litter down the toilet? The answer is: it depends. Toxoplasmosis oocysts are extremely tough and cannot be killed by conventional sewage treatment, so whether you can flush cat litter depends on the risk of your cat being infected. Here are some general rules to follow.
Yes, you can flush cat litter if:
- Your cat stays indoors and is fed a commercial food diet.
- You live in a region where flushing cat litter is legal. Check your municipal guidelines.
- Your cat litter explicitly states that it is flushable.
No, you shouldn't flush cat litter if:
- Your cat spends time outdoors.
- Your cat lives indoors and raw/undercooked meat is part of their diet. This includes table scraps like medium rare steaks or raw oysters.
- You live in California, or any region where flushing cat litter is illegal. Check your municipal guidelines.
- Your cat litter does not explicitly state that it is flushable.
Assuming you follow these guidelines, Dr. Teiber believes that "the risk from flushable litter is very low and unlikely to be a source of any toxoplasmosis outbreak."
Other Consequences of Toxoplasmosis
T. gondii can infect any animal and form cysts in any warm-blooded animal (mammals and birds), so precautions must be taken to limit the spread of oocysts in the environment. In fact, flushing cat litter is illegal in California because of a study that found toxoplasmosis infection in the local sea otter population. From 1998-2004, the researchers found that of 305 dead beached sea otters, 52% were infected with T. gondii. Of 257 live sea otters, 38% were infected. They concluded that toxoplasmosis was a major cause of mortality in southern sea otters and that the most likely source of infection was oocyst runoff from cat poop. As lovers of furry mammals, most cat parents (ourselves included!) are rightfully concerned by this information.
A more recent paper analyzed past studies of T. gondii in marine animals, and found that infection was most commonly detected in sea otters, whales, dolphins, seals, sea lions, shellfish, and manatees. Among all continents, North America had the highest rate of marine animal infection, suggesting a higher rate of infection in the soil and freshwater sources. This makes sense when you consider that the US has an estimated 76.5 million cats—more than any country in the world.
T. gondii oocysts can remain infective in seawater for up to two years, so it's essential that cat parents do their part to prevent oocysts from entering the marine environment in the first place. As we mentioned before, if you have an outdoor cat or feed your cat raw meat, do NOT flush cat poop or cat litter down the toilet. Instead, dispose of your litter in a secure plastic garbage bag. Indoor cats who eat a commercial diet are not at risk of infection, so flushing their litter and poop should be okay as long as it's legal in your city.
Conclusion
As a cat parent, toxoplasmosis can seem like a scary issue when you first hear about it, but there's really no need to panic. We hope this article has been helpful in demonstrating that toxoplasmosis can be largely prevented through simple best practices. By following the guidelines in this article, we can all help keep our four-legged and two-legged loved ones healthy and uninfected.
Okay, one last thing. On the topic of flushing litter, we should mention that we created our own formula called Really Great Cat Litter. It's made from recycled soybean fibre and it's totally natural, biodegradable, and of course, flushable! Check it out if that sounds up your alley, or you can take a peek at some of our educational resources below...
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