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Toxoplasma

Toxoplasma is a very common (worldwide) infection of cats and other animals, including people. Most cats, people, and other animals who are infected with Toxoplasma show no signs of infection and don’t require treatment. Illness from Toxo (called Toxoplasmosis) is more likely with a weakened immune system.[3] Pregnant woman often learn about Toxo because a new infection can be dangerous to the unborn child. However, getting Toxo from a cat is much less likely than other sources (unwashed fruits and vegetables, and uncooked meat). Screening by PCR (ClueJay Cat Stool Test Level 3) is a reliable way to search for Toxo actively being shed in the cat’s stool. However, blood testing (antibody levels) is a more reliable way to detect a less recent infection.

Toxoplasma can infect humans. Particular care should be taken by pregnant women and immune-suppressed people to avoid infection.

Companion Animal Parasite Council (CAPC)

All About Toxoplasma

What Is Toxoplasma?

Toxoplasma gondii is a common, worldwide infection of mammals and birds.[4] Cats get Toxo in one of three ways: as a kitten from their mother (rare), ingesting it from soil, water, or plant material contaminated with Toxo (from cat stool), or from eating a rodent or bird that is infected with Toxoplasma.

Toxo are protozoa (like Giardia, Tritrichomonas, and coccidia (Cystoisospora spp., Cryptosporidium)) and not “worms”, so are not susceptible to “deworming” medications used for roundworms, hookworms, tapeworms, or whipworms. With the naked eye you won’t ever see Toxo (or other coccidia) in your cat’s stool. This is because all stages of their life are microscopic.

Any warm-blooded animal is at risk of Toxo infection (e.g., dogs, people). Fortunately, illness after infection from Toxo in other pets is unlikely as their immune systems quickly suppress the Toxo activity, forcing the parasite to form dormant cysts in their body tissues. Only cats can shed Toxo in their stool after getting infected. Most cats who are infected with Toxoplasma show no signs of infection and do not require treatment. Illness from Toxo (called Toxoplasmosis) is more likely in cats with weakened immune systems.[3]

Humans are at risk of being infected with Toxo, but owning a cat infected with Toxo does not mean you or a family member will be infected. People are much more likely to get infected from eating raw meat (especially if not previously frozen for several days to kill the cysts)[6] and unwashed fruits and vegetables than by handling cat stool from the litterbox. People also get Toxo from accidently ingesting oocysts from gardening in soil contaminated with cat stool.[3,5] 

Toxo is most concerning for people with weakened immune systems (diabetes, chronic illness, HIV positive, during chemotherapy, etc.) and pregnant women. An unborn baby is at high risk if a pregnant woman becomes newly infected with Toxo during the pregnancy or becomes immune-suppressed during pregnancy after having suppressed the Toxo infection before the pregnancy.[5]

If you are pregnant, immune-compromised, or have any concern about the risk of Toxoplasmosis, please consult your healthcare professionals.

Searching for Toxo in stool samples is best done with microbe testing by PCR (ClueJay Cat Stool Test Level 3).

How Common Is Toxoplasma?

Toxoplasma is a common, worldwide infection of mammals and birds.[4] Based on blood antibody titers (which measure the immune response) Toxo appears to be very common in domestic cats in this country (ranging from 14% to 100% in studies).[4]

However, studies show that only about 1% of cats are shedding oocysts in their stool at any one time.[4] Oocysts are the egg-like form of Toxo that become infectious to other cats, people, and animals. Generally, a cat that is initially infected with Toxo will (within a few days to a few weeks) shed millions of microscopic oocysts in their stool but then only shed rarely or not at all after that.[7] This is because their immune system suppresses Toxo into a dormant state.

Human infection with Toxoplasma in the United States is approximately 11% in people between the ages of 6 and 49 years.[4] This isn’t all from cats though. Cats only shed Toxo for a short time, so the chance of infection from handling cats or their litterbox is small.[4] People are much more likely to get infected from eating raw meat and unwashed fruits and vegetables than by cleaning the litterbox. People also get it from accidently ingesting oocysts from gardening in soil contaminated with cat stool.[3] 

What Do Toxoplasma Look Like?

Toxoplasma are a type of protozoa called coccidia. There are three basic life stages of Toxoplasma gondii: oocysts (sporozoites), tachyzoites, and bradyzoites. All three forms are single-celled and too small to be seen by the naked eye. Two life stages can only be seen by biopsy and microscopy of the intestine (tachyzoites) or body tissues (bradyzoites). This is not a normal way to look for them unless a cat is very sick.

The oocyst (sporozoite) is the egg-like form of Toxo in the stool which can occasionally be seen during a fecal O&P (ova (egg) and parasite) test which is used to look for parasitic worms (roundworms, hookworms, tapeworms, and whipworms) and some other types of coccidia (Cystoisospora spp.) under the microscope. Even if suspected though, it is indistinguishable from other types of coccidia (Hammondia spp., Besnoitia spp.) so this is not a good way to screen for Toxo.[4]

Searching for Toxo in stool samples is best done using special test techniques (ClueJay Cat Stool Test Level 3).

What Symptoms Are Caused By Toxoplasma?

Most cats who are infected with Toxoplasma show no signs of infection and don’t require treatment. Illness from Toxo (called Toxoplasmosis) is more likely in cats with weakened immune systems, which can be caused by feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV).[3] Kittens that get Toxo in their mother’s womb or after birth are vulnerable to getting sick from the infection because their immune systems aren’t fully mature.[2] 

For cats or kittens that do get sick, signs include fever, loss of appetite, weight loss, and lethargy (drowsiness).[3,4] Other symptoms depend on where in the body the Toxo are causing damage. Toxo in the lungs can cause difficulty breathing and pneumonia, jaundice (yellowish mucus membranes) if damaging the liver, blindness if in the eyes, or imbalance, circling, behavioral changes, urine and stool accidents, or seizures if damaging the brain and spinal cord.[3,4]

Cats that have eye and nervous system damage are more likely to respond to treatment compared to cats with damage to the liver or lungs. It’s important to get treatment started as quickly as possible to improve the prognosis if any signs appear.[3]

How Do Cats Get Toxoplasma?

Cats get Toxoplasma gondii in one of three ways: as a kitten from their mother (rare), ingesting it from soil, water, or vegetation (grass, plants) contaminated with Toxo (from cat stool), or from eating a rodent or bird that is infected with Toxo.

Adult cats are most at risk of getting Toxo by hunting and ingesting small mammals or birds, eating uncooked or unprocessed meat (such as beef, pork, or lamb),[3] or through exposure to litterboxes, soil, or vegetation that is contaminated with the parasite. This puts cats that go outdoors and cats that hunt at much higher risk of infection than indoor cats.

Rarely, Toxo can be transmitted through the placenta from mother cat to her kittens, or to the nursing kittens in the milk.[4]

What Is the Toxoplasma Life Cycle?

Cats get Toxoplasma gondii in one of three ways: as a kitten from their mother, ingesting it from soil, water, or vegetation (grass, plants) contaminated with Toxo (from cat stool), or from eating a rodent or bird that is infected with Toxo. Like Cystoisospora coccidia, the life cycle is a little complex.

Toxoplasma gondii start their life as immature spores (called unsporulated oocysts) which are shed within the stool of an infected cat. A spore is a reproductive cell that is quite resilient and can survive for months to years indoors or outdoors.[3,4] Thus catteries, shelters, households, and outdoor environments (e.g., sand boxes) can stay contaminated with Toxo for long periods of time.

The oocysts (unsporulated) shed in the cat’s stool are not immediately infective to other cats, people, or animals. It takes between 1-5 days in the right conditions for these immature spores to sporulate and become infective.[3] “Infective” means that microscopic, motile sporozoites developed within the oocysts. After getting swallowed, these sporozoites get ‘hatched’ from the oocysts in the cat’s intestines. They then invade the cells of the intestines and lymph nodes to reproduce (as gamonts) and release the next generation of oocysts into the stool in a few weeks to months.[4] The activity of Toxo in the lining of the intestines damages or bursts cells. For cats with healthy immune systems though, signs typical of digestive upset (soft stools, diarrhea) are unlikely to be seen.

Toxoplasma doesn’t just stay in the lining of the intestines like other coccidia (Cystoisospora felis). Toxo sporozoites become rapidly multiplying tachyzoites which spread from the intestine to other parts of the cat. For most cats, their immune system forces the parasite into a resting (dormant) stage where they form cysts in muscles, liver, lungs, brain and spinal cord. These cysts contain slowly multiplying forms of Toxo called bradyzoites.[3] Most cats with these cysts live normal lives without the cysts ever causing noticeable health problems. However, cats with weakened immune systems that can’t suppress the tachyzoite or bradyzoite activity can become seriously ill.

Cats also get Toxo from eating other animals like rodents and birds. Other animals (including people) don’t shed oocysts in their stool like domestic and wild cats. Rather they get Toxo cysts in their tissues after having ingested oocysts (from the environment) or cysts (from eating other animals). These cysts develop in their body tissues and remain there, dormant for life. If that animal (e.g., rodent or bird) is eaten by an animal other than a cat, the Toxo emerges in the intestines and again forms dormant tissue cysts. If that animal instead is eaten by a cat, the Toxo emerges in the cat’s intestines with oocyst shedding within a few days that lasts for up to two weeks.[3,4]

Cat’s that are infected for the first time will soon shed millions of microscopic oocysts in their stools.[7] Cat stool containing infective oocysts is a source of infection, regardless of whether they are in litterboxes, gardens, or in sand boxes in which these cats have defecated.[3] The good news is that once this oocyst shedding episode is over and the cat’s immune response has suppressed the Toxo, it’s rare for the cat to re-shed oocysts and if they do it is infrequent and the number is much smaller.[7]

Kittens can get Toxo in their mother’s womb or after birth. They are particularly vulnerable to getting disease from the infection because their immune systems aren’t fully mature.[2] 

Can People Or Other Pets Get Toxoplasma?

Yes, both people and other pets can get infected with Toxoplasma.

In fact, any warm-blooded animal is at risk of Toxo infection (dogs included). Fortunately, illness from Toxo in other pets is unlikely as their immune systems quickly suppress the Toxo activity, forcing the parasite to form dormant cysts in their body tissues. Only cats can shed Toxo in their stool after getting infected.

Human infection with Toxoplasma in the United States is approximately 11% in people between the ages of 6 and 49 years.[4,5] This is not all from cats. Owning a cat infected with Toxo does not mean you or a family member will be infected. Cats only shed Toxo for a short time and it’s unlikely to be on their fur, so the chance of human infection from handling cats or their litterbox is small.[4] People are much more likely to get infected from eating raw meat (especially if not previously frozen for several days to kill the cysts)[6] and unwashed fruits and vegetables than by handling cat stool from the litterbox. People also get it from accidently ingesting oocysts from gardening in soil contaminated with cat stool.[3,5] 

Most healthy people that become infected don’t show any signs of illness, but some get flu-like symptoms that can last for weeks to months, before resolving.[5]  The healthy immune system usually suppresses Toxo activity, forcing them to form inactive (dormant) cysts in the body tissues where they may remain indefinitely.[5]

Toxo is most concerning for people with weakened immune systems (e.g., diabetes, chronic illness, HIV positive, during chemotherapy, etc.). Someone who was infected when healthy could get sick from a reactivation (relapse) of Toxo once immune-suppressed.[5] If newly infected with Toxo with immune suppression, severe symptoms are more likely.[5]

Toxoplasma is also worrisome for pregnant women. An unborn baby is expected to be protected by the mother’s immunity if the mother was infected before becoming pregnant.[5] An unborn baby is at high risk if a pregnant woman becomes newly infected with Toxo during the pregnancy or becomes immune-suppressed during pregnancy after having suppressed the Toxo infection before the pregnancy.[5] Damage to the baby is often worse if this happens earlier in pregnancy and can lead to miscarriage, stillbirth, abnormal head size, or to symptoms later in life like vision loss, mental disability, and seizures.[5] 

If you are pregnant, immune-compromised, or have any concern about the risk of Toxoplasmosis, please consult your healthcare professionals.

How Is Toxoplasma Prevented & Treated?

Preventing Toxoplasma from infecting other people or pets (cats, dogs, etc.) first and foremost is about hygiene. Toxo oocysts (eggs) take between 1-5 days (at least 24 hours) to become infective once passed in the cat’s stool, so daily removal of stool is simply the very best way to prevent exposure.[4]  While disinfecting is an effective way to kill some parasites, it does not work well for Toxo which is resistant to most disinfectants. Carefully cleaning with scalding water or steam is more effective at killing Toxo oocysts than disinfectants.[4] Dispose of cat stool in a way that prevents exposure to humans or other animals (e.g., landfill, incinerator).[4]

Prevent cats from becoming infected with Toxo by keeping cats indoors so they are not hunting and eating rodents or birds. Also feed only commercially prepared diets (not raw or undercooked meat or organ tissue to cats). These are common ways that cats ingest Toxo cysts that had been dormant in those animals now being eaten.

For people, washing hands with soap and water after exposure to cat litter, soil, sand, raw meat, or unwashed vegetables is the easiest way to avoid accidently ingesting Toxo oocysts. Also, cook meat completely to an internal temperature of 160 degrees Fahrenheit.[4] Additional information on human prevention can be found with the Centers for Disease Control (CDC).[5] People that are pregnant, immune-suppressed, or have any concern about the risk of Toxoplasmosis should consult with their healthcare professionals.

Treatment of cats for Toxo is not generally recommended unless signs of illness are likely from Toxo. Treating cats with Toxo symptoms may involve antibiotics, steroids (corticosteroids), and/or anti-parasiticides. These are all medications that require a veterinarian’s prescription.

Where Are Toxoplasma Medications Purchased?

ClueJay does not dispense or prescribe medications, and there are no FDA-approved medications in the U.S. for Toxoplasma treatment.[4] Treatment of cats for Toxo is not generally recommended unless signs of illness are likely from Toxo.

Treating cats with Toxo symptoms often involves an antibiotic called clindamycin, sometimes used in combination with steroids (corticosteroids) if there is inflammation of the eyes or nervous system.[3] A combination antibiotic, trimethoprim-sulphonamide can be used or alternatively, sulphonamide with pyrimethamine. Pyrimethamine is an anti-parasite medication that helps prevent parasites from growing and reproducing in the body. These are all medications that require a veterinarian’s prescription.

While it is always best to consult with a veterinarian prior to administering any medication, even an OTC version, it is especially true for off-label treatment of Toxoplasma. Always read the medication administration directions carefully and be on the lookout for potential side effects (like vomiting) when any medication is administered.

When/How is Cat Stool Tested For Toxoplasma?

Most of the time, Toxoplasma infections are not discovered unless veterinarians are searching for the cause of otherwise unexplained clinical signs. Toxo is common in cats but almost always, their healthy immune system suppresses Toxo and illness never develops.

Veterinarians recommend stool (fecal) testing kittens 2 to 4 times during their first year of life, and 1 to 2 times each year in adult cats (every 6 to 12 months). Veterinarians often call this stool health test a “Fecal O&P”, with the O&P meaning “ova (eggs) and parasites”. It includes special preparations of the stool sample and analysis using a microscope to look for roundworms, hookworms, tapeworms, whipworms, and some other types of coccidia (Cystoisospora spp.). The Toxo oocyst (sporozoite) is the egg-like form which can occasionally be seen with this stool test. Even if suspected though, they are indistinguishable from other types of coccidia (Hammondia spp., Besnoitia spp.) so this is not a good way to screen for Toxo.[4]  ClueJay Cat Stool Test Level 1, 2, and 3 include a stool O&P, but the O&P is unlikely to identify Toxo. However, they will get reported if suspected.

Stool testing by PCR (Polymerase Chain Reaction) is a better way to identify Toxo when a cat is actively shedding (producing) the oocysts. ClueJay Cat Stool Test Level 3 includes a Toxoplasma gondii by PCR assay along with PCR tests for other disease-causing protozoa, bacteria, and viruses found in cat intestines. These tests are designed to find the DNA of hard to find microbe pathogens.

Stool testing for Toxo has limitations though because the oocysts are rarely shed (usually only for 1-3 weeks after initial infection). That is a very narrow window to time to catch Toxo shedding, especially since it doesn’t usually cause signs like abnormal stool (soft stool or diarrhea). Cats that are showing symptoms of Toxoplasmosis also don’t tend to shed oocysts. 

If Toxoplasmosis is suspected as the cause of a cat’s symptoms, blood testing (antibody assays) can be a better way to determine past exposure to Toxo. Screen for Toxo in cats or kittens with fever, loss of appetite, weight loss, and lethargy (drowsiness).[3,4] Other symptoms depend on where in the body the Toxo are causing damage. Toxo in the lungs can cause difficulty breathing and pneumonia, jaundice (yellowish mucus membranes) if damaging the liver, blindness if in the eyes, or imbalance, circling, behavioral changes, urine and stool accidents, or seizures if damaging the brain and spinal cord.[3,4]

With ClueJay’s simple and intuitive testing solution from home, you can directly access this same professional reference lab testing for Toxo that veterinary professionals use commonly.

My Cat Tested Positive for Toxoplasma?

ClueJay Cat Stool Test Level 3 includes PCR assay tests for disease-causing bacteria, viruses, and protozoa found in cat intestines. One of those protozoa is a type of coccidia called Toxoplasmosis gondii. A positive test means Toxo DNA was detected in the stool. Most veterinarians then assume the cat was infected with Toxo (called Toxoplasmosis) and provide consultation on preventing other pets and people from getting infected during the shedding period(s). Cleaning the litterbox daily and separating the cat from other pets and at-risk (pregnant, immune-suppressed) household members during the shedding period (1-3 weeks) is recommended.

Cats that are actively shedding Toxo into their stools probably do not need treatment because this finding is not ususully associated with symptoms of illness. Most cats infected with Toxo will quickly suppress the parasite to form dormant (inactive) cysts and never get sick from it. Cats shed Toxo in there stool usually for just 1-3 weeks after being newly exposed, and then maybe only rarely at other times during their life.

A test result is not the same as a veterinarian’s diagnosis, so it’s always best to consult with a veterinarian about your cat’s test results to determine the safest and most effective treatment and prevention plan, and when to do follow-up stool tests.

ClueJay Cat Stool Test Levels 1, 2, and 3 include a reference lab stool O&P (fecal ova (eggs) and parasites) which screens for roundworms, hookworms, tapeworms, whipworms, and some types of coccidia. While Toxo may rarely be found in this type of stool preparation, this is not a reliable method because it looks like two other common protozoa: Hammondia spp. and Besnoitia spp. Therefore, microbe testing by PCR is used to reliably test for the presence of Toxo.  If this parasite was reported in this way, it’s best to consider this a “tentative finding of Toxoplasma” or “finding suspicious of Toxoplasma”. When this happens (Toxo suspected from stool O&P), it’s best to double-check with a Toxoplasma PCR test through your veterinarian or using ClueJay Cat Stool Test Level 3. Blood testing for Toxo may be recommended in some cases. Summary: the stool O&P is a great test to find worms and some types of coccidia, but not Toxoplasma.

Please consult your healthcare professionals if you are pregnant, immune-compromised, or have any concern about the risk of Toxoplasmosis.

My Cat Tested Negative for Toxoplasma?

ClueJay Cat Stool Test Level 3 includes PCR assay tests for disease-causing bacteria, viruses, and protozoa found in cat intestines. One of those protozoa is a type of coccidia called Toxoplasmosis gondii. A negative test means Toxo DNA was not detected in the stool. This is good news because no one wants their cat or kitten shedding Toxo, putting other pets and people at risk of infection.

Besides not shedding Toxo, a negative PCR test also means that either the cat is not infected with Toxoplasma or the cat is infected but just isn’t shedding Toxo in their stool. Since cats shed Toxo only rarely, it’s common to test a stool sample from an infected cat without any of this parasite’s DNA. This is called a “false negative” when the test result is negative but the cat is infected. 

Depending on their lifestyle, cats can remain at risk of Toxo exposure so a negative test result today doesn’t mean it couldn’t be positive later. If Toxoplasmosis is suspected as the cause of a cat’s symptoms, blood testing (antibody assays) is a better way to determine past exposure to Toxo. This is because cats sick from Toxo usually aren’t shedding Toxo in their stool during the illness.[4]

Sources

  1. Pets and Parasites, Toxoplasmosis
  2. Fetch by WebMD, Toxoplasmosis In Cats
  3. Cornell University College of Veterinary Medicine, Toxoplasmosis in Cats
  4. Companion Animal Parasite Council, Toxoplasma
  5. CDC, Parasites – Toxoplasmosis (Toxoplasma Infection)
  6. International Cat Care, Parasites – Toxoplasmosis And Cats

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