Toxoplasma gondii is a protozoan parasite. Related to the coccidian protozoa, it puts all warm-blooded animals at risk of Toxoplasma gondii infection. In this blog post, our South Florida vets share some facts about Toxoplasma gondii and how toxoplasmosis can affect your cat's eyes.
Toxoplasmosis
Toxoplasmosis is an infection caused by the single-celled parasite Toxoplasma gondii. This condition is often asymptomatic in cats and dogs, just as it is in humans. However, while the disease is not usually dangerous for people with healthy immune systems, it can easily become deadly in pregnant or immunocompromised patients.
The Toxoplasma Gondii Parasite Lifecycle
Cats are the singular definitive hosts for Toxoplasma gondii, while dogs and humans are intermediate hosts. Essentially, the parasite thrives within cats but will also live in canines or humans until they come across another suitable definitive host.
An infected kitty will pass feces with eggs inside it, and the parasite can spread to intermediate hosts if they consume the infected feces. If the feces is consumed by a member of the feline family, they will become infected and restart the lifecyle.
How Toxoplasma Gondii Spreads
Once a cat has shed the oocysts (eggs) and the infectious stage has begun, other animals and humans can pick the eggs up in a number of ways:
- Directly from Feline Feces – Remember to clean your cat's litter box daily. It takes at least 24 hours for eggs to become infectious. Remove the risk right away and wash your hands after cleaning the litter box.
- Ingesting Contaminated Meat – Pork, lamb, and venison are especially likely to be infected with Toxoplasma gondii. Always cook each piece of meat to the recommended internal temperature.
- Cover Sandboxes - Cats will use sandboxes as an outdoor litter box. If you have a sandbox on your property, be sure to cover it.
- Eating Contaminated Vegetables – Cats can release oocysts (eggs) in the garden, that can contaminate the soil of your fresh veggies. We highly recommend washing your veggies before eating them and peel them when possible. This isn't a likely way to contract Toxoplasmosis, but it is a possibility, so caution is advised.
- Drinking Contaminated Water – Today, contaminated water isn't as common in the United States. But, it's important to be aware of any emergency water advisory warnings in your area. If Toxoplasma gondii has contaminated the water, you don't want to consume unfiltered and unboiled tap water.
Symptoms of Toxoplasmosis
Most pets won't develop any symptoms of toxoplasmosis, but animals that have compromised immune systems could be at risk. Symptoms of a pet experiencing a dangerous case of Toxoplasmosis include diarrhea, and the signs of respiratory, liver, neurological disease, and eye discharge.
Additionally, the disease can trigger inflammation of the uvea, or pigmented part of the eye (uveitis), the retina, or the space between the lens and the cornea (the anterior chamber). Your vet may also notice the pupils are abnormally sized and not responding to light as they typically would. Toxoplasmosis can also cause cats to become blind.
When it comes to the nervous system, toxoplasmosis can cause heightened sensitivity to touch, lack of coordination, circling, head pressing, ear twitching, difficulty chewing and swallowing food, seizures, and loss of control over urination and defecation.
Diagnosis of Toxoplasmosis
Toxoplasmosis is typically diagnosed based on a cat's history, symptoms of illness, and laboratory test results.
A vet may measure two types of antibodies to T. gondii in the blood: igG and IgM. High levels of antibodies to T. gondii in a healthy cat indicate that the cat has been infected previously and is likely immune to the organism and not excreting eggs. These cats are no longer at risk of infecting other hosts.
On the other hand, high IgM antibody levels point to an active infection. If there are no T. gondii antibodies in a healthy cat, this suggests the cat is susceptible to infection and would shed eggs for up to two weeks after being infected.
The detection of eggs in feces is not a reliable diagnostic method, since they look similar to those of some other parasites. Additionally, cats can also shed eggs for only a short time and are often not shedding eggs when they are displaying signs of disease. To make a definitive diagnosis, your vet would need to conduct a microscopic examination of tissue samples to look for distinctive changes to the tissues and presence of tachyzoites (T. gondii in groups or clones).
How Toxoplasmosis Is Treated
Toxoplasmosis can be difficult to diagnose. While blood tests can be conducted for cats, the parasite can only be detected if your feline friend has been infected fairly recently. A positive test can't confirm if the parasite is still present, or if it is currently active. If your vet diagnoses your cat with toxoplasmosis, it is important for your cat to start treatment on antibiotics immediately.
If your cat is suffering from any eye issues related to this or other diseases, your primary veterinarian may refer you to our board-certified veterinary ophthalmologists (eye specialists) at Animal Eye Guys for treatment.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.