Toxoplasmosis is a cat disease that can be transmitted to humans; although it can be very frightening, knowing the facts makes it possible to avoid it. Let's explore the most important information about toxoplasmosis in cats, what symptoms accompany it, how to treat it, and what risks cat toxoplasmosis during pregnancy can pose.
What is toxoplasmosis
Toxoplasmosis is a parasitic disease in cats in which the cat — and all other felines — serves as the definitive host; all other warm-blooded animals, including humans and dogs, are intermediate hosts. It is caused by an intracellular parasite called Toxoplasma gondii. There are three forms of toxoplasmosis: tachyzoites, bradyzoites, and tissue oocysts. Only in this last form is Toxoplasma found in cat faeces.
Contrary to what many people claim — including some doctors — the cat is not the sole source of toxoplasmosis. In fact, cats rank last among the routes of toxoplasmosis transmission. It is far more common to contract the disease from undercooked meat.
Toxoplasma gondii has two biological cycles: one takes place in the definitive host (the cat), and one in the intermediate host. The Toxoplasma cycle that occurs in cats is called the enteroepithelial biological cycle. This cycle begins when Toxoplasma gondii is fortunate enough to find a cat — its definitive host — straight away. You could say it finds a direct flight to its destination without stopping over in intermediate hosts.
Here is how it works: the cat ingests bradyzoites that are released from tissue cysts; the bradyzoites enter the intestinal cells and begin to reproduce, forming oocysts that are released into the environment. For these oocysts to become infectious, they must find a warm, humid environment — for example, a litter box that has not been cleaned for 24–36 hours. The cycle lasts between 3 and 10 days from the ingestion of tissue cysts, but only 20% of cats develop the disease following ingestion of bradyzoites.
How toxoplasmosis is contracted, symptoms and causes
The infectious period of toxoplasmosis in cats lasts approximately 20 days. Once they have had it, our cats are not lifelong carriers. A cat can contract toxoplasmosis by ingesting raw meat or soil contaminated by the faeces of another infected cat. If your cat eats wet food and dry kibble, does not eat raw meat, and lives exclusively indoors, it is very unlikely to contract toxoplasmosis.
In milder cases, the symptoms of toxoplasmosis in cats are so slight that the disease often goes unnoticed. These symptoms typically appear as diarrhoea, vomiting, weight loss, lethargy, fever, and muscle pain — very similar to a common case of flu. In more severe cases, the symptoms of toxoplasmosis in cats may include coughing, rhinitis, pneumonia, conjunctivitis, jaundice, lameness, arthritis, ascites, arrhythmia, tremors, seizures, and significant behavioural changes.
In very serious cases, severe eye conditions may also develop, such as glaucoma, uveitis, blindness, optic neuritis, retinal detachment, and lens luxation. In the most critical cases, sudden death of the cat may occur, particularly in very weakened kittens. These symptoms may appear suddenly or gradually. If toxoplasmosis in cats affects the nervous system or the respiratory tract, death can occur more rapidly.
Toxoplasmosis in cats: diagnosis and the Toxo test
The diagnosis of toxoplasmosis in cats is made through specific laboratory tests. As with humans, a serological test is required to detect antibodies — also because it is nearly impossible to identify oocysts through faecal analysis. The toxoplasmosis test in cats can yield three results, all based on IgM or IgG levels. The former indicates that the disease is active — meaning the antibodies have only just formed — while IgG indicates that the antibodies formed in the past (at least 20 days ago, or possibly longer).
The results may therefore show: the absence of both IgM and IgG, meaning the cat has never contracted the disease; the presence of IgM, meaning the cat currently has toxoplasmosis; or the presence of IgG, meaning the cat had toxoplasmosis in the past and the antibodies it developed have made it immune.
Toxoplasmosis in cats: treatment and therapy
Depending on the severity of the disease, the cat's overall health, and its age, the vet will choose the most appropriate antibiotic and dosage. Clindamycin is generally used and typically takes effect approximately 14–48 hours after administration; clinical signs improve, although the cat may take a few weeks to recover fully.
During this period it is important to monitor the cat closely to prevent any lasting effects of the disease; if the nervous system has been affected, a neurological deficit may persist even after recovery.
Toxoplasmosis in humans and risks during pregnancy
For Toxoplasma, humans are an intermediate host. The parasite's ultimate target is felines. Toxoplasmosis in humans typically produces no particular symptoms beyond those very similar to flu — a slight fever and muscle pain. Cases in which toxoplasmosis causes seizures and loss of coordination are rare, and generally only occur in people with a very weakened immune system or who are severely debilitated. Otherwise, within a few weeks — at most one month — the symptoms of toxoplasmosis in humans disappear entirely.
The situation is different for pregnant women, as it is well established that Toxoplasma can harm the foetus; in general, all gynaecologists routinely prescribe tests to check for the presence of the parasite. What is very important to remember is that the disease is not necessarily contracted from your own cat or your neighbour's. A pregnant woman can contract toxoplasmosis through the ingestion of raw or undercooked meat, cured meats, contaminated raw vegetables, unpasteurised goat's milk, or particles of infected soil or sand.
What to do if your cat has toxoplasmosis
The first thing we recommend is never leaving cat faeces in the litter box for more than 24 hours. In summer, warm humidity will help Toxoplasma become active; in winter, avoid placing the litter box near a radiator. Do not handle cat faeces with bare hands, and above all avoid touching your mouth afterwards. Stay calm and do not panic; looking into the eyes of or stroking a cat with toxoplasmosis carries no risk whatsoever. Even if oocysts end up on the cat's coat, they require the right conditions to become infectious — namely a warm, humid environment — and a cat's coat does not provide that.
If you have any doubts, speak to your trusted vet. Doctors who advise you to remove your cat from the home often do so because they are not familiar with this zoonosis and, in particular, do not have extensive experience with the routes of disease transmission between animals and humans — even though the topic is well covered in medical textbooks.
