What is Toxoplasmosis?

Toxoplasmosis is a disease that affects both animals and humans. It is caused by the protozoan parasite Toxoplasma gondii. Infection is quite common, whereas the disease is relatively rare.

Cats (felines) are the definitive hosts of the parasite, meaning that the adult forms of the parasite develop in them, while other animals and humans are the intermediate hosts (the larval or immature forms of the parasite develop in these hosts).

Transmission to Humans

Humans can become infected in several ways, including gardening with bare hands, cleaning the litter box of an infected cat without gloves, contact with objects contaminated with infected cat feces, consumption of contaminated water, eating contaminated raw or undercooked meat (mainly pork, lamb, beef), consumption of inadequately washed fruits & vegetables, handling raw meat, or contamination of utensils from objects used on infected meat, and finally through intrauterine infection.

Human infection through direct contact with an infected cat is extremely rare, as the parasite requires 1–5 days to become infectious and infected cats also rarely have diarrhea, while grooming themselves regularly, thus limiting the possibility of contamination of the fur or the presence of infected feces in their fur.

Transmission to Cats

Stray cats are most commonly infected due to their lifestyle. Direct contact with feces from infected cats, hunting (eating rodents & birds), as well as due to easy access to garbage, where raw meat may be present.

After becoming infected, the cat sheds immature oocysts for a period of 1–2 weeks. Shedding then stops due to the immunity the cat develops.

In the environment, oocysts mature within 1–5 days and can survive for up to 18 months, even under adverse conditions.

Clinical Signs in Infected Cats

Cats that become infected during their lifetime remain, for the most part, asymptomatic. However, a small percentage of young or immunocompromised cats may exhibit neuromuscular symptoms (seizures, ataxia, muscle tremors), respiratory and gastrointestinal symptoms.

Symptoms in Humans

Infection in humans usually does not cause symptoms. In some cases, people may experience fever, muscle pain, vision problems, and swollen lymph nodes.

Of particular importance is the infection of pregnant women, as the infection affects the fetus (congenital toxoplasmosis). Congenital toxoplasmosis can cause damage to the fetus’s brain and eyes (hydrocephalus, nystagmus, strabismus, microphthalmia) and even fetal death.

Diagnosis

A definitive diagnosis is made through a serological blood test. Specifically, detection of IgM immunoglobulins in the cat’s blood serum in the first weeks after the initial infection, or IgG during the period of clinical onset of the disease, as well as the chronic phase.

Treatment

Treatment for toxoplasmosis includes the administration of antiprotozoal medications for approximately 30 days. Antitoxoplasmosis treatment is administered to animals showing clinical symptoms of the disease.

Toxoplasmosis Prevention and Pregnancy

Prevention for pregnant women should include strict hygiene measures. Specifically, pregnant women are recommended to:

1. Eat well-cooked meat (above 65 °C), or meat that has been previously frozen at -20 °C for 3 days.
2. Avoid pre-packaged salads.
3. When preparing meals, do not use the same knives used for raw meat to cut vegetables or fruit, or vice versa.
4. Thoroughly wash the fruits and vegetables they are going to consume.
5. Use gloves when gardening and wash their hands thoroughly after gardening.
6. If they have pet cats that go outdoors, cleaning the litter box should be done using gloves daily. Ideally, for the duration of the pregnancy, the cat should be confined to the house, and if this is not possible, the litter box should be cleaned by another person in the house.
7. Their pet cats should be fed only dry or canned commercial food, or meat that has been thoroughly cooked, or frozen at -20°C for 3 days.
8. Avoid contact with stray cats.

In conclusion, cats should NOT be removed from the house, as mentioned above, they only shed the protozoan in their feces for the first 3-10 days after infection. A cat that has been infected in the past, in a new infection will not shed the protozoan during a new infection, due to the existing immunity it has developed from the initial infection. This immunity lasts at least 6 years. To protect the fetus, in any case, pregnant women must meticulously follow the preventive measures mentioned above.