Toxoplasmosis is one of the most well-known zoonotic diseases, meaning it can be transmitted from animals to humans. The problem is, there is plenty of misinformation out there and some of it leads to unnecessary concern and anxiety for cat owners.
What is toxoplasmosis?
Toxoplasmosis is caused by infection with Toxoplasma gondii (T gondii), a coccidian parasite that is present around the world. Kittens and adult cats can be infected with the parasite, but research shows that owning a cat does not increase your risk of being infected by this parasite.
T gondii is a very well adapted parasite and this means that it rarely causes significant disease in an infected host. It can infect almost any warm-blooded animal, but the cat is required to complete the lifecycle.
The only time a cat, human or other animal develops clinical disease associated with toxoplasmosis is if their immune system does not prevent widespread replication of the organism.
How do cats get toxoplasmosis?
Cats generally become infected after eating raw or undercooked meat, or prey species such as rats and mice that contain the T gondii cysts. Cats are definitive hosts and this means they are the only animal in which replication of T gondii results in the shedding of oocysts (eggs) in the faeces (a source of infection.)
Toxoplasmosis in humans
The majority of human infections are thought to occur through the ingestion of undercooked meat (containing tissue cysts) or fruit or vegetables that have come in contact with soil that has been contaminated with faeces containing T gondii eggs.
Most healthy people with a normally functioning immune system will not have any serious clinical signs of toxoplasmosis apart from those who have impaired immunity including:
- Pregnant women because of the risk to their developing baby (the foetus)
- Babies and young children
- Very elderly people
- Immunosuppressed people e.g. those receiving anticancer therapy
Toxoplasmosis and pregnancy
For women infected with toxoplasmosis during their pregnancy, there is a risk that the infection can lead to problems with the unborn foetus. In a minority of cases, the infection can result in abortion, birth defects or neurological problems.
How to reduce the transmission of toxoplasmosis
Although the risk of transmission of toxoplasmosis from a cat to its owner is very low, it can be reduced further by following these recommendations:
- Fruit and vegetables should be thoroughly washed before eating
- Meat should be cooked to a minimum of 58°C for 10 minutes or 61°C. Microwaving is not safe as the heating is uneven
- Freeze meat at -12°C to -20°C for three days before consumption as this can kill the tissue cysts
- Feed only properly cooked food or commercial cat food to your cat to avoid infection
- People in ‘high risk’ groups (e.g. pregnant women, immunosuppressed individuals, young children) should not have contact with or handle the cat’s litter tray
- Wear gloves when handling cat litter and wash hands thoroughly after cleaning a litter tray
- Empty litter trays daily and dispose of litter safely
- Cover children’s sandpits when not in use to prevent cats from using them as litter trays
If you have any questions or need more information about toxoplasmosis you should always ask your veterinarian.