The risk of toxoplasmosis is real
Toxoplasmosis is a disease that results from infection with toxoplasma gondii, a parasitic organism.
While people can become infected if they come into contact with cat faeces that contain the parasite, the parasite’s lifecycle actually begins with the cat’s typical prey: a mouse.
According to a National Geographic article, a mouse infected with T gondii catches the whiff of cat urine and runs towards the source – right into the jaws of a cat. This suicide mission is the work of the single-celled parasite, which has commandeered the mouse’s brain and altered it as a vehicle for sneaking the parasite into a cat. T gondii infects a wide variety of mammals, but it only completes its lifecycle in the guts of a cat. It can only produce eggs when infecting a cat.
When a cat ingests an infected prey or other infected raw meat, the parasite is released into the cat’s digestive tract. The organisms then multiply and produce eggs, excreted in large numbers in the cat’s faeces.
Cats only shed the organism for a few days in their entire life, so the chance of human exposure is relatively small.
Humans may accidentally ingest the parasites through cats. This happens by touching your mouth after gardening or cleaning a litter box or touching anything that has come in contact with infected cat faeces.
Other ways people can get toxoplasmosis is through eating undercooked meat, accidentally ingesting contaminated soil (by not washing your hands after gardening or eating unwashed fruit and vegetables from the garden), or drinking water contaminated with T gondii. The organism can sometimes be present in unpasteurised dairy products, such as goat’s milk.
The National Geographic article said one in three people around the world carry T gondii – although the proportion varies a lot between countries – and some scientists have suggested it can affect human personality and behaviour.
This field is rife with tenuous evidence, but the most compelling set of data concerns schizophrenia.
There are many studies showing that people with schizophrenia are more likely to be infected by T gondii and a couple which show that infection precedes the onset of symptoms. But even this connection is controversial. After all, T gondii is common and schizophrenia is rare.
Most healthy people infected with toxoplasmosis will show no signs or symptoms, and could possibly not be aware that they are infected.
However, some develop signs and symptoms similar to those of the flu, such as body aches, swollen lymph nodes, headache, fever and fatigue.
Most cats that have toxoplasmosis can recover with treatment. Treatment usually involves a course of an antibiotic called Clindamycin. Other drugs can be used and combined to act together to inhibit the reproduction of Toxoplasma gondii. Treatment must be started as soon as possible after diagnosis and continued for several days after signs have disappeared. No vaccine is as yet available to prevent either Toxoplasma gondii infection or toxoplasmosis in cats, humans, or other species.