A cat can be comforting to own, but the purring pet could also be harming your health.
A study published last week has found that women are at increased risk of attempting suicide if they're infected with a particular parasite spread through contact with cat faeces or from eating undercooked meat or unwashed vegetables.
Toxoplasma gondii (T. gondii) hides in cells in the brain and muscles, often without producing symptoms. The infection, which goes by the name of toxoplasmosis, has been linked to mental illness, such as schizophrenia, and also to changes in behaviour.
Researchers from the University of Maryland in the US and the University of Aarhus in Denmark analysed data from more than 45,000 Danish women and their babies. The study's findings were published last week in the Archives of General Psychiatry.
'We can't say with certainty that T. gondii caused the women to try to kill themselves, but we did find a predictive association between the infection and suicide attempts later in life that warrants additional studies,' says Teodor Postolache, the senior author and an associate professor of psychiatry who's director of Maryland's mood and anxiety programme. 'We plan to continue our research into this possible connection.'
The study found that women infected with the parasite were 50 per cent likelier to attempt suicide compared with those who were not infected, and the risk seemed to rise with increasing levels of the T. gondii antibodies. Previous mental illness did not appear to significantly alter these findings.
Postolache's research team in Maryland was the first to report a connection between the parasite and suicidal behaviour in 2009.
T. gondii thrives in the intestines of cats, and it is spread through oocysts passed in their faeces. All warm-blooded animals can become infected through ingestion of these oocysts. The organism spreads to their brain and muscles, hiding from the immune system within 'cysts' inside cells.
Postolache stresses that further research is needed to learn more about the connection between T. gondii and suicide. Test your knowledge of the parasite below.
1. How can humans become infected by T. gondii?
a. Changing infected cats' litter trays
b. Drinking water from a contaminated source
c. Not washing kitchen knives after preparing raw meat before handling another food item
2. What in the estimated rate of T. gondii infection among the world's population?
a. One in three
b. One in 10
c. One in 20
3. True or false: a pregnant woman can pass the parasite on to the foetus.
4. True or false: there is a vaccine to prevent toxoplasmosis in humans.
Answers: 1. all are correct; 2. a; 3. a (infected pregnant women may miscarry, give birth prematurely, or have babies with eye or brain damage); 4. b (hygiene is the best prevention)