By Fiona Macrae
Cats may be spreading brain cancer to their owners, scientists warned last night.
They have linked a parasite that breeds in cats’ stomachs with brain tumours in people.
While they can’t prove that our feline friends are to blame, they say that properly researching the link could spare some people from developing the deadly disease.
Danger to their owners? Scientists have found a link between brain tumours and a parasite that is found in both cats' stomachs and humans
Brain cancer, in its various guises, claims more than 3,500 lives a year in the UK alone, and its causes are largely unknown.
The parasite in the frame – Toxoplasma gondii – is carried by around a third of the world’s population deep inside their brains and has been linked to personality changes, in people as well as animals.
The parasite, which infects up to 34 per cent of Britons, has a complicated lifecycle but can only breed inside cats, which then pass their microscopic eggs, spreading the infection.
Pregnant women are already advised not to empty cat litter trays, as the parasite can be fatal to unborn babies, and now it seems the health risks may extend to other people.
French scientists collected global data on brain cancers in men and women and compared it with figures on T. gondii infection rates.
This showed brain cancer rates to be highest in countries where the parasite was most prevalent – even when other factors such as income were taken into account.
The scientists, led by Frederic Thomas, from the CNRS research institute in Montpellier, said: ‘We feel our results are sufficiently strong to propose that T. gondii potentially increases the risk of brain cancer in humans.’
The parasite has already been linked to brain tumours in animals.
There is also other evidence that T. gondii has effects on the brain leading to changes in behaviour.
Infected rats are known to lose their fear of cats, making it more likely that they will be killed and eaten.
This is good from the parasite’s point of view, as it speeds its passage into the cat gut, allowing it to breed and eventually spread.
The parasite may also sway human behaviour, with research suggesting it turns men into aggressive, jealous ‘alley cats’, while transforming women into ‘sex kittens’.
Other research has pointed to a strong link between T. gondii and schizophrenia.
Chief causes of infection in humans are consuming undercooked meat, especially lamb, pork and venison, and ingesting water, soil or anything else contaminated by cat faeces.
The scientists behind the latest study acknowledged that they hadn’t proved that cats are spreading brain cancer but added: ‘Clearly, further research is necessary to determine the proximate links between T. gondii and different types of brain tumours and to investigate a mechanism of action.
‘Establishing a link between T. gondii and brain cancers could open the door to potential means to reduce cancer risk.’