And in more ways than you might suspect. Having the Fluffy Vermin about makes you nearly three times more likely to be involved in a car crash. This is no false correlation fallacy; a number of studies have confirmed this. But why?
We all know the Fluffy Vermin carry a host of pathogens: Bartonella, Yersinia, Salmonella, Campylobacter, Capnocytophaga, C. diff, UTI-related and ESBL producing E. coli to name a few, and you might have thought the only risk from the Fluffy Vermin was them licking their arse then licking you. Ick. Or Pasteurella meningitis in children – including the girl who allowed her cat to lick tuna from her nose. Ick. But what about Toxoplasma gondii?Toxo is a really interesting parasite and cats are its ‘definitive host’ – that is, toxo can only complete its lifecycle within the intestine of the Fluffy Vermin. When mice are infected with toxo they permanently lose their innate fear of cats – mice have evolved to flee the odour of cat urine, but toxo affects mouse brain chemistry to make the smell attractive. In this marvellous bit of co-evolution mouse gets infected with Toxoplasma, loses fear of Fluffy Vermin, is attracted to smell of pussy (c’mon, you just soooo knew that was coming), wanders up to Fluffy Vermin to say ‘will you be my friend’ and is promptly eaten, thus allowing toxo to complete its life cycle.
I’ve long argued that we are but a social care provider for our Microbial Overlords and it transpires that toxo’s impact on risk aversion isn’t limited to mice. Within the past decade many independent studies have shown that toxo is implicated in higher rates of workplace accidents and suicides as well as car crashes. It is also an important risk factor for schizophrenia probably because toxo has two genes for making l-DOPA, the precursor molecule to dopamine. Dopamine system dysfunctions are associated with schizophrenia and ADHD.
Some of toxo’s effects are likely to be due to the same dopamine / tryptophan manipulation which aids transmission from intermediate to definitive host through predation but there is also evidence toxo hitches a lift in white blood cells where it stimulates production of another neurotransmitter called GABA (γ-amino butyric acid).
So, Crazy Cat Lady Syndrome really does exist. And 30% of the world’s population is seropositive for toxo.
There is a great review article here.