Is 'crazy cat lady' a realistic fear?

Cat Collins ponders how suicidal attraction theory in rats and cats may lead to schizophrenia, personality changes and car accidents

Nobody likes to feel like a puppet. The idea of freewill is something that is inherently connected to human nature, so the conflicting suggestion that human behaviour may be due to a number of parasites controlling your brains may be disturbing to some. A rather extreme example of this in the animal world exists through the Lancet liver fluke, a parasite so desperate to access cattle liver in enslaves an ant, forcing it to climb blades of grass and be eaten. Many would like to believe that this is different for humans – human brains are incredibly complicated and could resist the mechanisms of a lowly parasite. Or can they?

Domestic cats are widespread across the UK, residing in 18% of our households. It is difficult to escape them, even if you yourself are not partial to these furry felines. These cats can commonly carry Toxoplasma gondii, a parasite that functions best in the cat’s’ intestine. However, if T. gondii wants to spread and infect as many cats as possible, it must leave its comfy home in the cat and exit via. the faeces to the outside world. It is exposed; it cannot reproduce; it is desperate. Fortunately for the parasite, it can infect almost any warm-blooded animal that happens to encounter it – take, for example, a rat. Okay, so it’s not perfect – it cannot complete its sexual life cycle – but it can take a spot in the driver’s seat at the rat’s brain.

At this point, the parasite may be defeated, although cat predate rats, their odour acts as a natural deterrent. Yet T. gondii overcomes this, changing this innate aversion and manipulating the rat to actually become attracted to cat odour. In fact, some studies suggest that T. Gondii can cause the rat to become sexually attracted to cat urine; innate feat replaces with the innate urge to mate. However, instead of the rat finding a new mate, the cat spots it… game over. Just like that, T. gongii is back in its comfortable cat home.

But what if T. gondii does not infect a rat and infects an animal not likely to be eaten by a cat – say, a human? There is no evidence suggesting that T. gondii knows it’s not in the right host and so it adopts the same mechanisms – but the human brain, complicated as it is, behaves differently. Toxoplasmosis is a buzzword for pregnant women as infection could cause serious complications to the baby. It also can be prominent in immunocompromised individuals. However, in a regular person the infection means nothing – it seems relatively asymptomatic.

Czech scientist Jaroslav Flegr first investigated T. gondii human manipulation after becoming convinced his personality was affected by the two cars living with his family. Eccentric as this may seem, he produced studies that showed infected men to be more reckless and rule-breaking. He even suggested that this parasite may be leading to an increase in car accents. Perhaps more believable, infections with Toxoplasma gondii has found a striking relationship with schizophrenia, depression, and a multitude of other neurological disorders.

In light of this, is it time to re-evaluate the place of Mittens and Tom in our modern homes? Most cannot resist these furry felines – Flegr himself has two cats despite investigating their puppeteer-like friends. I myself have a cat called Pip and there’re no way we’re getting rid of him, whether we go crazy or not.

From Issue 12