Toxoplasma gondii: The Parasite Which Causes Road Accidents?

A car crash becomes more likely after infection. Source: Pixabay.

It turns out that our sci-fi movies could have inadvertently taken inspiration from real life, as the evidence suggests a parasite could be messing with our nervous systems.

We’ve all seen the movies. Invasion of the Bodysnatchers. The Thing. The alien life form, parasite or whatever sci-fi twist is added takes over the human host and influences their behaviour. While the quality of the movies is a matter of taste, there was always one comfort: they were all fiction. However, as it turns out, this might not be as true as I once thought.

Toxoplasma gondii

In the real world, there are several commonly known parasites: tapeworms, scabies mites and the royal family being some examples. However, toxoplasma gondii – despite 30-50% of the worldwide population being infected – remains relatively unknown in wider society. One of the reasons for this is that infection is considered largely asymptomatic.

A commonly known parasite native to the UK. Source: Wikimedia Commons.

Professor Jaroslav Felgr – a Czech parasitologist and evolutionary biologist – has spent a large chunk of his career studying the parasite. He found that humans with latent toxoplasmosis – those who are infected but don’t show symptoms – have a significantly higher risk of road traffic accidents than noninfected subjects. The supposed reason for this is that infection lengthens reaction times. In the paper he goes on to say that the parasite may in fact be a highly underestimated public health crisis. 

Further evidence suggests that toxoplasma gondii could have a role in the development of mental illnesses. One study discusses a link with schizophrenia, and while they admit it is plausible, they conclude that more direct evidence is necessary. A similar study discusses a link with bipolar disorder and while they do reach the same conclusion, they add that every attempt to prevent toxoplasmosis should be encouraged” in waiting for a vaccine. 

Feline discouraged 

Given that cats are the primary hosts of the parasite, those who live with one are higher on the at-risk-list. This is because the parasite can be passed on via their faeces; though don’t worry, looking at cats on the internet doesn’t hold quite the same risk.

Better to appreciate cats in this way if the parasite worries you. Source: Raita Futo.

In addition the parasite is transferred via food. Typically this is from the consumption of undercooked infected meat, or from contaminated fruit or vegetables.

The changing climate

On top of all of this I found out that as a result of climate change, the parasite could become more prevalent. Right now it is quite widely spread in humid, tropical areas. In drier or colder areas it is rarer. However, with our changing climate, both temperature and humidity increases in the winter could lead to the parasite surviving and spreading further through Europe.

An image of Toxoplasma gondii in mouse ascitic fluid.

In addition, human behaviour has an influence. For example, rates of infection in humans dropped when farm animals began to be kept indoors due to the scale of industrial farming. Nowadays the increased calls for animal welfare – and therefore allowing them outside – could lead to higher rates of infected meat, as the farm animals come into contact with nature. 

The master plan

So we have this parasite which is known to influence human behaviour. In addition, our changing climate favours its survival. Not to mention our own behaviour could be leading to the spread of said parasite. Could we really be living in our very own sci-fi movie? With recent world events like a reality TV star becoming the leader of a world power, or episodes of Black Mirror coming to life (David Cameron and the pig for example) it’s hardly difficult to believe. 

Maybe that’s it. Perhaps we’re all slowly succumbing to the whim of a parasite. The downfall of humanity and our civilisation due to one parasite’s unrelenting desire to spread. In 50 years as we’re zooming around in our electric cars there will be crash after crash until only cats remain, the real target host. Or the more likely option: I’m exaggerating for dramatic effect. 

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Jack McGovan is a recent graduate in chemistry with a specialisation in ‘Energy and Sustainable Chemistry’ from the University of Groningen, the Netherlands. Following a job as a student journalist covering the energy transition, he has moved to Berlin where he is following his passion for working towards creating a fairer and more sustainable world. Seeing a gap in the way in which the world of science was communicated, he founded Delta-S. By writing source based content, he hopes to communicate his findings to a wider audience.