Sir Richard Branson tells entrepreneurs to think big, while Sir Alan Sugar says they should hide their fear.

No business manual has yet advised people to get a cat – but maybe they should.

A study has found people infected with a parasite spread by pet cats are far more likely to start their own business or aspire to be entrepreneurs.

The parasite in question is Toxoplasma gondii, which affects a third of people in Britain at some point in their lives, normally causing mild flu-like symptoms.

But it can also change people's behaviour because it infects cats' prey and affects their brains in a way that makes them easier for the cat to catch.

Researchers led by the University of Colorado tested 1,495 students for T. gondii, finding those positive for the parasite were 1.4 times more likely to study business as their main subject.

A parasite commonly transmitted by domestic cats could make people more likely to take risks and to prioritise ambition and success, which makes them more likely to be entrepreneurs

People infected with the bug are 1.7 times more likely to specialise in ‘management and entrepreneurship’.

And infected people at entrepreneurial events are 1.8 times more likely to have started their own business.

Once passed on to a human by a cat, the parasite is believed to make people more entrepreneurial by encouraging risk-taking and ambition.

The effect is most likely a bizarre consequence of its need to affect rats’ brains and make them more risk-taking, so they are more likely to be eaten by cats.

A cat’s stomach is the only place the bug can reproduce.

Even in countries with high rates of T. gondii, the researchers found similarly high rates of people running their own businesses.

The parasite is 'incredibly widespread' around the world

WHAT IS TOXOPLASMA GONDII? Toxoplasma gondii is a parasite which causes an infection called toxoplasmosis. The parasite is common worldwide and 60 million people in the US are thought to be infected by it. Few people who are infected show any symptoms because a healthy immune system can fight it off, but it can cause flu-like effects. However, it can cause more serious complications in pregnant women and people with weak immune systems. Toxoplasmosis can be caught from pet cats or their litter trays, eating undercooked contaminated meat, or drinking water contaminated by the parasite. Most people's infections go away without treatment but medication is available for those who are more at risk of serious complications. Source: Centers for Disease Control and Prevention Advertisement

Dr Pieter Johnson, who led the study from the University of Colorado, said: ‘Toxoplasma gondii is an incredibly widespread and successful parasite, occurring in many parts of the world and in over a hundred different host species, including humans.

‘We found that infected individuals and countries with a higher infection prevalence both exhibited greater tendencies of entrepreneurship.

‘If this relationship is causal, it could be that T. gondii infection lowers people’s “fear of failure” and enhances risk-taking within the business world.’

Some 350,000 people a year infected in the UK

An estimated 350,000 people a year are infected with T. gondii in the UK, which is spread through uncooked meat as well as cat litter trays.

It has been linked with drug and alcohol abuse, as well as a greater risk of car crashes, while women who ingest the parasite in early pregnancy can suffer a miscarriage or stillbirth.

It can be treated using antimalarial medicines and antibiotics.

The US researchers gave 1,495 students a saliva test for T. gondii, finding 31 per cent of those who studied business as their main subject tested positive for the parasite, compared to just 22 per cent of those who did not.

People infected with the Toxoplasma gondii parasite are 1.4 times more likely to study business at university than those without the parasite, according to University of Colorado scientists

Behaviour changes could be caused by testosterone boost

Among those who specialised in management and entrepreneurship, 41 per cent were positive, compared to 29 per cent who chose subjects like accounting and finance.

The link with risk-taking behaviour is believed by some experts to be driven by a surge of testosterone caused by the parasite.

This, according to the US study published in the journal Proceedings of the Royal Society B, may push someone to focus on ego, ambition, achievement and material possessions. These tend to be important to entrepreneurs.