Parasite responsible for Australians losing job, road accidents; here’s why toxoplasmosis is creating havoc

A parasite carried in cat faeces and raw meat is silently affecting millions of Australians, with new research linking it to slower reaction times, higher risk-taking, and even job losses. The parasite Toxoplasma gondii causes toxoplasmosis, one of the most widespread infections in the world.

A study published in April 2025 in Science Direct, ‘An inexpensive method to measure latent toxoplasmosis and its behavioral consequences,’ estimates that more than two billion people globally carry it.

According to a news.com.au article, around 20 per cent of Australians are affected by it, that are causing mental health issues and reaction times.


It is often contracted by handling cat litter after cats eat infected mice or by consuming contaminated raw meat. Most people never realise they are infected, as symptoms are rare in healthy individuals.

How does it change behaviour

Research from the University of Melbourne, Lancaster University, and Zeppelin University found that toxoplasmosis can subtly alter human behaviour and decision-making.

Dr Michele Garagnani, senior lecturer at the University of Melbourne, told news.com.au that infected people are about two per cent more likely to be involved in a car crash.

Studies have also linked the parasite to reduced self-control, increased impatience, and greater appetite for risky behaviour such as drinking, drug use, and impulsive business ventures.

A larger survey of 1,010 people found that those with the infection were more likely to smoke, drink alcohol, have mental health problems, and experience unemployment. On average, infected individuals earned less than those who were not infected.

The science behind it

Previous studies have shown that the parasite can affect dopamine levels in the brain, influencing mood, risk-taking, and reaction time. In one trial, people with toxoplasmosis had slightly slower responses to visual cues, which could explain the increased crash risk.

The economic and social effects are significant. Research published in Acta Psychologica found infected individuals in the UK earned about £2,500 less per year and had an 11 per cent lower employment rate.

A new way to detect it

Until now, toxoplasmosis has been diagnosed through blood or saliva tests. But Dr Garagnani’s team has developed an online reaction-time tool that can identify likely infection with 97 per cent accuracy, as per the news.com.au report.

The test involves a two-minute task where participants respond to colour changes on a screen. Researchers measure both speed and ability to maintain focus, then compare results to known infection patterns.

Who is most at risk?

While healthy people usually show no apparent symptoms, toxoplasmosis can be dangerous for those with weakened immune systems and pregnant women, as it may cause serious health problems for unborn babies.

The World Health Organisation still lists it as a “neglected parasitic infection,” but has recently shifted focus to other global health threats like tuberculosis.

How to protect yourself

Experts recommend wearing gloves or a mask when handling cat litter, washing hands thoroughly, and avoiding undercooked or raw meat.

Although the infection’s effects are small on an individual level, researchers warn that its widespread presence means it could have a large-scale impact on society, from road safety to workplace productivity.