Categories: Zoonotic Diseases

Australian professor claims that toxoplasmosis from cats causes 200 fatal car accidents annually in Australia

Professor Sarah Legge, of the Australian National University and the University of Queensland is the lead scientist of a team who carried out a study on the impact of diseases transmitted from cats to people on the Australian economy. These are zoonotic diseases.

Prof Sarah Legge. Photo: Australian National University.

I’ve not seen the actual research paper but I don’t think it’s published yet but I have seen a report on a Chinese website (good English). The report is also on the website but you have to subscribe to that to read read it. I have seen the introduction on that site.(

The economic cost of cat diseases trasmitted to Australians

Three cat diseases are referred to namely: cat scratch disease, toxoplasmosis and roundworm. Of these three the more serious in terms of economic impact is toxoplasmosis, which is caused by the transmission of toxoplasma gondii oocysts from cat faeces in cat litter or soil outside the home, thence to a person’s hands and thence finally to the mouth where they are ingested. Now, she says that that disease solely causes 200 deaths in road accidents and 6500 hospitalisations (also caused by road accidents) in Australia annually.

In all she claims that diseases transmitted from cats to people results in over 500 human deaths and 11,000 hospitalisations in Australia each year costing the Australian economy over AU$6 billion annually. This amounts to US$4.2 billion annually.

She claims that toxoplasmosis causes mental health disorders which I presume are translated into poor driving and fatal accidents. She also claims that 1 in 5 (20%) cases of schizophrenia, and 1 in 10 (10%) cases of suicide could be avoided if toxoplasma gondii infections were eliminated.


I don’t know how she and her team made the assessments with respect to the economic damage caused by cat scratch disease and roundworms. She wants all domestic cats to be kept inside at all times and for people who look after cats to wash their hands thoroughly after handling cat litter or gardening. This is to eliminate the possibility of toxoplasma gondii oocysts being transmitted via people’s hands.

Sarah Legge also states that feral cats are a disease reservoir around towns. She wants people to stop feeding them including stray cats and preventing their access to rubbish bins. As usual she supports spaying and neutering at five months of age and local government initiatives to manage stray and feral cats.


I don’t know about readers of this page but I find it very surprising that she can assess the impact of toxoplasmosis as causing 200 road deaths annually. I don’t know how she was able to extrapolate this disease to road deaths. When people have toxoplasmosis they are nearly always asymptomatic. About 30% of the world population have antibodies to toxoplasmosis and therefore they been exposed to it. Occasionally people suffer symptoms but most often they are very mild, flu-like symptoms.To the best of my knowledge there is no science which supports what Sarah Legge is stating namely that toxoplasmosis causes mental health disorders. Is there a scientific research paper on that? If so I will stand corrected.

The disease can cause blindness very rarely and it can be serious but does anybody know anybody else who’s got toxoplasmosis and how it affected them? Symptoms from the disease are very rare. Cat scratch disease is quite rare and can be dealt with effectively and the same goes for cat bites. In my estimation about 90% of cat bites and scratches are no more than irritants which can be dealt with in a commonsense way. Sometimes bites cause infections and you have to be very wary of that possibility and act quickly with antibiotic treatment.

CDC in America have a report about cat scratch disease in that country. They say the annual incidence of CSD is 4.7 per 100,000 persons under the age of 65 and a total of 12,500 patients in this group receive a cat scratched disease diagnosis annually in the US. They estimate that the total costs of treating these people to be US$2.9 million for outpatients and $6.8 million in patients. The total costs for CSD is estimated to be US$9,760,000 per year. This is obviously a tiny fraction of the $4.2 billion of economic damage stated for Australia.

Human behaviour

It is reasonable to argue that the major reason why people are bitten or scratched by cats is their behaviour? I’m not saying you can always avoid a cat scratch or bite but 90% of the time you can if you are observant enough and you know your cat well enough. And indeed if you behave in the appropriate manner towards your cat. Therefore arguably the costs of treatment and these accidents if they are true are primarily caused by the careless behaviour of people. They are the author of their own problems arguably. Therefore why punish the cat?

Also, the major cause of transmission of toxoplasmosis to people is through mishandling of raw foods. And of course the mishandling of faeces in cat litter. Once again you have to put the blame on people at least partly rather than cats. Isn’t that a fair argument?


To me, this looks like another attack on the cat by the Australian authorities. They want to eliminate the feral cat on the continent. They seek the support of scientists in achieving this goal. I strongly suspect that Professor Sarah Legge is working in conjunction with the authorities and needed to produce a paper which supports the need to clamp down on domestic cats and eliminate feral cats.

Michael Broad

Hi, I'm a 71-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I have a girlfriend, Michelle. I love nature, cats and all animals. I am concerned about their welfare.

View Comments

  • Every living creature and person is a disease reservoir, by being exposed to infection on a daily basis maintains the immune system active. She reminds me of those fools who recommend living inside an enclosed glass bottle to be safe. It looks like Australia wants to repeat the mistake of many people during the Middle Ages. Cats were thought to be agents of the devil and should be eliminated. The result was the over population of rodents and other pests which spread the black death through their fleas, and which killed millions of those cat haters. Karma is a bitch.

  • Sorry, but IMHO, she's just a whackjob. Period. People who get scratched don't know how, or can't bother to find out the proper way to interact with a cat.

    She's one of them. Not much more to say other than to watch her carefully. Methinks she's up to something no good.

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