Review study by Australians is intended to denigrate the domestic cat

This is my opinion. I form my opinion from many years of reading these reports. I have noticed a trend: Australian scientists looking for ways to criticise the domestic cat for carrying the zoonotic disease toxoplasmosis.

Toxoplasma gondii cyst in mouse brain.
Toxoplasma gondii cyst in mouse brain. Image in public domain.

From time to time, Australian scientists like to get together to hatch a plan to denigrate the domestic cat with the long-term intention of reducing cat ownership in Australia in order to protect native wildlife from predation by cats allowed outdoors unsupervised.

And I’m going to report on an instance of this which has currently hit the news media headlines. It concerns a review report which means that Australian scientists have reviewed previous reports of published studies on scientific journal websites.

And in this instance, they reviewed studies concerning the Toxoplasma gondii parasite which is carried by the domestic cat for a short time in their lives and which is passed in a cat’s faeces as oocyts (eggs) which in turn can be ingested by people thereby transferring toxoplasmosis from the cat to people (zoonosis).

It has been proposed by some scientists in these previous studies that toxoplasmosis can cause schizophrenia in people. And this is where the scientists denigrate the domestic cat. If they can “prove” that cats give people schizophrenia it’s going to result in at least some cats being relinquished to shelters or simply abandoned on the street somewhere.

RELATED: Cat scratch fever misdiagnosed as schizophrenia

But the issue here is that these early research papers are very dubious. It seems to me that in many instances the researchers have an ulterior motive or a hidden agenda which is to criticise a domestic cat to reduce cat ownership.

And it’s reported that Australian researchers analysed 17 previous studies (from an initial selection of 1915!) published over the past 44 years in 11 countries. And the lead researcher, John McGrath, a psychiatrist, from the Queensland Centre for Mental Health Research, concludes, “We found an association between broadly defined cat ownership and increased odds of developing schizophrenia-related disorders”.

RELATED: Is toxoplasmosis a serious problem for humans?

The theory that schizophrenia in people can be caused by cat faeces come from a 1995 study. But it should be stressed that these previous studies are not particularly solid in their conclusions. Not all studies have found this association.

It is said that the new analysis of 17 studies found “a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders”.

An important point is that of the 17 studies, 15 were “case-controlled studies”. The studies do not prove cause and effect. They just look at things and it is possible to come to the wrong conclusions.

And it is admitted that a number of the studies were of low quality. However, despite this admission, the researchers concluded that their report supports an association between cat ownership and schizophrenia-related disorders.

“Our findings support an association between cat exposure and an increased risk of broadly defined schizophrenia-related disorders; however, the findings related to PLE as an outcome are mixed. There is a need for more high-quality studies in this field.”

Study conclusion

Uncooked foods

What I have not seen is a reference to the much more common cause of toxoplasmosis in people namely the eating of unpasteurised milk, poorly prepared raw foods containing oocysts. It’s far more common to get the disease from that source than from cats.

My conclusion is that people should not take this report with any seriousness. I don’t want to be biased or criticise the findings of this research but it seems to me to be scaremongering and very dubious science. I’m yet to see some solid science on the domestic cat being a danger to people because it can transfer toxoplasmosis to them and thereby cause schizophrenia-related diseases in these people.


John J McGrath, Carmen C W Lim, Sukanta Saha, Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis, Schizophrenia Bulletin, 2023;, sbad168,

Infographic on toxoplasmosis

Toxoplasmosis in cats and people
Toxoplasmosis in cats and people. The infographic is by MikeB and it is free to use under a Creative Commons: ATTRIBUTION-NODERIVS CC BY-ND license. Click on the infographic. Click on the present image to enlarge it. Right click it and select ‘save as’.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Toxoplasmosis is a risk management exercise for the pregnant mum

Risk management of toxoplasmosis for the pregnant mother.

I’ve decided that the zoonotic disease, toxoplasmosis, which often is discussed on the Internet negatively, is a risk management exercise for the pregnant mum. For me, the phrase “risk management” is appropriate in this instance. It’s about identifying and understanding the risk and mitigating the possibilities of infection. There is still some misunderstandings surrounding this disease.

Potential severe consequences demand risk management

The risk needs to be assessed in terms of its likelihood of occurrence and potential impact. Okay, we know that a Toxoplasma gondii infection of a pregnant mum can harm their unborn baby. Or the baby can be born normally but develop problems in the future. These problems can be severe such as cognitive impairment, eye and ear problems. It can result in the loss of the unborn child.

Occurrence can be eliminated

They are severe enough to assess the risk as potentially high in terms of its impact. That point I think needs to be made. But what about the likelihood of occurrence? This is an area I think which is misunderstood.

It is an area which significantly reduces the level of risk. Also, this level of risk can be mitigated. But it must be said that the mitigation must be total. I can understand fully why pregnant mums might be fearful of having a cat in the family when they are pregnant.

Getting rid of cats is an extreme mitigation exercise

There are some women who think that pregnant mums who keep their cats are bad mothers. I’ve recently written about a couple of workplace women, one of them was pregnant and her friend said that she was a bad mother for not getting rid of her four cats. The pregnant mum was baffled at the severity of the suggestion.

But the critical woman was supported by her female friends at the workplace, which must have been difficult for the pregnant mum but she held her ground and had assessed the risk I think sensibly.

Usual mode of transmission does not concern cats

Risk assessment can involve what is called qualitative and quantitative analysis to determine the severity of risks and their potential consequences. As mentioned, the potential consequences are high but let’s look at the chances getting an infection of Toxoplasma gondii from a cat or getting it from another source.

The point to be made here is that toxoplasmosis is normally transmitted to people through the ingestion of the parasite by eating undercooked or raw meat, by handling contaminated soil and through contact with cat faeces containing the parasite in the form of Toxoplasma gondii oocysts (small eggs in a shell).

Most human infections of toxoplasmosis come from eating undercooked or raw meat. In my assessment, the next in line possibility would come from contaminated soil. This means gardening and turning over soil where the family cat has defecated. Third in line in terms of risk would be an infection from handling cat litter while cleaning out the cat litter tray because of what I say next.

Eliminating the risk with cat litter tray

It is entirely possible to completely eliminate this risk by letting someone else other than the pregnant mum do the litter box cleaning. The same would largely apply to gardening.

Very limited time when cat sheds oocysts

And in assessing the risk, people need to realise that although cats can shed the toxoplasma gondii parasite in their faeces the period of shedding can last for about 1-2 weeks after the initial infection of the cat. This happens once in a cat’s life. Cats become infected by ingesting infected prey such as birds or rodents.

Hunting and indoor cats

So, let’s look at that risk. You live with a full-time indoor cat with little or zero chance of eating a mouse or a bird. Therefore, keeping a domestic cat indoors full-time would be a very effective way of mitigating the possibility of the risk becoming a reality. Note: I realise it would be hard to keep an indoor/outdoor cat inside but if you have a full-time indoor cat already you can see how the risk is mitigated.

And knowing that a domestic cat can only shed the toxoplasma gondii oocysts for a very short period of time in their life must help calm the nerves and reduce the risk.

Risk management vis-a-vis handling foods

Returning to undercooked meat and handling vegetables, this is where risk management can really take place for the pregnant mum. She can allow her husband or partner to handle these foods during pregnancy. That would be one method of risk management.

Or she might where gloves when gardening. She should wash vegetables thoroughly. As part of the risk assessment, it’s worth noting that the pregnant mum would get the disease by handling vegetables which contain the oocysts and then putting their hands into their mouth. That’s how the transmission takes place. This would be unusual anyway, once again reducing the risk.

Knowledge and hygiene

The woman armed with this knowledge can take steps to mitigate the risk further. It’s about knowledge and acting upon that knowledge to eliminate risk. Proper hygiene is the answer including washing hands and thoroughly cooking meat.

Extreme mitigations not needed

The point here is that the cat should not be automatically vilified. Although the women who criticised the pregnant mum that I mention above had good intentions, their response to the fact that the pregnant mum was going to keep cats was extreme and to be honest misinformed.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Is cat poop good for plants?

The question is: can cat faeces go into compost? I did some research on the internet some time ago and concluded that it is unwise to use cat faeces in compost. The general consensus is that it shouldn’t be done (click this link for another article on the topic). Although, a strict answer to the question in the title will probably be, yes, it’s good, because when animal faeces are added to dirt it is called manure and manure has all the sorts of things plants need to grow like nitrogen.

Can cat poop be used in compost?
Can cat poop be used in compost? Well, yes and no! Probably unwise to for peace of mind. Picture of compost: Pixabay. Image: MikeB.

The problem which always comes in a discussion about cat faeces is toxoplasmosis. People cite this parasitic disease as a barrier to using cat poop as a manure. For example, a gardening website starts straight off by stating that cats “are the only animal known to excrete toxoplasmosis eggs in their faeces”. These are oocysts which are a source of infection. And toxoplasmosis can be a problematic disease in people although it is said that many more people are already infected than people imagine.

The point that is frequently overlooked is that these infective oocysts are only passed for a very short time after initial exposure. Also, if your cat is a full-time indoor cat who only eats cat food, she is not likely to be infected. A cat becomes infected with toxoplasmosis from eating raw or undercooked pork, beef, mutton or veal or unpasteurised dairy products that contains toxoplasma organisms.

So, when the experts pooh-pooh (excuse the pun) the idea of cat poop making manure they’re overlooking this important aspect of the life cycle of this protozoan. In contrast, the use of unprocessed human faeces as fertiliser is not criticised so much but it does contain pathogens and therefore it’s a risky practice.

From my perspective, I wouldn’t use any poop, either human or cat, for manure. It’s too problematic and too unpleasant to be honest! Although it does seem a good idea in terms of the environment and creating this natural loop between ingesting food and using the waste to create more food. It sounds like a perfect example of sustainability.

Toxoplasmosis has always been used to criticise the domestic or feral cat. It is overdone for the reasons stated in the third paragraph above. Serologic tests show whether a cat has ever been exposed to the disease. A positive test in a healthy cat indicates that the cat has acquired active immunity and is not a source of infection to humans. FYI – toxoplasmosis is a zoonotic disease.

I have some more articles (in fact, I have a lot more articles!) on toxoplasmosis so if this topic interests you then please click on one of the links below.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Premenstrual syndrome and toxoplasmosis

I would like to quickly put the record straight, as I see it, about the news media’s reporting of a link between premenstrual syndrome and toxoplasmosis. The Irish News are reporting on this today although the Mexican University study to which they refer, on this topic, was published online in December 2016. The Irish Times reporter has acted irresponsibly in writing: “A STUDY involving 151 women linked toxoplasma gondii – a parasite carried by cats – to severe pre-menstrual syndrome (PMS) symptoms”. This distorts the findings of the study. I explain why below.

Toxoplasma gondii
Toxoplasma gondii. My thanks to Wikipedia for the image.

The way the news was reported may make some women anxious because it builds on an already, I would argue, distorted story that pregnant women should get rid of their cats because of the potential for being infected by toxoplasmosis from their cat’s faeces in litter trays. There is a fear of transmission of T. gondii oocysts from faeces to person (hard to achieve). And an infection can harm a baby in the womb. So there’s a real danger here but it is a very, very slight risk.

In any case, Mexican scientists at Juarez University of Durango state, Mexico tried to determine the association of T. gondii with symptoms and signs of premenstrual syndrome. Four hundred and eighty-nine women (489) between the ages of thirty and forty participated. The authors of the study state, “Our study for the first time reveals a potential association of T. gondii infection with clinical manifestations of premenstrual syndrome”.

So we have to remember that the study found a “potential association”. This is not a definite link and clearly further research is required. And the number of participants was quite low. In fact, The Daily Mail reports that 150 women participated (the Irish News says it is 151) so there’s possibly an error in reporting by these newspapers.

The Daily Mail says that 10 of the women participating in the study were found to be carrying this parasitic protozoan and therefore were infected by toxoplasmosis – a small number. I am surprised that the researchers found it significant. It probably isn’t. We should remind ourselves that it is quite a common infection and is nearly always asymptomatic (without symptoms). And we should also remind ourselves that the most common cause of infection is not from cat faeces but by contaminated meats and vegetables.

How are people infected with toxoplasma
How are people infected with toxoplasma. Screenshot.

The researchers themselves admit that the study was small and that the findings need to be verified by further work. The fear that I have is that it may lead to the abandonment of domestic cats which is why I am making sure that people who read about this fully understand the conclusions of the study and don’t jump to incorrect conclusions.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

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
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.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Can cats be tested for toxoplasmosis?

Cats can be tested for toxoplasmosis. Serologic tests including ELISA (enzyme-linked immunosorbent assay) will show if a cat has been exposed to the disease. A positive test in a healthy cat signifies that the cat has acquired active immunity. Such a cat is not a source of human contamination. For the sake of clarity “serologic tests” means tests on the blood to look for antibodies which are created in response to an infection as part of the immune response.

\Rose a moggie cat
Rose, a moggie cat and a tortie-and-white cat. Photo copyright Helmi Flick.

Also, the finding of Toxoplasma gondii oocysts in a cat’s faeces indicates that the cat is currently infective (can cause an infection) to other cats and to people. This is a zoonotic disease. Coronavirus is also zoonotic.

As for symptoms of the illness, this disease is usually asymptomatic (i.e. without symptoms). When they are present the disease affects the lungs, lymphatic system, eyes, spinal-cord, and the brain. The most common symptoms are, rapid breathing, cough, lethargy and loss of appetite. There may also be neurological signs. Other symptoms may include swelling of the abdomen, diarrhoea, weight loss and fever. The lymph nodes may be enlarged and kittens may suffer from pneumonia, liver insufficiency and encephalitis.

My research, however, throws up some issues. Firstly, many cat with toxoplasmosis may also be concurrently suffering from feline immunodeficiency virus (FIV) or feline leukaemia virus ( FeLV).

Cornell state that the usual diagnosis of toxoplasmosis in cats is based upon a cat’s history and symptoms combined with laboratory tests. I refer to all of those above.

A positive serological test does not mean that toxoplasmosis is causing the signs of illness in a cat because as mentioned there may be concurrent illnesses and in any case most cases of toxoplasmosis in felines are asymptomatic as also mentioned.

Draco a glamorous moggie cat
A superb show moggy! Photo copyright Helmi Flick. This is a tabby. It is possible to show moggies at cat shows.

The conclusion that I can draw from this research is that it is possible to test cats for toxoplasmosis and you will have to see a veterinarian to do that. Your veterinarian will be able to add far more detail than I am able to do through research. This really is veterinarian’s work as it is quite complicated.

If you are considering a test because you have a cat and are about to have a child and are fearful about getting toxoplasmosis from your cat, it may be helpful if you read a page that I have written on this recently which is about getting toxoplasmosis from cat litter.


Sources: Reference books and authoritative websites but discuss it with your vet please.

There are many page about this disease on this site. Here are some recent ones:

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Does cat vomit contain toxoplasmosis?

This is a good question that had not occurred to me before I noticed that it is a Google search term. I interpret the question to mean, “Does cat vomit contain toxoplasma oocysts?”. I say this because human infection comes from ingesting T. gondii oocysts.

T. gondii oocyst
T. gondii oocyst. Illustration: PoC.

A cat becomes infected with T. gondii in two ways it seems to me.

Tissue cysts

Usually cats become infected when consuming an infected mouse which has the parasite’s cysts inside its tissues. The parasite goes into the cat’s stomach and survives and passes into epithelial cells of the cat’s small intestine where they undergo sexual development and reproduction. Large numbers of durable, thick-walled zygote-containing cysts known as oocysts are created. The epithelial cells rupture and the oocysts are shed in the cat’s faeces. A person may ingest these oocysts.

Fecal oocysts

The other way is when a cat ingests oocysts but cats are less likely to be infected in this way as they are “much less sensitive to oocyst infection than are intermediate hosts [such as rodents and livestock].

However, if a cat ingests oocysts and then vomits, for whatever reason, the oocysts will be in the vomit. If then an extremely rare and unfortunate chain of events takes place it is conceivable that a person could ingest some oocysts which would infect the person. The chain of events I envisage would be a person clearing up the vomit and getting some of it on their hands. They wash their hands poorly or not at all and then put their hands in their mouth.


My conclusion, subject to someone more expert contradicting me, is that cat vomit can contain toxoplasmosis in the form of T. gondii oocysts. Ask a vet about this and see what he says. I’d bet they don’t provide a clear answer. The lifecycle of toxoplasmosis is complex and confusing. Cats are the only known definitive hosts of this zoonotic disease. It is a parasite.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

USDA Fed Kittens with Toxoplasma-Infected Raw Meat Then Incinerated Them

The USDA fed kittens with Toxoplasma-infected raw meat then discarded them by incineration at 2-3 weeks of age having harvested toxoplasma oocysts.

In a letter written by Congressman Michael D. Bishop to the Secretary of Agriculture, US Department of Agriculture, he reveals to the world that the USDA have been breeding kittens in their hundreds over many years and feeding them with toxoplasma-infected raw meat so that scientists can harvest toxoplasma oocysts from their poop. They then incinerate them. The USDA protocol calls for the use of 100 kittens annually.

USDA Fed Kittens with Toxoplasma-Infected Raw Meat Then Incinerated the Kittens
This picture is said to have been taken inside the lab. The cat is not a kitten so I can’t vouch for the veracity of this image.

USDA’s Lack of Ethics

From my standpoint, and I believe I speak for the majority of American taxpayers, I don’t think you could envisage a more abusive form of animal testing than this. And it has been carried out by the USDA. Congressman Michael D. Bishop says that this is the very organization which has a responsibility to enforce animal welfare laws and regulations. He says that this government agency is treating animals with contempt and of course, if it is true, his statement is also true.

Please click on the pictures below to see them in a larger format and use the browser back arrow to return to this page. Thanks.

I am told by that an organization ‘White Coat Waste Project‘ discovered the experiments through a Freedom of Information Act request.

Research Project

Michael D Bishop was referring to a research project called “Toxoplasmosis in Cats”. It has been carried out at the USDA’s Animal Parasitic Diseases Laboratory in Beltsville, Maryland, USA. The project entails the breeding of hundreds of kittens and harvesting toxoplasma oocysts from them. The kittens are discarding by “incineration”.

Innacurate Reporting of Pain

In addition to the shocking news that Congressman Bishop’s letter brings to the general public, he also states that there has been inaccurate pain reporting by the USDA. Congressman Bishop states that the researchers “significantly under-reported the amount of pain and distress that will be caused to the kittens”.

Apparently, the pain reporting problems were corrected in 2017. However, a subsequent report indicates that the laboratory is still mis-categorizing the kittens as suffering from little or no pain or distress (pain category C).

Humane Alternatives?

The USDA argues that toxoplasmosis cannot be produced in a cell culture or by any other animal species. Mr Bishop asked whether the USDA have investigated more efficient and more humane alternatives to the use of kittens in producing toxoplasma oocysts.

Why Kill The Kittens?

Also, there is the outstanding question as to why the USDA did not adopt out the kittens. Of course, you could argue that the whole program is flawed and inhumane but if it must take place why aren’t the kittens adopted out to homes? The USDA admit that the kittens do not usually become sick and can be treated with a course of antibiotics.

Given this information, why are the kittens killed rather than treated and adopted out to taxpayers who are funding the research? Congressman Bishop asks whether the USDA have a policy or procedure for adopting out these kittens.

No Response To Query: USDA Fed Kittens with Toxoplasma-Infected Raw Meat and Incinerated Kittens

At the time of writing this, I understand that Mr Bishop and the online press including Fox5, which is the source of this article, are awaiting a response from the USDA.

I have published the letter on this page.

Please search using the search box at the top of the site. You are bound to find what you are looking for.

follow it link and logo