Latest news with #ToxoplasmaGondii
ABC News
6 days ago
- Health
- ABC News
Toxoplasmosis test could lead to learning how parasite affects behaviour
An international research team has developed an online test that they say is capable of detecting toxoplasmosis infection, commonly spread to humans by cats. While the test is not designed to replace a medical diagnosis, the researchers hope it will open the door for more large-scale studies into the effects of toxoplasmosis on the population. An estimated 30 to 50 per cent of the world's population is infected with Toxoplasma gondii, a single-celled parasite capable of infecting humans and any warm-blooded animal or bird. In Australia, the main host of the parasite is cats, which typically become infected by eating small mammals such as rodents or birds. The disease associated with the parasite, toxoplasmosis, can cause a range of health problems, from minor flu-like symptoms to, in rare cases, inflammation of the brain, seizures, and blindness. Toxoplasmosis can alter behaviour in animals, and some research suggests it may also affect how humans think. A new international study published in Acta Psychologica may provide a new way to study these effects. According to neuroeconomist Michele Garagnani, from The University of Melbourne and study co-author, toxoplasmosis affects our neurochemistry by influencing neurotransmitters such as dopamine, serotonin, and adrenaline, which regulate behaviour. Unlike many parasitic infections, being infected with T. gondi has been linked to a range of mental health conditions and behavioural changes, including bipolar disorder, delayed reaction times, and schizophrenia. The infection has been found to make mice impatient and willing to take risks. In some cases, mice actively seek out cats, which makes them more likely to be eaten. While it is still unknown how the parasite causes these changes, it raises important questions about the broader impacts of toxoplasmosis on human health and behaviour. "When we estimate that toxoplasmosis affects 2.4 billion people worldwide, that's a very large portion of the global economy who are having their decisions at least partially influenced by a parasite," Dr Garagnani said. Much about how toxoplasmosis affects human behaviour remains unknown. One major obstacle is that medical testing for the parasite is expensive and invasive, requiring blood or saliva samples. "Our research was trying to develop a method that is very cheap and easy to test on a large number of people," Dr Garagnani said. In the study, researchers ran a laboratory experiment with 79 participants with RhD-negative blood lacking the RhD protein on the surface of red blood cells, asking them to complete a reaction-time task. People with the RhD-negative blood type, about 20 per cent of Australians, have slower response times when infected by the parasite. While it is unclear why RhD-negative individuals have slower reaction times when infected, some theorise that the RhD antigen has protective capabilities against the parasite, and in its absence, patients experience elevated symptoms. Despite the small sample size, the team found that their method matched medical testing with 97 per cent accuracy. The delay in reaction time is small, between 0.16 and 0.25 seconds, but Dr Garagnani said even marginal effects could have large-scale consequences. "On a societal scale, having toxoplasmosis infection with that particular blood type leads to an increase in traffic accidents, for example," he said. The team then replicated the experiment using an online survey with more than 1,000 participants in the UK who had RhD-negative blood. Based on the results, the research team deemed 18 per cent of the respondents to be infected with toxoplasmosis. The team then asked participants a series of questions about their risk preferences, employment status, income, and completed other cognitive tests. "Those who were deemed infected were more likely to smoke, drink alcohol, and experience mental health problems such as anxiety, stress and depression compared to the non-infected participants," Dr Garagnani said. While the new online test does not replace a medical diagnosis, Dr Garagnani hoped it would allow researchers to measure the impact of toxoplasmosis on humans. "Our new method is an opportunity for the world as a whole to understand how many of us are infected, how it affects our behaviour, and what steps we can take to manage its impact," he said. Veterinary parasitologist Tharaka Liyanage said the study posed an innovative approach to exploring the potential behavioural consequences of an infection. "I find it fascinating that a microscopic cat parasite could influence not only human health, but also cognition, behaviour, and even economic decision-making," he said. "This tool may be particularly useful in low-resource settings or as a preliminary step in large-scale epidemiological studies." But, Dr Liyanage cautioned that a lot of work needed to be done before the tool made its way into a clinical setting. "I believe further validation, particularly in consultation with medical and clinical experts, would be necessary before this method can be considered for broader application." The test also requires people to have RhD-negative blood, which only 15 to 20 per cent of people have. Rima McLeod, an internationally recognised toxoplasmosis expert from the University of Chicago, echoed this sentiment and called for further research. "Proper, accurate serologic controls documenting toxoplasma infection or its absence for each participant would be needed to implicate toxoplasma in the associations they propose," Professor McLeod said. Dr Garagnani hoped to conduct further tests on the diagnostic tool. "We are hoping that with future study we verify further that the method works, and whether it could be used as a public policy type of intervention where we could firstly test for toxoplasmosis using our method and then try to understand how to effectively target the population where the prevalence is more diffuse."
Telegraph
04-08-2025
- Politics
- Telegraph
The greatest threat to our universities isn't funding or AI, it's China
I've been thinking a lot about a particular intestinal parasite called Toxoplasma gondii. Its goal is to enter the stomachs of cats. To achieve this, it infects rats, causing them to develop a 'fatal attraction' to the feline predators, which kill and consume them. Job done. This could be taken as a metaphor for much that is wrong with Britain. In the sybaritic decades since the Cold War, we have developed an infatuation with the very people and things that will devour us. It is a kind of cultural pathology. Consider universities. From Marxism to jihadism, every dogma that opposes Western values is seemingly not just indulged, but actively promoted by academics and embraced by students. I read English in the early noughties. The trend was underway then. Under the rubric of 'critical theory', we were taught to interpret all of literature as an allegory for postcolonialism, queer theory, deconstruction, feminism and Marxism (never conservatism or liberalism). Fast-forward to today and the Pride Progress flag flutters above my old college. Keffiyeh-clad students – frequently lecturers, too – demand the toppling of statues and raise hell in venerable quads in support of the very ideologies that would deprive them of their freedoms. This cultural Toxoplasma gondii was particularly in evidence this week, when new university free speech rules were announced by the Department for Education. These aim to bar overseas regimes from vetting staff employed at British universities, in an effort to fight 'any attempt by a foreign state to intimidate, harass or harm individuals in the UK'. The measures are understood to particularly affect Confucius Institutes, which are partnerships between British and Chinese universities. Funded by an arm of the Chinese state, they offer tuition in Mandarin and cultural activities at 20 universities, including Manchester, Coventry and Liverpool. They have long been accused of acting as a sinister Trojan horse for the Chinese Communist Party (CCP). According to the charity UK-China Transparency, Chinese Confucius Institute staff are vetted by CCP apparatchiks for their 'political attitude' before being appointed to work in Britain. Once on our shores, they are said to 'impose state-sponsored discipline' on Chinese students and 'conduct harassment'. Is it a coincidence that the engine of Chairman Mao's cultural revolution was China's youth, with the Red Guards paramilitary movement led by a vanguard of students? Given these concerns, the new regulations would seem long overdue. But how did the Toxoplasma university officials respond? To defend the Confucius Institutes, of course. To be fair to them, the Middle Kingdom is a cash cow. Astonishingly, more than a quarter of our students are now Chinese, and they pay far higher rates than British youngsters. But this only proves that the problem extends to generations of government, which created the financial model that encouraged such dependency. Last year it emerged that, after becoming apparently compromised by an alleged Chinese spy, Prince Andrew got rather too close for comfort to the regime in Beijing, even sending an annual birthday letter to President Xi. At the time, there was a great appetite for the story. Not only was it scandalous, but it concerned the member of the Royal Family that – after that Emily Maitlis interview – the public loves to hate. The true implications of the revelations, however, were less widely appreciated. Prince Andrew was not simply an anomalous case, distinguished by his gullibility and desperation. He was symbolic of growing Chinese influence over many aspects of British officialdom. Future generations will surely marvel at the enthusiasm with which we enabled our destruction. If they still have the freedom to do so, of course.
Yahoo
23-06-2025
- Health
- Yahoo
Cat Parasite Can Seriously Disrupt Brain Function, Study Suggests
Infection with a common parasite can seriously disrupt the brain function of intermediate hosts – potentially including humans – new research has found. Even when the number of neurons affected is relatively small, toxoplasmosis – infection with the parasite Toxoplasma gondii – strongly interferes with neuronal communication. That's revealed by a study involving mouse brain cells, some grown in a dish and some collected from living animals. Neurons infected with the parasite release fewer extracellular vesicles (EVs), tiny lipid-bound packets of proteins, nucleic acids, and metabolites that are used as a means of intercellular communication. It's a finding that carries a lot of weight in the debate on the behavioral impact of toxoplasmosis. Related: Parasites May Be Hijacking Evolution on Planet Earth "We found this disruption in EV signaling can interfere with how neurons and glial cells, especially astrocytes, maintain a healthy brain environment," says parasite immunologist Emma Wilson of the University of California Riverside School of Medicine. "Even a handful of infected neurons can shift the brain's neurochemical balance. This suggests that communication between neurons and supporting glial cells is not only critical, but also vulnerable to hijacking by parasites." T. gondii is a parasite known for wreaking behavioral changes – for better or worse – in its hosts. It likes to find a cell and nestle inside, and the types of cells it likes most are neurons, crossing the blood-brain barrier to get there. Once inside, the protozoan can hunker down for decades, just hanging out. It's one of the most successful parasites on the planet, and there are few warm-blooded species it can't invade. However, it can only reproduce in cats; research suggests that some of the behavioral changes exhibited by infected organisms are to force them into an increased likelihood of encountering cats, such as rodents suddenly wanting to seek out the smell of cat pee instead of avoiding it. Some studies have found that the evidence for such behavioral manipulation is circumstantial, and that we can't conclusively link these changes to the parasite. It's especially complicated for humans; behavior is complex, and it's difficult to attribute changes to any one cause. The new study isn't behavioral, but entirely based on physical evidence. The researchers infected mouse neurons with T. gondii, and carefully analyzed the production and content of EVs, comparing it against EV production in healthy, uninfected neurons. They found that not only was EV production reduced, the content of the packets was altered compared to those produced by healthy neurons. Since the role of EVs is to relay information between neurons and astrocytes, this had a knock-on effect: the astrocyte gene expression was also altered, resulting in increased production of specific immune signatures, and a decrease in a transporter that helps remove excess glutamate from the brain. Excess glutamate is linked to problems such as seizures and neural damage, complications that are known to arise from severe cases of toxoplasmosis. This suggests that we might be underestimating the impact of T. gondii. "The parasite may play a larger role in neurological and behavioral conditions than we previously thought," Wilson says. A shockingly large number of humans harbor T. gondii. It's mostly contracted from ingesting poorly prepared food, such as undercooked meat, or from interacting with cat feces. Prevalence rates reach as high as 80 percent in some parts of the world; in the US, an estimated 10 to 30 percent of the population is infected. Most people will never know about their little neural hitchhikers and will sail through life unaffected, but for some people – particularly infant, elderly, immunocompromised, and pregnant people – infection can become dangerous. The most effective prevention tools are to cook your meat thoroughly, wash your vegetables, and wash your hands carefully after handling kitty litter. Meanwhile, research such as Wilson's may help us better understand the parasites, and work on ways of protecting ourselves. "Our brains have built-in defenses that may recognize and respond to neurons infected by T. gondii," she says. "If we can learn how to support or enhance that process, we may be able to better protect people, especially the most vulnerable." The research has been published in PLOS Pathogens. New Treatment May Cure Severe Type 1 Diabetes, Study Finds Scientists Identify New Blood Group, And It's The World's Rarest Extreme Heat Wave Scorches The US: Here's How You Can Stay Safe
Telegraph
18-06-2025
- Health
- Telegraph
Could the answer to the male fertility crisis be lurking in your cat's litter tray?
It may come as a surprise but there's about a one-in-three chance that a parasite for which there is no cure has invaded your body and is lying dormant inside you. Your chances of having picked it up are higher if you have a cat, as the parasite only reproduces inside the feline intestinal tract and its eggs end up in the litter tray, or wherever else your pet does its business. From there, it spreads through the environment to other animals, including ones we eat, so those partial to a steak tartare ought to be careful too. Yet there is no reason to panic. The vast majority of people infected with Toxoplasma gondii, the single-celled organism that causes toxoplasmosis, will never know they've had it. It can be dangerous to pregnant women and the people with compromised immune systems. But for the rest of us, any symptoms that do emerge tend to be mild and flu-like – unless you're a sperm. A growing body of evidence suggests toxoplasma gondii may be contributing to a dramatic global decline in male fertility counts. The discovery came by accident. Dr Zahady Velásquez, a researcher from the Institute for Parasitology at the University of Giessen in western Germany, was investigating how toxoplasma takes control of cells when she peered into her microscope and saw what looked like the aftermath of an execution. Dozens of sperm lay dismembered in the petri dish. They had clearly been decapitated after coming into contact with toxoplasma. 'The first thing that I saw was a lot of heads and tails,' she said of the scene. Dr Velásquez's initial reaction was that something had gone awry with the experiment. 'I thought: 'Oh my god, I did something wrong!',' she told The Telegraph. When it happened again, she decided to consult with a colleague who persuaded her that something interesting was going on. Then the work began. Sperm samples were exposed to the single-celled parasite for differing lengths of time, and the damage done was measured. After just five minutes in a test tube with the parasite, almost a quarter (22.4 per cent) of the sperm had been decapitated, and the number of beheadings rose the longer the sperm were exposed. Some of the sperm that survived were left misshapen and scarred by the encounter, their tails curled up or bent at right angles. Others bore characteristic puncture wounds to their heads suggesting the toxoplasma had tried to invade them in the same way they do other cells. The researchers also carried out experiments on mice and found that the toxoplasma were able to reach the testes and epididymis – the coiled tube at the back of the testicle where the sperm are stored – within two days of infection. It is the Toxoplasma gondii's mostly benign relationship with its hosts and ability to infect almost every warm-blooded animal on Earth that explains why toxoplasma has been so successful. However, the new research suggests that the parasite may just be acting slowly. The findings, coupled with the high prevalence of the parasite in the global population, suggest toxoplasma could be having 'an underappreciated impact on male fertility,' the researchers conclude in their report, which was published in the Federation of European Biochemical Societies journal in April. For years scientists have been grappling with an apparent crisis in male fertility, particularly after a 2017 meta-analysis (a statistical technique for combining the results of multiple studies) estimated that global sperm counts had fallen by 59 per cent since 1973. To be clear, this is a separate issue from declining birth rates. While the belief that civilisation faces oblivion because people are no longer interested in having children is currently in vogue, in fact, a range of factors including the high cost of parenthood and housing, as well as fears for the future, are to blame for declining birth rates, a recent major UN study found. The issue of sperm counts is similarly controversial. The reason behind the decline has so far eluded scientists. Numerous culprits have been put forward, from pollution, microplastics, food additives, obesity and even radiation emitted by mobile phones and microwaves. The discovery by Dr Velásquez and her colleagues has helped to open up a new line of enquiry, building on a handful of previous studies that suggested a correlation between toxoplasma infection and male infertility. A 2002 study in China, for instance, found that infertile couples were almost three times more likely to have a toxoplasma infection than fertile couples, while a 2005 study, also in China, found that sterile men were more likely to be infected. 'There's enough evidence out there from different independent labs across the world to pique my interest,' said Dr Bill Sullivan, a professor of pharmacology and microbiology at the Indiana University School of Medicine. 'I think we need to be vigilant and look at every possibility – because it's probably not just one thing,' he told The Telegraph. 'I think it's worthy of further investigation.' Dr Velásquez agrees: 'I really love our results, but I believe that [toxoplasma] is not the only issue that is inducing infertility in men. 'You need to consider that the diet that we have now is deficient in a lot of different minerals and vitamins, also the stress that we live in every day [...] we are not sleeping enough. It's a really big package and I believe that Toxo is just one part of it.' The discovery by Dr Velásquez and her team is the latest in a series of surprising findings about Toxoplasma. Studies have shown that infected mice lose their fear of cats, making them more likely to become prey, as the parasite causes inflammation in parts of the brain that process anxiety. Dr Velásquez is currently applying for grants for further research into the effects toxoplasma have on sperm. Of particular interest is the extent to which the parasite can interfere with sperm production while it is in its dormant stage. After spreading around the body, the organism forms cysts that can survive for long periods within the tissue of the host, including in the testes but also muscle tissue, the heart and the brain. It's these cysts that are excreted by infected cats, and that then find their way into the bodies of other mammals, including grazing cattle, sheep and domestic cat owners. The 'spy in your body' In another sign of how widespread the parasite is, a recent study from the UK suggested that 80 per cent of all sheep in the country carried the infection. While most people can easily overcome the initial infection and force the parasite into dormancy, removing these cysts entirely and ridding the body of the infection has so far proved impossible, largely because the parasite is so similar to the cells it infects, said Dr Velásquez. 'The Toxo, in this case, is like a spy in your body. It's exactly like your cells – they have almost exactly the same proteins inside, they do division as our cells do. So if I try to cut the life of the parasite, I'm probably going to affect your body a lot, and I could kill you.' Blood tests can identify whether a person has a latent toxoplasma infection which, as it can be passed from mother to child, can pose a serious threat to pregnant women. The parasite, in its active phase, can cause miscarriages and birth defects. People with compromised immune systems are also at risk. When the immune system goes down, the dormant parasite can reawaken and attack the body, leading to serious complications – a particularly sinister feature of the parasite that came to the fore during the height of the Aids epidemic. 'There's no cure to get rid of the tissue cysts that could be in your brain and your heart, and those are like time bombs ready to go off if your immune system should falter,' said Dr Sullivan. For the time being our best course of action to mitigate against the spread of the infection is by fostering greater awareness. 'Educational measures have gone a long way to diminish seroprevalence in more developed countries that are aware of the problem,' said Dr Sullivan. 'In France, the seroprevalence in the past was upwards of 80 to 90 per cent – an outrageous number [which] was believed to be through the consumption of a lot of rare meat, steak tartare, for example,' he said. But thanks to educational campaigns and improvements to food hygiene, rates of infection have come down to about 50 per cent. 'Still a huge number, but almost cut in half.' And what about pet cats? Should we be more careful about sharing our homes with these carriers of the parasite? 'There's certainly an element of risk that people need to be aware of in taking care of cat waste properly. But you certainly don't need to throw the baby out with the bathwater, so to speak. You don't need to get rid of your cat.' In its advice for avoiding toxoplasmosis, the NHS recommends wearing gloves when emptying your cat's litter tray and washing your hands afterwards. You should also wear gloves while gardening, thoroughly cook meat 'especially lamb, pork and venison' and wash fruit and vegetables thoroughly. Dr Velásquez would like to see more attention given to the potential effects of toxoplasma infection on male fertility. We know that it can be dangerous for pregnant women, but no one is paying attention to how it could affect men, she said. In some countries, including Austria, France and Uruguay, pregnant women undergo mandatory screening to detect Toxoplasma. But most countries do not test for it in women and none test for it in men, meaning families around the world are having children without ever knowing whether they carry the parasite, potentially putting themselves and their offspring at risk. 'When I was pregnant in Chile, we didn't have any test for us to know – but probably I was infected,' she said. 'I'm a little bit scared now, because what happens if it's in my brain?'
Gizmodo
30-05-2025
- Health
- Gizmodo
This Cat Poop Parasite Can Decapitate Sperm—and It Might Be Fueling Infertility
Male fertility rates have been plummeting over the past half-century. An analysis from 1992 noted a steady decrease in sperm counts and quality since the 1940s. A more recent study found that male infertility rates increased nearly 80% from 1990 to 2019. The reasons driving this trend remain a mystery, but frequently cited culprits include obesity, poor diet, and environmental toxins. Infectious diseases such as gonorrhea or chlamydia are often overlooked factors that affect fertility in men. Accumulating evidence suggests that a common single-celled parasite called Toxoplasma gondii may also be a contributor: An April 2025 study showed for the first time that 'human sperm lose their heads upon direct contact' with the parasite. I am a microbiologist, and my lab studies Toxoplasma. This new study bolsters emerging findings that underscore the importance of preventing this parasitic infection. The many ways you can get toxoplasmosis Infected cats defecate Toxoplasma eggs into the litter box, garden or other places in the environment where they can be picked up by humans or other animals. Water, shellfish and unwashed fruits and vegetables can also harbor infectious parasite eggs. In addition to eggs, tissue cysts present in the meat of warm-blooded animals can spread toxoplasmosis as well if they are not destroyed by cooking to proper temperature. While most hosts of the parasite can control the initial infection with few if any symptoms, Toxoplasma remains in the body for life as dormant cysts in brain, heart and muscle tissue. These cysts can reactivate and cause additional episodes of severe illness that damage critical organ systems. Between 30% and 50% of the world's population is permanently infected with Toxoplasma due to the many ways the parasite can spread. Toxoplasma can target male reproductive organs Upon infection, Toxoplasma spreads to virtually every organ and skeletal muscle. Evidence that Toxoplasma can also target human male reproductive organs first surfaced during the height of the AIDS pandemic in the 1980s, when some patients presented with the parasitic infection in their testes. While immunocompromised patients are most at risk for testicular toxoplasmosis, it can also occur in otherwise healthy individuals. Imaging studies of infected mice confirm that Toxoplasma parasites quickly travel to the testes in addition to the brain and eyes within days of infection. In 2017, my colleagues and I found that Toxoplasma can also form cysts in mouse prostates. Researchers have also observed these parasites in the ejaculate of many animals, including human semen, raising the possibility of sexual transmission. Knowing that Toxoplasma can reside in male reproductive organs has prompted analyses of fertility in infected men. A small 2021 study in Prague of 163 men infected with Toxoplasma found that over 86% had semen anomalies. A 2002 study in China found that infertile couples are more likely to have a Toxoplasma infection than fertile couples, 34.83% versus 12.11%. A 2005 study in China also found that sterile men are more likely to test positive for Toxoplasma than fertile men. Not all studies, however, produce a link between toxoplasmosis and sperm quality. Toxoplasma can directly damage human sperm Toxoplasmosis in animals mirrors infection in humans, which allows researchers to address questions that are not easy to examine in people. Testicular function and sperm production are sharply diminished in Toxoplasma-infected mice, rats and rams. Infected mice have significantly lower sperm counts and a higher proportion of abnormally shaped sperm. In that April 2025 study, researchers from Germany, Uruguay, and Chile observed that Toxoplasma can reach the testes and epididymis, the tube where sperm mature and are stored, two days after infection in mice. This finding prompted the team to test what happens when the parasite comes into direct contact with human sperm in a test tube. After only five minutes of exposure to the parasite, 22.4% of sperm cells were beheaded. The number of decapitated sperm increased the longer they interacted with the parasites. Sperm cells that maintained their head were often twisted and misshapen. Some sperm cells had holes in their head, suggesting the parasites were trying to invade them as it would any other type of cell in the organs it infiltrates. In addition to direct contact, Toxoplasma may also damage sperm because the infection promotes chronic inflammation. Inflammatory conditions in the male reproductive tract are harmful to sperm production and function. The researchers speculate that the harmful effects Toxoplasma may have on sperm could be contributing to large global declines in male fertility over the past decades. Preventing toxoplasmosis The evidence that Toxoplasma can infiltrate male reproductive organs in animals is compelling, but whether this produces health issues in people remains unclear. Testicular toxoplasmosis shows that parasites can invade human testes, but symptomatic disease is very rare. Studies to date that show defects in the sperm of infected men are too small to draw firm conclusions at this time. Additionally, some reports suggest that rates of toxoplasmosis in high-income countries have not been increasing over the past few decades while male infertility was rising, so it's likely to only be one part of the puzzle. Regardless of this parasite's potential effect on fertility, it is wise to avoid Toxoplasma. An infection can cause miscarriage or birth defects if someone acquires it for the first time during pregnancy, and it can be life-threatening for immunocompromised people. Toxoplasma is also the leading cause of death from foodborne illness in the United States. Taking proper care of your cat, promptly cleaning the litter box and thoroughly washing your hands after can help reduce your exposure to Toxoplasma. You can also protect yourself from this parasite by washing fruits and vegetables, cooking meat to proper temperatures before consuming and avoiding raw shellfish, raw water and raw milk. Bill Sullivan, Professor of Microbiology and Immunology, Indiana University. This article is republished from The Conversation under a Creative Commons license. Read the original article.
