Latest news with #toxoplasmosis
ABC News
7 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."
Daily Mail
26-06-2025
- Health
- Daily Mail
100m Americans infected with parasite that 'silently' eats away at the brain... the subtle signs YOU have it
Alarming findings show that potentially more than 100 million Americans have been infected with a parasite that silently eats away at the brain. A new study by scientists at the University of California, Riverside, estimates that 10 to 30 percent of people in the US are infected with Toxoplasma gondii (T. gondii), often without knowing it. Previous studies have linked it to mind-altering behavior, such as risk-taking, depression and even schizophrenia. The parasite, which can lie dormant in the brain for decades, is typically contracted through undercooked meat or exposure to cat feces. Most people infected with Toxoplasma gondii experience no symptoms. When symptoms do occur, they often resemble those of the flu, such as fever, swollen lymph nodes, muscle aches, and fatigue, as well as confusion, poor coordination and muscle weakness. Because it typically mimics more benign conditions, the infection is often overlooked, but can be diagnosed via blood tests that look for antibodies. The milder symptoms usually subside within a few weeks with the help of anti-parasitic medicines or antibiotics, but in individuals with weakened immune systems, pregnant women, and infants, toxoplasmosis can cause more severe complications such as seizures and difficulty breathing. Now, based on their research, the scientists believe they have potentially found a way to detect T. gondii and treat it. The team discovered infected neurons in the brain release fewer extracellular vesicles (EVs) — particles that play a role in communication between cells. Lead researcher Emma Wilson, professor of biomedical sciences, said: 'Our research opens the door to using EVs as biomarkers, which can be isolated from blood.' Current diagnostic tools can only confirm if someone has been exposed to T. gondii by identifying antibodies, proteins produced by the body's immune system to fight foreign invaders like bacteria and viruses. However, tests cannot detect if the parasite is still active in the brain or how it might be impacting brain function. Wilson and her team are now conducting further research to better understand how the parasite operates in a bid to develop new therapies to clear the parasite or even vaccines in the future to protect against it. In humans, T. gondii can lead to toxoplasmosis, which causes flu-like symptoms that can go largely unrecognized. Pregnant women who ingest the parasite in early pregnancy can suffer a miscarriage or stillbirth, according to studies. Most infections go away without treatment but medication is available for those who are more at risk of serious complications. The researchers behind the most recent study say that there is 'no need to avoid someone who is infected [and] most people live their entire lives without symptoms'. But there are signs it could be linked to brain damage. Studies suggest patients infected with T. gondii were almost 50 percent more likely to have been diagnosed with schizophrenia than those without, for example. Offering advice in terms of avoiding infection, researchers behind the new paper added: 'The most effective prevention is proper food handling and hygiene. 'Cook meat thoroughly, wash vegetables, and always wash your hands after handling cat litter, especially from young cats, which are more likely to shed the parasite.'
Daily Mail
26-06-2025
- Health
- Daily Mail
Alarm over brain-eating parasite found in supermarket salad item - amid rise in deadly food poisoning
Health chiefs have sounded the alarm over ready-to-eat salad bags due to potentially-deadly contamination fears, amid an alarming rise in food poisoning outbreaks. There are currently no mandatory surveillance for bacteria in fresh produce—which can cause severe brain damage and breathing difficulties—despite ready-to-eat items surging in popularity, scientists have warned. The contamination is not confined to a specific area, instead reported across 10 European countries including the UK, the study, published in the journal Eurosurveillance found. Scientists collected 3,320 salad samples between October 2021 and September 2022 and found that over 4 per cent of the leaves were contaminated with toxoplasma gondii oocysts. This bacteria can be passed on by digesting cat feces, which contaminate food and water, making salad that is not washed properly a popular breeding ground for the bacteria. Research by the National Institute of Health suggests that half of the UK population show signs of past infection by the age of 50, though most cases go unnoticed. The nasty bug can also cause flu-like symptoms and muscle aches and pains. However, it can be fatal. People who have a weakened immune system, such as cancer patients, are at an increased risk of infection, known as toxoplasmosis. This can cause severe neurological and respiratory systems which can be fatal, causing damage to the brain, eyes, heart and lungs. Catching this infection during pregnancy can be particularly dangerous, resulting in spontaneous miscarriage and fetal abnormalities, the NHS warns. If people become seriously ill, they may need hospital care because the damage can be life-threatening. The NHS advises anyone who experiences more serious symptoms, including confusion and slurred speech to call 999. However, most cases will clear up on their own or can be treated with a course of antibiotics. Samples of the leaves were collected in the Czech Republic, Denmark, France, Germany, Italy, Norway, Poland, Portugal, Spain and the UK. Most positive samples were collected in winter and packaged in the UK, France, Portugal, Spain and Denmark. Scientists are now urging for better control measures to help protect consumers against infection. 'This is particularly relevant since ready-to-eat salads are intended to be consumed raw without any further treatment by the consumer', they added. 'Future work should investigate presence of [the parasite] in different steps of the ready-to-eat production to minimise infection risk for humans.' This comes as health watchdogs warn that outbreaks of food poisoning are becoming more complex, with a significant increase in serious cases. In April this year, health officials sounded the alarm over a worrying surge in serious cases of a rare strain of bacterial infection that's been linked to colon cancer. The outbreak sickened 288 patients, causing nine cases of haemolytic uremic syndrome (HUS) — a life-threatening condition that can lead to kidney failure —and two deaths, the latest UKHSA figures show. Food safety chiefs previously said they were confident a type of butterhead lettuce, named Apollo, was behind the outbreak of the diarrhoea-causing bug. Experts believe lettuce's texture can make it more prone to the bacteria and the fact it's not cooked, which would usually kill off bugs, increases the risk. Rates of a rare strain of the bug commonly in contaminated lettuce—have risen almost 10-fold in England in just seven years, fresh figures show. Cases of the infection are thought to be linked to the mysterious epidemic of colon cancer among the under 50s. In 2023 alone, the Food Standards Agency (FSA) investigated 59 new or ongoing outbreaks and incidence of gastrointestinal illness linked with foodborne disease. Now, experts have told of the potential reasons behind the explosion — including climate change, more vigilant reporting by hospitals and a rise in the number of people vulnerable to severe illness. It may also be the case that more shoppers are opting for prime sources of the bug, such as lettuce, either via ready made sandwiches or bagged salads. Studies suggest leafy greens are responsible for half of all outbreaks. Professor Paul Hunter, a renowned infectious diseases expert from the University of East Anglia told MailOnline: 'Watering during growth allows the potentially contaminated water to rest on the lettuce leaf. 'The rough and waxy surface of the leaf also makes it difficult to wash off E. coli. 'As to whether E. coli can enter the tissue of the lettuce, probably it can, though the evidence is somewhat conflicting. 'The main risk comes from bacteria attached to the leaf surface. Most other vegetables are either peeled or cooked before eating. 'We also found bagged lettuce already prepared for use to be a common factor.' Experts say all salad should be washed thoroughly by immersing in cold water. Storage of vegetables is also key: if salad bags are in the fridge and the temperature is less than four degrees, bacteria will not multiply as rapidly. Experts also say recent wet, warm weather can creates an 'ideal' breeding ground for E. coli to spread. Out of the 436 recorded incidence involving food contamination, Salmonella was the most recorded cause, with Listeria and STEC also on the rise. STEC is one of the most dangerous forms of food-borne E. coli, capable of causing life-threatening kidney failure, serious blood clotting disorders.
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?'
