Latest news with #ToxoplasmaGondii
Telegraph
3 days ago
- 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.
The Sun
30-05-2025
- Health
- The Sun
New threat to plummeting male fertility rates identified as common but ‘silent' parasite that ‘DECAPITATES sperm'
FERTILITY rates appear to have been declining in both men and women globally - and now scientists have found a common single-celled parasite may be a contributor. Male fertility rates in particular have been plummeting over the past half-century, with an analysis from 1992 showing a steady decrease in sperm counts and quality since the 1940s. 3 3 And a more recent study found male infertility rates increased nearly 80 per cent from 1990 to 2019. Declining fertility rates have been attributed to a combination of factors, including rising costs associated with raising children. But now accumulating evidence suggests parasitic infections could also be a threat. A study published in April this year showed for the first time "human sperm lose their heads upon direct contact" with a parasite called Toxoplasma gondii. Toxoplasma gondii causes toxoplasmosis - an often harmless infection but can cause serious problems in individuals with weakened immune systems, pregnant women, and newborns. The parasite is found in the faeces of infected cats and in undercooked meat. Writing for The Conversation, Bill Sullivan, Professor of Microbiology and Immunology, Indiana University, said how the "new study bolsters emerging findings that underscore the importance of preventing this parasitic infection". Foodbourne transmission and animal to human transmission are the top ways people can get toxoplasmosis. Eating raw or undercooked meat, particularly lamb, pork, and venison, is a primary source of infection. And eating unwashed fruits and vegetables that have been contaminated with cat faeces or soil can also lead to infection. Major health advice for couples as HSE offers new resources for anyone struggling with fertility Ingesting the parasite through contact with cat faeces (poop) or soil contaminated with cat faeces is a common way to get toxoplasmosis. Cleaning cat litter boxes without proper hygiene can also expose people to the parasite. While toxoplasmosis is generally harmless for most people with healthy immune systems, often causing no symptoms or mild, flu-like symptoms that resolve on their own, Sullivan said toxoplasma remains in the body for life as dormant cysts in brain, heart and muscle tissue. And these cysts can reactive and cause additional episode of severe illness that damage critical organ system. He explains: "Between 30 per cent and 50 per cent of the world's population is permanently infected with toxoplasma due to the many ways the parasite can spread. "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. 3 "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." Evidence in past studies suggesting toxoplasma can reside in male reproductive organs has prompted analysis of fertility in infected men. In the April 2025 study, researchyers from Germany, Uraguay 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. Looking at what happens when the parasite comes into direct contact with human sperm in a test tube, they observed that after only five minutes, 22.4 per cent of sperm cells were beheaded. The number of decapitated sperm also increased the longer they interacted with the parasites. Sperm cells that maintained their head were often twisted and misshapen, and sperm cells had hole sin their head, suggesting the parasites were trying to invade them as it would any other type of cell. Sullivan added: "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." Could you have toxoplasmosis? Toxoplasmosis is a common infection that you can catch from the poo of infected cats, or infected meat. It's usually harmless but can cause serious problems in some people. Most people who become infected with the toxoplasma gondii parasite don't show any signs of infection. The parasite can reside in the body for life without causing issues. However, if you do have symptoms, they can be mild and flu-like, such as fever, swollen lymph nodes, and muscle aches. According to the NHS, some people may have more serious symptoms including: confusion blurred vision slurred speech unsteady walking Your GP may do blood tests to see if you've been infected with toxoplasmosis. They can also prescribe medicines to treat the infection if necessary. Most people who get toxoplasmosis get better without treatment. However, you'll usually be given medicines, including antibiotics, if you: are pregnant have a weakened immune system, for example, you're taking immunosuppressant medicines or you have HIV have symptoms affecting your eyes To avoid toxoplasmosis: wear gloves while gardening, and wash your hands thoroughly afterwards wash your hands before preparing food and eating wash hands, knives and chopping boards thoroughly after preparing raw meat wash fruit and vegetables thoroughly to get rid of any traces of soil thoroughly cook meat, especially lamb, pork and venison avoid cat poo in cat litter and soil if you can, wearing gloves if you need to empty cat litter trays and washing your hands afterwards Don't: eat raw or undercooked meat, or cured meats like salami or parma ham have unpasteurised goats' milk or any products made from it touch pregnant sheep or lambs do not feed cats raw or undercooked meat
