Latest news with #Centrocestusformosanus
Yahoo
3 days ago
- General
- Yahoo
California fish carry human-infecting parasites that can cause stroke or heart attack, researchers find
More than 90 percent of popular freshwater game fish in Southern California contain a parasite that is capable of inducing strokes or heart attacks in the humans who eat them. Researchers said the parasites were two species of flatworms known as trematodes. At no more than a few centimeters in length, the flukes – a class of flatworms – can result in weight loss or lethargy. Although rare, infection has also resulted in more severe consequences. 'Americans don't usually think about parasites when they eat freshwater fish because it hasn't historically been an issue here,' Ryan Hechinger, an ecologist and parasitologist at UC San Diego's Scripps Institution of Oceanography, said in a statement. 'But these trematodes have now been widely introduced in the U.S. and that means that doctors and the public should be aware.' He is the senior author of the study which was published Tuesday in the Journal of Infectious Diseases. It was funded by the National Institutes of Health. To identify this issue, Hechinger, the University of Nebraska's Daniel Metz, and former Scripps graduate student and Smithsonian Environmental Research Center marine scientist Emma Palmer examined 84 fish from seven different species in 2023. Those fish included largemouth bass and bluegill, which were collected from five frequented fishing locations in San Diego County. Of those, 93 percent were infected with the Haplorchis pumilio parasite, and some were the host to thousands. Two of the five locations yielded positive results for the second parasite known as Centrocestus formosanus, which occurred in 91 percent of the fish. Historically, the trematodes have infected people in Southeast Asia and likely arrived in the U.S. more than a decade ago inside an invasive aquatic snail known as the red-rimmed melania. That snail is found in 17 states and Puerto Rico. Previous work led by Hechinger had found that the red-rimmed melania and its parasites are widespread in the Golden State. So, what is the risk to Californians and Americans at large? Hechinger says there haven't been any reported cases of parasites infecting Americans yets, but 'nobody is looking for cases and doctors aren't required to report them.' Californians should make sure to monitor fish advisories for any changes. The risks posed by them are easy to avoid as, if you fully cook your fish or freeze any that's intended to be eaten raw for at least a week, the parasites will die. Although, the authors found that many Americans are likely consuming freshwater fish without taking the proper precautions. The greatest health threats come from repeated infection over many months or years. Foodborne trematode infections cause two million life years lost to disability and death worldwide every year, according to the World Health Organization. They recommend that fish-borne trematode infection be added to the list of diseases doctors are required to report to public health officials. 'These parasites are here in the U.S., and they're infecting fish that people are eating,' said Hechinger. 'We hope this study can help make public health officials, doctors and the public more aware.'
Newsweek
3 days ago
- General
- Newsweek
People in California Warned Over Parasite-Riddled Fish
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. Southern Californians have been warned that more than 90 percent of popular game fish have been found to contain invasive, parasitic worms that can infect humans. Two species of the parasitic flatworms known as "trematodes" were found infecting five species of freshwater fish from San Diego County in a study by researchers from University of California, San Diego's Scripps Institution of Oceanography. Infection with the worms typically causes gastrointestinal problems, lethargy and weight loss in humans—but severe cases have even been known to cause heart attack and strokes. "Americans don't usually think about parasites when they eat freshwater fish because it hasn't historically been an issue here," said paper author and ecologist Ryan Hechinger in a statement. However, he added: "These parasites are here in the U.S., and they're infecting fish that people are eating. "We hope this study can help make public health officials, doctors and the public more aware." This bluegill analyzed by the team (main) was found to contain 16,973 'Haplorchis pumilio' parasitic worms (inset) This bluegill analyzed by the team (main) was found to contain 16,973 'Haplorchis pumilio' parasitic worms (inset) Emma Palmer / Hudson Pinto In their study, the researchers sampled 84 fish—representing seven species, including largemouth bass and bluegill—from five popular fishing spots around San Diego County. The team identified two species of invasive trematode in the fish: Haplorchis pumilio and Centrocestus formosanus. H. pumilio was found in 93 percent of all fish sampled—with some individual fish harboring thousands of the parasitic worms. C. formosanus, meanwhile, occurred in 91 percent of the fish from two of the locations. Both worms are believed to have arrived in the U.S. from Southeast Asia more than a decade ago, traveling inside the bodies of one of their hosts—an invasive aquatic species known as the Malaysian trumpet snail (Melanoides tuberculata.) Today, M. tuberculata can be found in 17 states, as well as Puerto Rico—and both it and its parasites are widespread in California. The worms have a life cycle that involves living inside three hosts: first, the trumpet snail; then, a fish; and finally a warm-blooded vertebrate like birds or humans that are unlucky enough to eat the infected fish. Hechinger said there is "no need to panic," as the risk from the parasites can be neutralized by either cooking the fish or, if planning to consume them raw, freezing for at least one week beforehand. A survey of social-media videos conducted by the team alongside their field work, however, revealed that some Americans are consuming freshwater fish raw without these precautions—putting them at risk of infections. "Nearly 5 million views shows there is widespread interest and possibly a widespread practice of folks eating freshwater fish raw," said paper author and marine scientist Emma Palmer of the Smithsonian Environmental Research Center in a statement. Palmer conducted the research into the parasites while undertaking her graduate studies at the Scripps Institution of Oceanography. Stock image: A Malaysian trumpet snail ('Melanoides tuberculata') is seen on a white background. Stock image: A Malaysian trumpet snail ('Melanoides tuberculata') is seen on a white background. Marlonneke/iStock / Getty Images Plus It is unclear what impact the invasive worms might be having on the fish connoisseurs of Southern California, the researchers said. "There haven't been any reported cases of these parasites infecting Americans, but nobody is looking for cases, and doctors aren't required to report them," said Hechinger. He added: "This kind of research is so important to identifying new public health threats." Based on their findings, to better track the parasites, the researchers have recommended that these fish-borne worm infections be added to the list of diseases that doctors are required to report to public-health officials. Do you have a tip on a science story that Newsweek should be covering? Do you have a question about astronomy? Let us know via science@ Reference Palmer, E. M., Metz, D.C.G., & Hechinger, R. F. (2025). Further Evidence for Plausible Transmission of Fishborne Trematodiases in the United States: Game Fish Carry Human-Infectious Trematodes and Are Eaten Raw. The Journal of Infectious Diseases.
Yahoo
3 days ago
- General
- Yahoo
California freshwater fish carrying invasive parasitic worms: Study
More than 90 percent of popular Southern California freshwater game fish sampled in a new study contained invasive worms capable of infecting humans, scientists warn. The parasites — two species of flatworms called trematodes — may pose a previously unrecognized public health risk in the United States, according to the study, published Tuesday in the Journal of Infectious Diseases. In Southern California, these trematodes are 'introduced parasites,' or parasites transported to a new place by an alien host. They often cause gastrointestinal problems, weight loss and lethargy in people — and in more severe cases, strokes or heart attacks, the authors noted. 'Americans don't usually think about parasites when they eat freshwater fish because it hasn't historically been an issue here,' said senior author Ryan Hechinger, an ecologist and parasitologist at the University of California San Diego's Scripps Institution of Oceanography, in a statement. 'But these trematodes have now been widely introduced in the U.S. and that means that doctors and the public should be aware,' Hechinger added. The two trematodes of focus in this study, Haplorchis pumilio and Centrocestus formosanus, likely arrived in the U.S. from Southeast Asia more than a decade ago, according to the study. They presumably did so via the bodies of one of their hosts: an invasive aquatic snail, the red-rimmed melania, which has now spread to 17 states and Puerto Rico. The parasites first move into the snails, which are then consumed by fish — leading them finally to the dinner plate of a warm-blood vertebrate, such as a human or a bird, the authors explained. While previously work led by Hechinger demonstrated the prevalence of red-rimmed melania and the trematode parasites across California, this research aimed to show whether fish that Americans enjoy consuming contains the parasites. To answer this question, Hechinger and his colleagues examined 84 fish across seven species, including largemouth bass and bluegill, from five fishing spots in San Diego County. Ultimately, they discovered that 93 percent of all fish included in the study were infected with the first trematode, Haplorchis pumilio. The second parasite, Centrocestus formosanus, was present at two of the five locations, occurring in 91 percent of those fish, per the study. 'These parasites are here in the U.S., and they're infecting fish that people are eating,' Hechinger said. 'We hope this study can help make public health officials, doctors and the public more aware.' At the same time, Hechinger emphasized that there is 'no need to panic,' as the dangers posed by the parasites can be prevented by fully cooking fish or freezing any fish intended to be consumed raw for at least a week. However, the scientists noted that a social media survey they included in the study showed that Americans may be eating freshwater fish without taking such precautions. Doing so, they warned, can raise the odds of infection considerably. In their survey, which included 125 YouTube videos with a total of nearly 5 million views, the scientists noted that 65 percent made no mention of proper cooking procedures. Going forward, the study authors said they intend to share their results with local public health officials to raise awareness. They expressed hope that their findings would reach medical practitioners, who might not immediately think of trematodes as a possible cause of gastrointestinal infections and other illnesses. The researchers also recommended that fish-borne trematode infection be included on the list of diseases doctors are required to report to public health agencies. 'There haven't been any reported cases of these parasites infecting Americans,' Hechinger said. 'But nobody is looking for cases and doctors aren't required to report them,' he added. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
The Hill
3 days ago
- General
- The Hill
California freshwater fish carrying invasive parasitic worms: Study
More than 90 percent of popular Southern California freshwater game fish sampled in a new study contained invasive worms capable of infecting humans, scientists are warning. The parasites — two species of flatworms called trematodes — may pose a previously unrecognized public health risk in the United States, according to the study, published on Tuesday in the Journal of Infectious Diseases. In Southern California, these trematodes are 'introduced parasites,' or parasites transported to a new place by an alien host. They often cause gastrointestinal problems, weight loss and lethargy in people — and in more severe cases, strokes or heart attacks, the authors noted. 'Americans don't usually think about parasites when they eat freshwater fish because it hasn't historically been an issue here,' senior author Ryan Hechinger, an ecologist and parasitologist at the University of California San Diego's Scripps Institution of Oceanography, said in a statement. 'But these trematodes have now been widely introduced in the U.S. and that means that doctors and the public should be aware,' Hechinger added. The two trematodes of focus in this study, Haplorchis pumilio and Centrocestus formosanus, likely arrived in the U.S. from Southeast Asia more than a decade ago, according to the study. They presumably did so via the bodies of one of their hosts: an invasive aquatic snail, the red-rimmed melania, which has now spread to 17 states and Puerto Rico. The parasites first move into the snails, which are then consumed by fish — leading them finally to the dinner plate of a warm-blood vertebrate, such as a human or a bird, the authors explained. While previously work led by Hechinger demonstrated the prevalence of red-rimmed melania and the trematode parasites across California, this research aimed to show whether fish that Americans enjoy consuming contains the parasites. To answer this question, Hechinger and his colleagues examined 84 fish across seven species, including largemouth bass and bluegill, from five fishing spots in San Diego County. Ultimately, they discovered that 93 percent of all fish included in the study were infected with the first trematode, Haplorchis pumilio. The second parasite, Centrocestus formosanus, was present at two of the five locations, occurring in 91 percent of those fish, per the study. 'These parasites are here in the U.S., and they're infecting fish that people are eating,' Hechinger said. 'We hope this study can help make public health officials, doctors and the public more aware.' At the same time, Hechinger emphasized that there is 'no need to panic,' as the dangers posed by the parasites can be prevented by fully cooking fish or freezing any fish intended to be consumed raw for at least a week. However, the scientists noted that a social media survey they included in the study showed that Americans may be eating freshwater fish without taking such precautions. Doing so, they warned, can raise the odds of infection considerably. In their survey, which included 125 YouTube videos with a total of nearly 5 million views, the scientists noted that 65 percent made no mention of proper cooking procedures. Going forward, the study authors said they intend to share their results with local public health officials to raise awareness. They expressed hope that their findings would reach medical practitioners, who might not immediately think of trematodes as a possible cause of gastrointestinal infections and other illnesses. The researchers also recommended that fish-borne trematode infection be included on the list of diseases doctors are required to report to public health agencies. 'There haven't been any reported cases of these parasites infecting Americans,' Hechinger said. 'But nobody is looking for cases and doctors aren't required to report them,' he added.
