Latest news with #Haplorchis
Miami Herald
4 days ago
- Health
- Miami Herald
California freshwater fish found to be teeming with parasites. How to keep from getting sick
LOS ANGELES - More than 90% of popular freshwater fish in Southern California are carrying human-infecting parasites, researchers say. This poses a significant danger for those who like to eat freshly caught freshwater fish. But there are ways to protect yourself. The parasites are called trematodes. Two species of the flatworms were discovered in California's freshwater fish, according to a study published Tuesday in the Journal of Infectious Diseases. The tiny, flattened and sluglike creatures can cause gastrointestinal problems, weight loss and lethargy when a person eats an infected fish. In some rare and severe cases, the parasites have caused strokes or heart attacks. "Americans don't usually think about parasites when they eat freshwater fish because it hasn't historically been an issue here," said Ryan Hechinger, the study's senior author. In fact, even when a person has fallen ill from a locally caught infected freshwater fish, their healthcare provider will typically ask if the patient has recently traveled outside of the United States, Hechinger said. California wasn't this parasite's first home Researchers identified two species of trematode: Haplorchis pumilio and Centrocestus formosanus. These two parasite species have historically infected people in Southeast Asia who eat raw fish, crustaceans or vegetables that carry the parasite larvae. A trematode has a very specific life cycle, leeching onto three hosts that include a freshwater snail, a fish and then a bird or human who ate the infected fish. The parasite was probably carried to the U.S. by the red-rimmed melania, or Malaysian trumpet snail, which is host to a number of parasitic species and was introduced to the United States, Hechinger estimates, decades ago. It inhabits "freshwater springs, streams, lakes and swamps," according to the Smithsonian Environmental Research Center, but can occasionally be found in "brackish and marine habitats, especially mangroves" (think the Everglades). The snail first popped up in California in 1972 in a Riverside County ditch, according to the center. Hechinger, through previous and new research, found that the snail and its associated trematode parasites can be widely found in lakes and reservoirs across the state. He's identified the snails in Los Angeles, Imperial, Orange, Riverside, San Bernardino and San Diego counties. Some fish harbor thousands of parasites In summer and fall 2023, researchers, with the help of the California Department of Fish and Wildlife, analyzed fresh fish that were collected at five fishing localities in San Diego County: Miramar, Murray, Lower Otay and San Vicente reservoirs as well as Chollas Lake. The fish included largemouth bass and bluegill. Hechinger and his team found that 93% of all the fish in the study were infected with the H. pumilio parasite, with some individual fish harboring thousands of the parasites. The second parasite, C. formosanus, was found at two of the five locations, where it occurred in 91% of the fish. The parasites are each found on different parts of the fish. H. pumilio is found at the base of the fins and C. formosanus is found on the gills. But the parasites can infect the muscles and connective tissue of the fish, Hechinger said, which is how a person eating it can get sick despite cutting off the head and fins. "The other thing we have to remember," he said, "is the possibility of contamination on the food preparation surfaces and utensils." How to protect yourself The risk is real, but the precautions you can take against illness are straightforward. Thorough cooking of any freshwater fish that could potentially be infected can prevent illness, according to the U.S. Food and Drug Administration. If you choose to eat the fish raw, the agency advises you eat freshwater fish that has been previously frozen. Freezing will kill parasites that may be present. However, the FDA said freezing doesn't kill all harmful germs, so the safest route is to thoroughly cook your seafood. Some food prep is fishy As part of this study, researchers conducted a survey of 125 YouTube videos with a total of 5 million views and found that 65% of these videos did not mention proper cooking or freezing of caught fish. The lack of proper food preparation not only promotes the transmission of parasites but can also increase the odds of infection, Hechinger said. Copyright (C) 2025, Tribune Content Agency, LLC. Portions copyrighted by the respective providers.
Yahoo
5 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.'
Yahoo
5 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
5 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.
