Do you think your freshwater fish is safe? 93% of parasites can infect humans

More than 90% of invasive parasites in Southern California ports are able to infect humans, according to new research by the Scripps Institute of Oceanography at the University of California, San Diego. The study, published in the Journal of Infectious Diseases, reveals that fish that Americans often catch and consume carry large quantities of parasite worms that can cause gastrointestinal problems, weight loss, and in severe cases, stroke or heart attack.

More than a decade ago, invasive snails from Southeast Asia were in the United States, and the parasite was called trematides. Now, they have spread to fishing, millions of Americans catch and eat, creating what researchers say is previously unacceptable public health risks.

Hidden threats in capture

“Americans usually don’t consider parasites when eating freshwater fish because it’s not historically a problem,” said Ryan Hechinger, an ecologist and parasitologist at Scripps. “But these Trematodes are now widely introduced in the United States, which means doctors and the public should be aware of it.”

The researchers examined 84 species of fish from seven different species, including Largemouth Bass and Blue G, collected in 2023 from five popular fishing locations in San Diego County. Their findings are distinct: 93% of all fish contain a single pumilio parasite, some of which belong to individual fish carrying thousands of microscope invaders.

The second parasite, Consaria, had 91% of the fish infected in the five locations present. Both parasites initially infected people in Southeast Asia and then snails that are convenient for the red melania, and have now spread to 17 states and Puerto Rico.

How fish become mobile parasite hotels

Trematodes follows a complex three-master life cycle, converting fish into uninformed carriers. Freely released parasite larvae exit the infected snail and dig into fish tissues to form a protective cyst called Metacercariae. These infectious stages focus on different parts of the fish, depending on the species – Haplorchis Pumilio is embedded primarily in the fin base and surrounding muscle tissue, while central forazacia prefers g.

What makes this particularly worrying is the parasite load. One blue g collected during the study period contains 16,973 haplozoar pumilio and 8 Centrocestus formosanus larvae. Even fish that look completely healthy can hide hundreds or thousands of parasites without showing any obvious signs of infection.

YouTube video reveals risky eating habits

The researchers did not stop examining the fish. They analyzed 125 YouTube videos and had nearly 5 million comprehensive views to see how Americans actually prepare and eat freshwater fish. The results are disturbing: 65% of the videos show that people consume primitive, unspreaded fish, which is a condition that allows parasites to survive and infect humans.

“There is nearly 5 million views that are common interest may be the widespread custom of eating freshwater fish,” said Emma Palmer, a marine scientist at the Smithsonian Center for Environmental Research.

Many videos promote dangerous misunderstandings about food safety. Popular myths include claiming that citrus marinade “cook” the fish and kills parasites, that healthy fish can be eaten safely, or that visual inspections can detect parasites. None of these beliefs are scientifically accurate.

Key research results:

• 93% of freshwater game fish carry human-infected parasites
• Some fish hide over 16,000 individual parasite larvae
• 65% of YouTube fishing videos show unsafe raw fish consumption
• Videos collectively attracted nearly 5 million viewers, demonstrating a wide range of risk practices
• Parasites now present in fish in multiple states where invasive snails exist

Simple prevention, serious consequences

Hechinger emphasizes that “no panic is needed” because prevention is simple. Follow the Food and Drug Administration’s guidelines, boiling fish thoroughly or freezing any original consumption for at least one week will kill the parasite. In most cases, these parasites cause relatively mild symptoms, but months or years of chronic infection can pose greater health risks.

However, the gap between security practice and reality involves researchers. Research shows that many people rely on freshwater fish as food, especially in communities that may lack proper education for proper preparation.

“These parasites are in the United States and they are infecting the fish people are eating,” Hechinger said. “We hope this study can help make public health officials, doctors and the public more aware.”

A growing but hidden problem

Perhaps the most worrying thing is the invisibility of this health threat. “There are no reports of these parasites infecting Americans, but no one is looking for cases and doctors don’t need to report them,” Hechinger said.

Researchers believe many infections are not diagnosed because American doctors rarely consider these tropical parasites when treating gastrointestinal complaints. To address this blind spot, they recommend adding fish-borne giant infections to the list of diseases doctors must report to public health officials.

The team plans to share their findings with the Southern California County Health Department and hope to contact doctors who may experience these infections without acknowledging them. As invasive snails continue to spread to the United States, the geographical scope of this health risk may expand.

“This kind of research is very important to identify new public health threats, and it is impossible without NIH funding,” Hechinger said. “This is a research that a private company will never fund because it will not make anyone rich, but it may make the public healthier. If the federal government does not fund such research, who will it be?”

As Americans increasingly embrace various culinary traditions, including raw fish dishes, it becomes increasingly important to understand and prevent these hidden health risks. The solution is still simple: cook the capture thoroughly, or freeze it first if you prefer to be raw.

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