Parasites in Southern California Freshwater Game Fish: Risks and Precautions

Parasites in Southern California Freshwater Game Fish: Risks and Precautions

Freshwater game fish in Southern California are found to contain parasites that can potentially cause strokes or heart attacks in humans who consume them. Researchers have identified two species of flatworms, known as trematodes, in over 90 percent of popular freshwater game fish. These parasites, which are only a few centimeters long, can lead to symptoms like weight loss or lethargy and, in rare cases, more severe consequences.

The study, published in the Journal of Infectious Diseases and funded by the National Institutes of Health, was conducted by researchers from UC San Diego's Scripps Institution of Oceanography and the University of Nebraska. They examined 84 fish from seven different species collected from fishing locations in San Diego County. The majority of the fish were infected with the Haplorchis pumilio parasite, with some fish hosting thousands of parasites. Another parasite, Centrocestus formosanus, was found in fish from two locations.

The trematodes, historically prevalent in Southeast Asia, likely arrived in the U.S. over a decade ago through an invasive aquatic snail called the red-rimmed melania. This snail is now found in 17 states and Puerto Rico. While there have been no reported cases of parasite infections in Americans yet, researchers emphasize the importance of monitoring fish advisories and taking precautions when consuming freshwater fish.

To mitigate the risks posed by these parasites, it is recommended to thoroughly cook fish or freeze it for at least a week before consumption to ensure the parasites are killed. Despite these precautions, many Americans may be consuming freshwater fish without taking these steps, potentially leading to repeated infections over time. The authors stress the need for fish-borne trematode infections to be added to the list of diseases that doctors are required to report to public health officials.

The presence of these parasites in freshwater fish highlights the importance of raising awareness among public health officials, doctors, and the general public. By being informed about the risks associated with consuming infected fish and taking appropriate precautions, individuals can minimize the potential health threats posed by these parasites.