Russo Offers Safety Tips for Eating Seafood, Including Raw

By Ellen Goldbaum

While the great majority of commercial seafood products in the U.S. are safe to consume, a University at Buffalo infectious disease expert says it’s important to know about some exceptions and precautions.

Thomas A. Russo, MD, is a SUNY Distinguished Professor in the Division of Infectious Diseases in the Department of Medicine in the Jacobs School of Medicine and Biomedical Sciences at UB. He recently gave a grand rounds lecture to Jacobs School faculty and trainees on the potential health risks of eating seafood.

Russo says that the great majority of fish purchased and served commercially in the U.S. is safe to eat, including raw fish. “Freezing is mandated by the USDA for fish intended to be eaten raw or undercooked, making the risk in the U.S. negligible,” says Russo.

His top seafood safety tips are:

• prevention is key
• avoid large predatory reef fish that are larger than five pounds, especially high-risk species like barracuda
• to avoid shellfish poisoning, avoid consuming mollusks when harmful algal blooms and “red tides” are occurring
• cook fish to an internal temperature of 63 degrees Celsius (145 degrees Fahrenheit); it should be opaque and flake easily; it should not look gelatinous
• boiling clams/mussels is more effective than steaming; continue boiling for at least 2 minutes after all valves open or internal temperatures reach at least 90 degrees Celsius (194 degrees Fahrenheit) for at least 90 seconds
• especially if you plan to travel, hepatitis A or typhoid vaccination may be appropriate
• do not participate in food dares/challenges, especially involving eating raw or undercooked noncommercial fish or shellfish

While a broad range of toxins, allergens, infectious agents and chemicals can contaminate seafood, Russo stresses that many of these are rare and their incidence is, in general, very low in the U.S. However, certain populations should limit or avoid consumption of certain seafoods.

For example, he says, nearly 98% of fish sold in the U.S. meet safety standards regarding methyl mercury contamination — its concentration is highest in predatory fish, such as swordfish, tuna, shark and bluefish. Still, he says, consumption of these fish should be limited to no more than four meals a month for adults and two meals a month for children; pregnant women should avoid eating these fish altogether.

“Raw oysters and undercooked mussels and clams carry the greatest risk for infectious agents,” says Russo. In the U.S. the most common infections that can be acquired from these mollusks are hepatitis A or norovirus, which can only be treated with supportive care.

Infections can also result from improper food processing and handling. While these typically resolve on their own in healthy people, some such as listeria can be lethal in immunocompromised people and can result in abortion, stillbirth, or sepsis in pregnant women, and neonatal sepsis.

“In addition, immunocompromised patients or patients with cirrhosis of the liver should avoid raw oysters as naturally occurring infectious agents may be present (e.g. Vibrio vulnificus), which can cause severe infection in this patient population with a mortality rate of up to 40-50%,” warns Russo.

For people traveling outside the U.S., he stresses “buyer beware” noting that consuming raw seafood carries an increased risk in countries that do not have stringent public health measures that minimize or eliminate the risk of infection.

As for the seafood products Russo enjoys, he says: “I eat sushi and sashimi and gently seared tuna steaks. For seafood not meant for raw or undercooked consumption, I ensure that it is properly cooked. I do not eat raw oysters.”