Eating raw or undercooked seafood — such as sushi or oysters — may seem like a delicious meal. However, eating these foods may also expose you to health risks. Eating raw or undercooked shellfish can have several adverse effects on the body. These effects can range anywhere from mild discomfort to death.
Eating raw or undercooked fish can place you at risk of becoming a host to a parasite such as tape worm. Some varieties of fish are more prone to parasites than others. These include trout, cod and some types of wild salmon. Health effects of developing tape worms can include pain, anemia and low energy. Additionally, some parasites require surgical removal. Markets and restaurants do typically take steps to reduce the chances of preparing or selling parasite infested fish. Fish that are meant to be eaten raw are typically frozen for a week to kill any parasites. Additionally, many stores examine fish before selling it to make sure it is free of parasites. However, thoroughly cooking the fish before eating it is the best way to ensure it is free of parasites.
Eating raw or undercooked fish can place you at risk of contracting bacteria. Raw or undercooked shellfish can increase the risk of exposure to Vibrio bacteria. There are approximately 95 cases of Vibrio infection each year and approximately 50 percent are the result of eating raw or undercooked seafood. Exposure to this bacteria can result in nausea, stomach pain, vomiting and diarrhea. Those with weak immune systems are particularly susceptible to illness from these bacteria and may experience life threatening illnesses. According to the University of Georgia 40 percent of Vibrio cases prove to be fatal — the death rate is 50 percent when the Vibrio infection comes from food.
Eating raw and undercooked seafood can also expose you to viruses. Norovirus is a stomach bug that is the leading cause of foodborne disease outbreaks in the United States according to the Centers for Disease Control and Prevention. The virus is highly contagious; it can be spread from person to person as well as contact with contaminated foods including raw oysters and shellfish. Exposure to the virus causes diarrhea, nausea, vomiting, stomach pains, fever and headache. Symptoms typically appear within 24 to 48 hours of ingesting the seafood but can appear as soon as 12 hours after exposure to the virus.
Avoiding Health Risks
Cooking your seafood to proper temperature is the simplest way to prevent any negative consequences. Cook your seafood until the internal temperature reaches 145 degrees Fahrenheit. It is possible to ensure your seafood is thoroughly cooked even if you do not have access to a thermometer. Cook fish until the flesh is slightly translucent. Cook shrimp until they turn pink and lobsters until they become red and the flesh appears pearly and opaque. Cook scallops until they become milky white or opaque and firm to the touch. Clams, mussels and oysters that open while cooking are ready to eat. Discard any that do not open.
References and Resources"ABC News"; Eat Raw Fish Get a 9-Foot Tapeworm; Lauren Cox; June 2009
"NC State University"; Is Our Seafood Safe to Eat; Lorraine DiBella;
FDA: Medical Professionals - Foodborne Pathogens
CDC: Norovirus Key Facts