Can I get sick from eating raw seafood?

Dear Alice,

I love sushi, sashimi, and oysters on the half shell. I apparently am uneducated (ignorant) when it comes to the health risks associated with eating raw seafood. I read in an article that a person could contract hepatitis A and worms. Is hepatitis A something that is "curable"? Are ANY of the diseases/problems associated with eating raw fish NOT "curable?"

Dear Reader,  

Raw fish and seafood can be both tasty delectables and components of a balanced pattern of eating. Many consumers may also appreciate learning more about the health risks of raw fish, which are generally minimal in comparison to other means of transmitting foodborne illness. Fish are touted as a low-fat source of protein packed with vitamins and minerals, such as omega-3 fatty acids, calcium, vitamin D, and many others. Better yet, these nutrients may help reduce the risk of heart disease, lower blood pressure, and improve brain function. For some populations, such as native or indigenous communities, consuming fish is central to their culture, traditions, or heritage. While there are numerous health and social benefits, the chances of illness depend somewhat on other health conditions of the consumer and how the raw seafood is handled and prepared (more on this in a bit). Though most food-related diseases are indeed incurable, many of them go away on their own and can be prevented with proper handling, preparation, and storage.   

As you mention, the hepatitis A virus can be found in some raw shellfish, but it isn’t common in other seafood. Hepatitis A, unlike other types such as hepatitis B and hepatitis C, doesn’t cause long-term or chronic illness. Hepatitis A is killed by heat, so it’s not a concern for those enjoying cooked shellfish dishes. It’s incubation period (the time it takes from eating the food until beginning to exhibit symptoms) ranges from 15 to 50 days. This virus causes inflammation of the liver and interferes with liver function. Symptoms of hepatitis A can include:  

  • Fever  
  • Tiredness  
  • Loss of appetite  
  • Abdominal discomfort  
  • Dark urine  
  • Jaundice (yellow skin)  
  • Nausea  
  • No symptoms at all  

Those who become infected can be sick for up to six months, but the liver usually heals on its own within a month or two. Mild cases require no treatment and once the infected individual heals, they’ll have immunity for life. A health care provider can do a blood test to see if you've already been exposed to hepatitis A. The good news is that there’s also a vaccine, which is now given routinely to children as part of their vaccination program or when traveling to certain countries. 

Worms (and worm eggs) can be a concern when consuming raw fish, though they’re preventable and treatable. Worms are killed when the fish is cooked or completely frozen but can be passed on in the raw state. This includes not just sashimi or sushi, but also some other popular dishes, such as partially raw seared fish fillets and ceviche — raw fish marinated in lime or other citrus juice. Most worms will pass through the digestive system without causing any problems, but two can cause infections: roundworm larvae and a type of tapeworm species diphyllobothrium. Infection by either of these two parasites can result in abdominal discomfort, diarrhea, fatigue, and feelings of weakness in the arms and legs. Your health care provider may prescribe oral medication that’s toxic to the worms.  

While the risks for seafood are limited for some, others such as young children, older adults, and pregnant people are at a higher risk of health complications. For pregnant people, it’s recommended that they avoid raw seafood since it can pose a risk of miscarriage and early delivery. For more information, you can check out the Food Administration (FDA) food safety guidelines for pregnant people. It’s also recommended that folks with certain conditions consult with a health care provider before eating raw fish or shellfish, if they have:  

  • Liver disease  
  • Human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS)  
  • Diabetes  
  • Stomach disorders  
  • Inflammatory bowel disease  
  • Cancer  
  • Abnormal iron metabolism  
  • Other autoimmune disorders  

In the context of foodborne illnesses, the risks posed by raw seafood are generally lower than raw animal meat such as beef and pork. Uncooked animal meat tends to have more bacteria, which can spread widely due to the nature of slaughtering and mixed packaging. Unlike raw animal meat, fish are typically frozen right after being caught in cold waters, which can kill lingering bacteria (though the effectiveness varies based on freezing time, temperature, and type of parasite). And while the risk is low, it can be further reduced by informed purchasing from credible stores. For tips, you can visit the Food and Drug Administration’s safe seafood shopping. When eating out, it’s recommended to choose reputable restaurants that know how to salt and season raw fish, which can help kill bacteria. Also, trained sushi chefs have learned how to identify worms or worm eggs in fish, and trusted packing houses use a process called candling (quite simple: holding the fish to light) to check for worms in the fillets. If you’re still concerned, you might consider sticking with cooked seafood (heated to at least 145 degrees Fahrenheit) or trying canned or refrigerated smoked seafood.  

While expanding international trade has been linked to a rise in seafood infections, it doesn’t mean you have to give up your sushi, sashimi, and oysters. While raw fish and seafood sometimes get a bad rap, it’s helpful to know that there are toxins found even in cooked foods. With wise dining, preparing, and shopping decisions, the risks posed by eating raw or undercooked seafood are relatively low for those not in high-risk groups. Hopefully this information will help you in weighing the risks of feasting on the bounties of the sea.  

Bon appétit!  

Last updated Jul 16, 2021
Originally published Feb 20, 2004

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