In recent years, Americans have been eating and buying more seafood. Shrimp are among the most popular seafood consumed by Americans. The average American eats about 4.6 pounds each year.
But is shrimp safe to eat raw? Here’s what you need to know.
Types of Shrimp
The term "shrimp" includes many different species of similar-looking shellfish. Cold-water shrimp are small and harvested in the oceans in the northwest and northeast regions of the U.S. and Canada.
Warm-water shrimp are harvested in tropical areas and are usually farmed. More than 90% of the shrimp consumed in the US are from farmed sources. Most of the seafood eaten in the U.S. is imported from other countries, such as China, India, Thailand, and Vietnam.
Shrimp and Foodborne Illnesses
The Food and Drug Administration (FDA) says pregnant women and young children should avoid raw seafood. Their weaker immune systems put them more at risk for foodborne illnesses.
Raw shrimp can harbor several types of harmful bacteria that can cause illness in humans.
Vibriosis. Vibrio (or Vibrio vulnificus) is a marine bacterium found in sea creatures. It makes humans sick with an illness called vibriosis. You can get infected with this germ by eating raw or uncooked seafood. But you can also be infected if a wound comes into contact with raw or undercooked seafood or its juices.
If you come down with a mild case of vibriosis, you will likely get better after about three days. But 20% of people with Vibrio infections die, sometimes within a few days of getting sick.
Symptoms of this infection include:
- Watery diarrhea, often along with stomach cramps, vomiting, nausea, and fever,
- Fever, chills, low blood pressure, and blistering skin lesions, signs of bloodstream infection.
- Fever, redness, swelling, discharge, discoloration, and pain. These are symptoms of wound infection and may spread to the rest of the body.
Researchers tested shrimp bought from a fish market and found that seven out of 20, 35%, of the shrimp had Vibrio bacteria. And 100 strains of Vibrio — many resistant to antibiotics — have been found in farmed shrimp.
Cholera. Cholera is an infection of the intestines that causes diarrhea. You can get cholera by drinking water or eating food that’s contaminated with cholera bacteria. It’s also occasionally spread when raw or undercooked shellfish are eaten.
The Vibrio cholerae bacteria that cause cholera attach themselves to the shells of shrimp, crabs, and other shellfish. Cholera is rare in the U.S., but it’s a major infection in many parts of the world.
In a study of a major shrimp-producing area in Thailand, researchers found Vibrio cholerae non-O1 in 33% of the samples tested. This germ has been associated with cases of gastroenteritis or “stomach flu”.
Parasites. Shrimp, like all living creatures, can have parasites. These germs that depend on a host for nourishment may lurk in seafood that is eaten raw or is lightly preserved, such as sashimi, sushi, and ceviche. This is why restaurants use commercially frozen seafood to prepare sashimi and sushi.
Here are FDA guidelines for how cold seafood that’s sold for raw consumption should be and for how long it should be stored:
- -4F (-20C) or below for seven days.
- -31F (-35C) or below until solid, and stored at -31F (-35C) for 15 hours.
- -31F (-35C) or below until solid, and stored at -4F (-20C) for 24 hours.
If you do eat raw shrimp, be sure to purchase it from restaurants and markets with a good reputation for cleanliness and safety. For the most part, though, organizations concerned with food safety recommend that you cook your seafood. Most seafood should be cooked to an internal temperature of 145F (63C).
Raw seafood that has spoiled can have odors that are sour, rancid, or ammonia-like. Cooking makes these smells stronger. Don’t eat raw or cooked seafood that has these odors.
How to Choose and Prepare Shrimp
Unless you live near the sea, the shrimp at your local supermarkets aren’t likely to be fresh. You can buy them frozen or thawed, that is, “previously frozen.”
When you see a product labeled “fresh frozen,” it means that the seafood was frozen when it was fresh, often within a few hours of harvest. Frozen seafood can be better in quality compared to fresh seafood. But don’t buy frozen shrimp if the package shows signs of ice crystals or frost.
If buying fresh shrimp, check that it’s refrigerated or placed on a bed of fresh ice. Most varieties of shrimp have shells that are translucent with a light pinkish or a grayish green tint. Check that the shells don’t have black spots or blackened edges. Tiger shrimp have black lines between the shell segments; that's OK.
If you will use the shrimp within two days, store it in your fridge. Otherwise, put it in the coldest part of your freezer. It can be frozen for up to five months.
When preparing your raw shrimp, start by washing it. Don’t let its juices come into contact with other foods. After preparing raw seafood, wash your cutting board, counter, utensils, sink, and hands well with hot, soapy water. Serve your cooked seafood on clean plates, not the plates that held the raw seafood.
When you cook your shrimp thoroughly, you'll see it turn opaque white with a little pink.