Food Poisoning or Flu? How to Tell the Difference

The two can trigger similar symptoms, but knowing the difference will help keep you healthy.

May 10, 2017
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It seems like on a weekly or monthly basis we hear about companies issuing voluntary recalls due to potential Salmonella contamination. Oftentimes, no one is sickened by the recalled products, but that's not surprising: Despite all the attention these recalls get in the media, neither E. coli nor Salmonella are the number one cause of food poisoning in this country. That distinction falls to norovirus, a viral infection that is often confused with the flu because it causes similar symptoms. As we move towards a potentially difficult flu season, knowing how to tell an influenza infection from a case of flulike food poisoning will be more important than ever.

THE DETAILS: Norovirus, a.k.a. Norwalk-like virus, is one of the most common causes of foodborne illness in the U.S., responsible for nearly 50 percent of food poisoning cases in the country. It's often mistakenly called the stomach flu, despite the fact that it isn't caused by the influenza virus. The symptoms are very similar to the flu and include nausea, diarrhea, vomiting, and stomach cramps. Some people also complain of fever and chills. The virus is highly contagious and is generally spread by infected food handlers.

More: The 10 Dirtiest Foods You're Eating

WHAT IT MEANS: Because the symptoms of norovirus are so similar to those of the flu, it's easy to confuse the two. And considering that fears over swine flu are ongoing, it's important not to overreact when you start to feel a queasy stomach. Knowing how ID a likely norovirus infection makes it easier to avoid a repeat of the experience, if you can link the episode to what (or where) you ate. Norovirus symptoms usually occur 24 to 48 hours after exposure, but sometimes begin as early as 12 hours after.

Here are a few ways identify norovirus food poisoning, and how to protect yourself:

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Pay attention to the timing

It's easy to confuse norovirus and the flu, says Jason Dees, DO, family physician and board member with the American Academy of Family Physicians. However, unlike norovirus, the standard flu and H1N1 (swine flu) viruses generally cause a cough, runny nose, and sore throat, he says. Also, most cases of norovirus resolve themselves in a day or two. "Anything that lasts longer than that, see a doctor," says Dr. Dees. (However, don't wait if your symptoms are severe, and use these tips to avoid catching the swine flu in public.)

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Look for the letter grade

Norovirus is often spread at restaurants, where an infected chef, waiter, or waitress has passed the disease on to you. A number of cities and county health departments have started requiring restaurants to post their most recent health inspection scores or letter grades somewhere obvious to customers, so look for that when considering a new dining spot. If your local restaurants aren't so regulated, check your health department's website to see if they at least list restaurants that have failed their inspections. If you do get sick, don't rule out a high-graded eatery as the cause. "It's a great baseline to make sure restaurants are meeting standards," says Dr. Dees. "But that means it was safe on the day the inspector was there. Does the 98 on that sheet mean they would score a 98 on the day you eat there?"

More: 50 Foods You May Not Need to Refrigerate

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Touch the chicken

Dr. Dees says that most cases of food poisoning he sees, whether from norovirus or a bacterial infection like salmonella, come from mayonnaise-based foods and undercooked poultry. It might be hard to tell if the mayo's gone bad, but you can at least avoid it when eating at a place you're not familiar with. As for chicken, it should be warm to the touch. "It should be 180 degrees all the way through," he says. "That's pretty hot, so you should feel it." And look for blood—besides being unappetizing, red threads of blood in the meat are signs it is not completely cooked. "White-meat chicken should be white all the way through. Dark meat should have no bloody fluid," says Dr. Dees. If the meat looks undercooked, he adds, send it back, and ask for a replacement on an entirely new dish. "If there was live bacteria in the meat and you cut into it, the juices could be all over that plate and anything else that's on it."

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Stalk the staff

Norovirus is most commonly spread by people who don't wash their hands after using the restroom. If you see a restaurant employee use the restroom without completing that crucial task, bring it to the manager's attention. And do your own part; wash your hands thoroughly before you handle food at home or in restaurants.

More: Don't Make These 5 Classic Hand-Washing Mistakes

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Soak your lettuce

Norovirus has been the source of 60 percent of the foodborne illnesses associated with contaminated leafy greens, making them the most common nonrestaurant source of the disease. Kill germs by soaking your spinach and other greens in a solution of 1 part vinegar and 9 parts water.

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