Norovirus, also known as stomach flu, is a group of viruses that cause inflammation in the stomach and intestines. There are an estimated 2,500 reported norovirus outbreaks in the United States each year, according to the Centers for Disease Control and Prevention (CDC). While norovirus is common in the winter and spreads easily, there are actions you can take to keep yourself and others safe.

Bernard Camins, MD

In this Q&A, Bernard Camins, MD, Professor of Medicine (Infectious Diseases) at the Icahn School of Medicine at Mount Sinai and the Medical Director for Infection Prevention for the Mount Sinai Health System, explains how to prevent and treat norovirus.

What are the symptoms of norovirus?
The most common symptoms are nausea, vomiting, and diarrhea. Some people may have fevers and chills.

How long does norovirus infection last?
About one to three days.

How contagious is norovirus, and for how long?
Norovirus is very contagious. Most people are contagious for at least three days, and some people are contagious for up to two weeks, even after symptoms are gone.

How does norovirus spread?
Norovirus is primarily spread through fecal-oral transmission—for example, restaurant staff or members of the same household fail to thoroughly wash their hands after using the bathroom, then spread it to others through contaminated food. You can also get it by touching shared surfaces from a sick person after they use the bathroom and less commonly from droplets contaminated with the virus when an infected person vomits.

How can I prevent norovirus?
Number one is to wash your hands thoroughly with soap for 20 seconds before eating or preparing meals. Alcohol-based sanitizers do not work as effectively against norovirus. Stay home if you are sick and avoid preparing food for others or sharing food, and avoid shared bathrooms, if possible. If you do have to share a bathroom, disinfect the toilet, sink, door handles, and any other shared surfaces, after you use it. Do not share dishes, utensils, or cups.

How can I treat norovirus?
The most important thing is to prevent dehydration by drinking water, juice, or a sports drink. Eat bland foods if you can tolerate them.

How do I know if I should see a doctor?
While norovirus symptoms are often severe, most infections clear on their own after a few days and do not require a doctor. However, if you are not able to keep liquids down, you should seek medical attention.

What should I do if my child has norovirus?
Keep them home. Norovirus can lead to severe dehydration in babies and children with underlying health problems. Learn more about what to do if you suspect your child has norovirus.

Is norovirus worse this year than previous years, and if so, why?
There is no evidence that norovirus is worse this year compared to previous years. Norovirus outbreaks usually happen around January due to people gathering for the holidays. Peak season for norovirus is November through April.

If you live in the New York City region, you probably heard news reports of a “flesh-eating bacteria” that has sickened several people. The disease is caused by an infection from a bacteria called Vibrio vulnificus, which can cause severe wound infections and, sometimes, blood stream infections, sepsis, and even death.

While worrisome, Vibrio vulnificus is extremely rare. Every year, there are about 100 cases reported in the United States. Vibrio vulnificus is less concerning for the general population, but is a major risk if you have a weakened immune system.

Timothy Sullivan, MD

In this Q&A, Timothy Sullivan, MD,  an infectious diseases physician and Associate Professor of Medicine (Infectious Diseases) at the Icahn School of Medicine at Mount Sinai, discusses why people are getting infected with Vibrio vulnificus in New York City, how to prevent it, and what to do if you’ve been infected.

Why are people suddenly getting infected with Vibrio vulnificus in the New York City region?

Vibrio vulnificus tends to grow in brackish water, which is a mixture of saltwater and freshwater that occurs in estuary areas where rivers meet ocean water, such as the Long Island Sound. As the bacteria tend to grow more rapidly in warm water, the disease has always been more common during the summertime. However, there seems to be a link between climate change and these infections. In recent years, it seems these infections have become increasingly common in more northern climates as ocean water temperatures rise globally.

What are the risks?

Those most at risk are people with weakened immune systems, which can be caused by a number of issues, including having an underlying liver disease, if you are a transplant recipient, or if you are undergoing cancer treatment. Among these individuals, you are at risk if you have open wounds, recent tattoos or piercings, and have been exposed to brackish water, or if you eat raw or undercooked shellfish.

What are the symptoms?

The symptoms depend on whether you were exposed to Vibrio vulnificus through brackish water or by eating raw or undercooked shellfish. If you were exposed through water, you can develop a wound infection, which would include redness, pain, and swelling near the wound. With this disease in particular, wound infections can progress very rapidly and progress to a condition called necrotizing fasciitis that destroys tissue beneath the skin, which is why the disease is referred to as “flesh-eating bacteria.” That infection can develop into severe redness and pain that spreads rapidly from the area of initial infection. The first signs and symptoms of infection following eating raw or undercooked shellfish include nausea, vomiting, diarrhea, and abdominal pain. If a severe infection develops, you may experience fevers, chills, rapid heart rate, low blood pressure, and confusion, which are all signs of a very severe bloodstream infection.

How is the disease treated?

A Vibrio vulnificus infection is typically treated with intravenous antibiotics. If you develop a severe wound infection, you may need to undergo surgery. In the most severe cases that develop into necrotizing infections, amputation may be required.

What should I do to avoid infection?

These recommendations are not for the general population but primarily for people who have weakened immune systems. Do not eat raw or undercooked shellfish, not only to avoid infection from Vibrio vulnificus but other potentially harmful bacteria, as well. You should also avoid direct exposure to brackish water or estuary regions. Even if you don’t have open wounds, avoid brackish water and handling shellfish, since you could injure yourself, such as being in a boating accident or cutting yourself while shucking oysters. If you are at risk for severe infection and have a wound that has been exposed to brackish water, raw seafood, or seafood juices, wash the wound as soon as possible with soap and water. If you want to eat shellfish, make sure it is well cooked.

What should I do if I think I’m infected?

A Vibrio vulnificus infection may be a medical emergency, so if you have a possible exposure to Vibrio vulnificus and signs of infection, you should go to the hospital immediately. You would need to be started on appropriate antibiotics and, if necessary, undergo surgery. Communicate to your doctor your risk factors and exactly how you were exposed, so they can accurately diagnose you and start your appropriate treatment as soon as possible.