norovirus

Norovirus is a highly contagious virus that causes gastroenteritis, an infection of the stomach and intestines that leads to symptoms such as vomiting, diarrhea, nausea, and stomach cramps. It spreads easily through contact with infected individuals, contaminated food or water, or contaminated surfaces, and is a common cause of outbreaks in places where people gather closely together, such as cruise ships, schools, hospitals, and nursing homes. Although illness is usually short-lived, norovirus spreads rapidly and is one of the leading causes of foodborne illness worldwide.

Norovirus spreads very easily through direct contact with infected individuals, consumption of contaminated food or water, or contact with contaminated surfaces. The virus can be transferred when people touch objects such as door handles, railings, or shared utensils and then touch their mouth. It also spreads rapidly in crowded or enclosed environments—including cruise ships, schools, hospitals, and nursing homes—because only a small number of viral particles are needed to cause infection.

Norovirus outbreaks on cruise ships are relatively uncommon compared with the enormous number of voyages and passengers each year, but they receive outsized attention because they can spread rapidly and can significantly disrupt vacations. According to the U.S. Centers for Disease Control and Prevention (CDC), norovirus outbreaks among cruise passengers account for only about 1 percent of all reported cases, on land or at sea, and affect about 3 to 5 percent of individuals on a given voyage. Norovirus is still the most frequently identified cause of gastrointestinal outbreaks at sea because it is extremely contagious and spreads easily.

Norovirus infection can be prevented through careful hygiene and food safety practices. Frequent handwashing with soap and water is especially important, since alcohol-based sanitizers may be less effective against the virus. Additional preventive measures include thoroughly washing fruits and vegetables, properly cooking shellfish, disinfecting contaminated surfaces, and avoiding close contact with infected individuals. Because people can continue spreading the virus after symptoms improve, staying home and limiting contact with others for several days after illness can also help reduce transmission.