In News:

Cases of norovirus, commonly known as the "winter vomiting disease," have been rising in the United States in recent weeks, CBS News reported, citing data from the Centers for Disease Control and Prevention.

About Norovirus

• Norovirus is a highly contagious virus that causes acute gastroenteritis, which is inflammation of the stomach and intestines. It is often incorrectly called the “stomach flu,” but it is not related to influenza, which affects the respiratory system. Norovirus outbreaks show a clear seasonal trend, occurring more frequently during colder months.
• Noroviruses are responsible for a major share of viral gastroenteritis cases worldwide, causing the vast majority of outbreaks. People can get infected multiple times in life because there are many different strains and immunity is short-lived.

Transmission

Norovirus spreads very easily and rapidly, especially in crowded and closed environments such as schools, cruise ships, hospitals, hostels, and old-age care facilities.

The virus spreads through:

• Direct contact with an infected person
• Eating contaminated food or drinking contaminated water
• Touching contaminated surfaces and then touching the mouth
• Contact with virus particles present in vomit or faeces

An infected person is contagious from the time symptoms begin and may continue spreading the virus for several days after recovery.

Symptoms

Symptoms usually appear 12 to 48 hours after exposure and are sudden in onset. They include:

• Nausea
• Vomiting (a key feature)
• Diarrhoea
• Stomach cramps
• Low-grade fever
• Headache
• Body aches
• Fatigue

Most cases are mild, but severe fluid loss can lead to dehydration, which is the main complication.

High-Risk Groups

Although people of all ages can be infected, severe disease is more likely in:

• Elderly persons (65 years and above)
• Young children
• Individuals with weakened immune systems

These groups are at higher risk of hospitalisation due to dehydration.

Treatment

There is no specific antiviral drug to cure norovirus infection.

Treatment mainly involves:

• Drinking plenty of fluids or oral rehydration solutions (ORS)
• Rest and supportive care
• Intravenous fluids in severe cases of dehydration

Currently, there is no widely available vaccine for routine prevention.

Prevention

Prevention depends largely on strict hygiene and sanitation.

Key preventive steps include:

• Washing hands thoroughly with soap and water, especially after using the toilet and before eating or preparing food
• Cooking shellfish thoroughly and washing fruits and vegetables properly
• Avoiding raw or undercooked foods
• Cleaning contaminated surfaces with bleach-based disinfectants
• Avoiding close contact with infected individuals
• Staying at home while sick and for at least 48 hours after symptoms stop
• Avoiding preparation of food for others during illness

Alcohol-based sanitizers are less effective against norovirus compared to handwashing with soap and water.

Norovirus vs Influenza

Norovirus affects the digestive system and causes vomiting and diarrhoea, while influenza virus affects the respiratory system and causes cough, sore throat, and body ache. The term “stomach flu” for norovirus is therefore medically incorrect.