Montgomery Medicine No. 789

Norovirus

You may have read that cases of Norovirus are really ramping up in America. I have been asked to rerun my column on this nasty virus. Most people describe these infections as “stomach flu.” This term, however, can be misleading. Unlike the seasonal flu that affects the respiratory system (also on the increase), the stomach flu, also known as viral gastroenteritis, impacts the digestive system. The seasonal flu shot only prevents respiratory influenza, not viruses that cause gastrointestinal infections.

Norovirus is the leading cause of viral gastroenteritis in the United States, and is responsible for about 21 million cases annually, resulting in roughly 70,000 hospitalizations and around 800 deaths. Norovirus got its name from a 1968 outbreak at a school in Norwalk, Ohio, where it was first identified. The virus is remarkably hardy, able to withstand freezing temperatures, heat up to 140°F, and even resist low levels of chlorine in drinking water. This resilience makes it difficult to eliminate with standard sanitation, and noroviruses can even survive steaming, which is why they sometimes persist in foods like clams and oysters if not properly prepared.

Norovirus infection often comes on suddenly, with symptoms that include nausea, vomiting, diarrhea, and stomach pain or cramps. Diarrhea tends to be especially severe in children, and the resulting dehydration can be dangerous, particularly for the young and elderly. It’s crucial to watch for dehydration signs such as dry mouth, dizziness, and reduced urination in those affected.

Norovirus is highly contagious, especially in crowded places like schools, daycares, nursing homes, cruise ships, family gatherings, and hospitals. When an infected person vomits or has diarrhea, billions of virus particles are released, and swallowing even a small number – as few as 100 particles – can cause infection. The virus is transmitted by direct contact with vomit or stool from an infected person, by touching contaminated surfaces such as doorknobs, toys, or utensils, and by eating contaminated food or drinking contaminated water. Additionally, infected individuals who handle or prepare food can spread the virus to others, leading to outbreaks in places like restaurants, school cafeterias, and at catered events.

Symptoms typically start 24 to 48 hours after infection. Although most people are sick for only one to three days, norovirus can remain in the body for a few weeks after the person feels better. An infected person can be contagious from the moment they start feeling sick until at least three days after symptoms subside, and in some cases, they may remain contagious for up to two weeks after recovery. For this reason, children who have been ill should stay home from school for at least three days after symptoms improve, and anyone who prepares food should avoid working during this period as well.

There is no specific treatment for norovirus, but symptoms can be managed. The primary focus is to prevent dehydration. Drinking water is usually sufficient, but if the illness persists beyond a day, an oral rehydration solution like Pedialyte® may be helpful. A simple homemade solution can be made by mixing two teaspoons of salt and eight teaspoons of sugar into a two-liter bottle of water. Drinking small sips frequently is recommended over gulping large amounts at once. Fever can be managed with medications like acetaminophen or ibuprofen, but it’s always best to consult a healthcare provider, especially when treating children, the elderly, or if symptoms are severe.

Preventing the spread of norovirus mainly involves practicing good hygiene. Regular handwashing with soap and warm water for at least 20 seconds is essential, especially after using the restroom, changing diapers, and before preparing food. Hand sanitizer is not effective. If someone in your home is infected, surfaces should be disinfected with a bleach solution made by mixing one part bleach with nine parts water; allow the solution to sit for 10–20 minutes before wiping. Clothing or linens soiled by vomit or stool should be washed in hot water on the longest cycle and then dried in a dryer. Proper food handling is also important: wash fruits and vegetables thoroughly before eating or cooking, and ensure shellfish is cooked completely. If you are traveling, you should clean surfaces using wipes that contain bleach or hydrogen peroxide.

Most people recover from norovirus on their own. However, it’s essential to seek medical advice if you notice signs of dehydration, such as dry mouth, dizziness, or reduced urination, or if the affected person seems unusually fatigued or has severe abdominal pain. Dehydration can be serious, especially in young children and older adults. While norovirus is unpleasant, understanding how it spreads and taking simple hygiene precautions can help reduce the chances of catching or spreading the virus.