A lot of people made sick by norovirus think they have the flu. The symptoms are similar. But norovirus isn’t the flu at all. It’s a tiny, highly contagious virus that infects the stomach and intestines. It spreads through contaminated food, water, surfaces, and most usually, dirty hands.
The virus is found only in humans, not animals, and it doesn’t need much help to make trouble. A microscopic particle is enough to make you sick. Once ingested, it multiplies rapidly and exits just as quickly, shedding billions of copies that can infect others. It’s so efficient that it’s been called “the perfect pathogen.”
Most outbreaks emerge in familiar places like restaurants, daycare facilities, cruise ships, or long-term care homes. The virus is so hardy that it survives freezing, mild heating, and many cleaning products. Even alcohol-based hand sanitizers, so effective against most bacteria, don’t reliably stop it. Soapy water is the best prevention.
Symptoms of infection include sudden nausea, vomiting, diarrhea, and stomach cramps. It comes on fast but is usually over in two or three days. Most people recover without lasting harm, though the elderly, very young, or those with weakened immune systems can become dangerously dehydrated.
Unlike other viruses, getting it once doesn’t make you stronger. You might think that exposure would at least give your immune system a workout and lead to lasting protection. Unfortunately, norovirus doesn’t play by those rules. Your body does mount a defense and produces antibodies, but they fade quickly – usually within six months to two years – and only protect you from the exact strain that made you sick.