What is norovirus and how contagious is it?

"Norovirus is the term for a family of about 50 strains of virus that all share one miserable endpoint: copious time in the bathroom. Every year, an estimated 684 million people globally come down with it. Norovirus is a kind of infectious gastroenteritis, an inflammation of the bowel and the colon that can cause diarrhea and vomiting, explains Dr Ambreen Allana, an infectious disease physician based in Texas."

"The virus typically enters the gastrointestinal tract via tiny viral particles from an infected person's saliva or feces. These particles may end up on your hands, or in food or drink, and ultimately in your mouth what we call the fecal-oral route, Washer says. Particles remain infectious for up to two weeks on hard surfaces like doorknobs and bathroom fixtures, and it takes very little exposure to make you sick. The infectious dose of noroviruses is less than 20 virus particles, says Washer."

"There is also some risk of transmission via aerosolized particles, particularly if you're around someone while they are experiencing symptoms like diarrhea or vomiting. Norovirus becomes contagious about two days prior to the onset of symptoms, and people can remain contagious for days or even weeks after they're feeling better. Close quarters such as eldercare facilities, daycares and airports are a perfect nidus for catching infection, says Allana."

Norovirus comprises about 50 viral strains that cause infectious gastroenteritis, producing diarrhea and vomiting. Approximately 684 million people are infected globally each year. Transmission occurs primarily via the fecal-oral route when tiny viral particles from saliva or feces contaminate hands, food, drink, or surfaces. Viral particles can remain infectious up to two weeks on hard surfaces, and the infectious dose is very low—fewer than 20 particles. Aerosolized particles from vomiting or diarrhea can also transmit infection. Norovirus becomes contagious about two days before symptoms and can remain contagious for days to weeks after recovery. Close, crowded settings foster outbreaks, especially during Northern Hemisphere winter months.

Read at www.theguardian.com