Norovirus is a contagious stomach bug that infects 685 million
people around the world each year. Cruise ships, nursing homes, and daycare centers are common breeding
grounds for norovirus.
Despite its prevalence,
norovirus - which has no specific treatment and is particularly dangerous
in infants and the elderly - has received surprisingly little attention
from researchers. In a review article published in Trends in Molecular Medicine
Washington University School of Medicine scientists and colleagues at
the University of Michigan Medical School discuss what we know about the
‘Norovirus is a contagious stomach bug which has no specific treatment and is particularly dangerous in infants and the elderly.’
1. People can shed norovirus for months.
Norovirus has a high tolerance for disinfectants and with an average
1.2-day incubation period, it can spread quickly. Although symptoms
such as abdominal pain, nausea, vomiting, and diarrhea typically resolve
within one to four days, it is also possible for a person to shed the virus
before symptoms appear and after their resolution. Viral shedding can
occur for up to a few months in healthy individuals and for years in
immunocompromised patients. The severity of symptoms does not correlate
with Norovirus shedding, which makes protection against the virus rather
2. In a norovirus hot zone? Wash your hands.
Norovirus thrives in crowded public areas. Outbreaks spread when
people eat or drink contaminated food, touch infected surfaces, or come
into contact with someone shedding the virus. "Norovirus is extremely
contagious and so washing your hands frequently is important," says
review co-author Megan Baldridge, a physician studying pathogens and the
microbiome at the Washington University School of Medicine in St.
Louis. "If you start to feel symptoms, avoid preparing food for other
people and be careful to clean any surfaces that might be contaminated
3. Some people are more susceptible to norovirus than others.
There are many different types of norovirus and people can be
infected multiple times during their lifetimes. The infection is
different for each species that is infected by the virus and how humans
react to the virus is dependent on their genes. "Healthier people may
get the virus and have uncomfortable, unpleasant symptoms for a few
days, but those symptoms will resolve quickly," Baldridge says. "What
can happen with people who are immunocompromised is that they can have a
chronic debilitating infection that can be highly detrimental."
4. Norovirus can trigger other gut problems.
Norovirus has been suggested as a possible trigger for other gut
diseases, including irritable bowel syndrome (IBS) and inflammatory
bowel disease (IBD). Under certain conditions, norovirus infection may
also alter normal resident intestinal bacteria and allow other
infections to occur. Although there is much research to be done
regarding the causes of different gut diseases, we know that various
pathogens can affect how the virus reacts and these reactions may
trigger other intestinal problems. "We're just starting to understand
how there's a very complex interplay between norovirus infection and all
the other different pathogens and commensal bacteria that could be
present," Baldridge says. "These factors likely have very complex
interactions with the gut."
5. There is no vaccine, but new strategies are on the horizon.
Vaccine and treatment research has been limited because of a lack of
understanding of norovirus within humans, but recent discoveries in
mice have identified that certain biological factors can slow down or
kill the virus. "Up until now vaccines have exclusively been using
virus-like particles, but some new developments may make it possible to
generate a live attenuated vaccine, which is pretty exciting," Baldridge says. "Having animal models and cell culture models to grow
the virus and study how it acts a little more closely will help us
better understand the virus and also think more about vaccination