What is the Norovirus?

PATHOGENS & INFECTION PREVENTION INFO
Norovirus
What Is Norovirus?
Norovirus is a highly contagious virus that can cause the sudden onset
of nausea, vomiting and diarrhea. Norovirus infection is often called by
other names such as stomach flu, stomach bug, food poisoning or
viral gastroenteritis.
Norovirus infection is fairly predictable
in that there is not a lot of variation in
symptoms and duration from person
to person. Once exposed, susceptible
persons experience symptoms in
approximately 12–48 hours and severe
symptoms usually last one to two days.
1
While both norovirus infection and
influenza are prevalent in winter,
norovirus does not cause the flu, which
is a severe respiratory infection caused by
influenza viruses.
Norovirus causes illness and outbreaks in many settings. Between 2009
and 2012, almost 3,500 outbreaks were reported to the CDC’s National
Outbreak Reporting System. Of those, 63% were in healthcare settings,
with the overwhelming majority of those outbreaks occurring in long-term
care facilities and nursing homes. Restaurants and banqueting facilities
accounted for 22% of all outbreaks, while 6% occurred in schools.
2
While
noroviruses are the cause for most of the diarrheal outbreaks on cruise
ships, cruise ships account for only 1% of reported norovirus outbreaks.
3
Why Is Norovirus a Concern?
 Norovirus negatively impacts many people. It causes approximately
90% of epidemic nonbacterial outbreaks of gastroenteritis around the
world.
4
In the U.S., norovirus is responsible for 19 million to 21 million
cases of gastroenteritis each year. Almost two million people seek
outpatient treatment, and a further 400,000 seek treatment at
hospital emergency rooms. Annually, 56,000–71,000 people are
hospitalized, and approximately 570–800 die.
5
 While norovirus affects people of all ages, norovirus deaths
disproportionately impact children, the elderly and people with other
illnesses. Dehydration is the main concern with norovirus.
 Norovirus causes many infections and outbreaks each year. A norovirus
outbreak is defined as an occurrence of two or more similar illnesses
resulting from a common exposure to the virus.
How Is Norovirus
Spread?
Norovirus is shed in the stool
(feces) and vomit of infected people.
Transmission results from the
accidental ingestion of very small
amounts of contaminated feces
and vomit. This can occur in
several ways:
Contact with
contaminated surfaces:
Transmission of norovirus via
inanimate objects such as shared
medical equipment, computers and
mobile devices puts the general
public at risk. This is especially true
in locations such as hospitals,
nursing homes, schools and colleges.
Transmission through contaminated
surfaces also increases the risk of
infection for healthcare providers
who care for infected patients, and
for environmental service workers
and custodians who clean and
disinfect contaminated areas.
Contact with contaminated
food and water:
Transmission can also occur in
restaurants and communal eating
areas after an infected worker
has spreads the virus to the food.
Food may also be contaminated
at any point, such as when it's
grown, harvested, processed
or prepared by contaminated
water. Foods that are commonly
responsible for outbreaks include
leafy greens, fresh fruits and
shellfish, particularly oysters.