|What are noroviruses?
Noroviruses are a group of viruses that cause the “stomach flu,” or
gastroenteritis (GAS-tro-en-ter-I-tis), in people. The term norovirus was
recently approved as the official name for this group of viruses. Several
other names have been used for noroviruses, including:
- Norwalk-like viruses (NLVs)
- caliciviruses (because they belong to the virus
- small round structured viruses.
Viruses are very different from bacteria and
parasites, some of which can cause illnesses similar to norvirus
infection. Viruses are much smaller, are not affected by treatment with
antibiotics, and cannot grow outside of a person’s body.
What are the symptoms of illness caused by noroviruses?
The symptoms of norovirus illness usually include nausea, vomiting,
diarrhea, and some stomach cramping. Sometimes people additionally have a
low-grade fever, chills, headache, muscle aches, and a general sense of
tiredness. The illness often begins suddenly, and the infected person may
feel very sick. The illness is usually brief, with symptoms lasting only
about 1 or 2 days. In general, children experience more vomiting than
adults. Most people with norovirus illness have both of these symptoms.
What is the name of the illness caused by noroviruses?
Illness caused by norovirus infection has several names, including:
- stomach flu – this “stomach flu” is not related
to the flu (or influenza), which is a respiratory illness caused by
- viral gastroenteritis – the most common name for
illness caused by norovirus. Gastroenteritis refers to an inflammation
of the stomach and intestines.
- acute gastroenteritis
- non-bacterial gastroenteritis
- food poisoning (although there are other causes
of food poisoning)
- calicivirus infection
How serious is norovirus disease?
Norovirus disease is usually not serious, although people may feel very
sick and vomit many times a day. Most people get better within 1 or 2
days, and they have no long-term health effects related to their illness.
However, sometimes people are unable to drink enough liquids to replace
the liquids they lost because of vomiting and diarrhea. These persons can
become dehydrated and may need special medical attention. This problem
with dehydration is usually only seen among the very young, the elderly,
and persons with weakened immune systems. There is no evidence to suggest
that an infected person can become a long-term carrier of norovirus.
How do people become infected with noroviruses?
Noroviruses are found in the stool or vomit of infected people. People can
become infected with the virus in several ways, including:
- eating food or drinking liquids that are
contaminated with norovirus;
- touching surfaces or objects contaminated with
norovirus, and then placing their hand in their mouth;
- having direct contact with another person who is
infected and showing symptoms (for example, when caring for someone with
illness, or sharing foods or eating utensils with someone who is ill).
Persons working in day-care centers or nursing homes
should pay special attention to children or residents who have norovirus
illness. This virus is very contagious and can spread rapidly throughout
When do symptoms appear?
Symptoms of norovirus illness usually begin about 24 to 48 hours after
ingestion of the virus, but they can appear as early as 12 hours after
Are noroviruses contagious?
Noroviruses are very contagious and can spread easily from person to
person. Both stool and vomit are infectious. Particular care should be
taken with young children in diapers who may have diarrhea.How long are
People infected with norovirus are contagious from the moment they begin
feeling ill to at least 3 days after recovery. Some people may be
contagious for as long as 2 weeks after recovery. Therefore, it is
particularly important for people to use good handwashing and other
hygienic practices after they have recently recovered from norovirus
Who gets norovirus infection?
Anyone can become infected with these viruses. There are many different
strains of norovirus, which makes it difficult for a person’s body to
develop long-lasting immunity. Therefore, norovirus illness can recur
throughout a person’s lifetime. In addition, because of differences in
genetic factors, some people are more likely to become infected and
develop more severe illness than others.
What treatment is available for people with norovirus infection?
Currently, there is no antiviral medication that works against norovirus
and there is no vaccine to prevent infection. Norovirus infection cannot
be treated with antibiotics. This is because antibiotics work to fight
bacteria and not viruses.
Norovirus illness is usually brief in healthy individuals. When people are
ill with vomiting and diarrhea, they should drink plenty of fluids to
prevent dehydration. Dehydration among young children, the elderly, the
sick, can be common, and it is the most serious health effect that can
result from norovirus infection. By drinking oral rehydration fluids (ORF),
juice, or water, people can reduce their chance of becoming dehydrated.
Sports drinks do not replace the nutrients and minerals lost during this
Can norovirus infections be prevented?
Yes. You can decrease your chance of coming in contact with noroviruses by
following these preventive steps:
- Frequently wash your hands, especially after
toilet visits and changing diapers and before eating or preparing food.
- Carefully wash fruits and vegetables, and steam
oysters before eating them.
- Thoroughly clean and disinfect contaminated
surfaces immediately after an episode of illness by using a bleach-based
- Immediately remove and wash clothing or linens
that may be contaminated with virus after an episode of illness (use hot
water and soap).
- Flush or discard any vomitus and/or stool in the
toilet and make sure that the surrounding area is kept clean.
Persons who are infected with norovirus should not
prepare food while they have symptoms and for 3 days after they recover
from their illness (see food handler information sheet). Food that may
have been contaminated by an ill person should be disposed of properly.
Hand Hygiene in Healthcare Settings
October 25, 2002
Contact: CDC Media Relations
CDC releases new
The Centers for
Disease Control and Prevention (CDC) today released new guidelines that
advise the use of alcohol-based handrubs to protect patients in health
care settings. The new hand hygiene guidelines were released in Chicago
during the 40th annual meeting of the Infectious Diseases Society of
"Clean hands are
the single most important factor in preventing the spread of dangerous
germs and antibiotic resistance in health care settings," said Dr. Julie
Gerberding, director of the CDC. "More widespread use of these products
that improve adherence to recommended hand hygiene practices will promote
patient safety and prevent infections."
CDC estimates that
each year nearly 2 million patients in the United States get an infection
in hospitals, and about 90,000 of these patients die as a result of their
infection. Infections are also a complication of care in other settings
including long-term care facilities, clinics and dialysis centers.
Improving hand hygiene will help prevent the spread of germs from one
patient to another. Data show that health care personnel may be more
inclined to use alcohol-based handrubs because they are more convenient to
use. Recent studies show that these handrubs actually reduce the number of
bacteria on the hands more effectively than washing hands with soap and
"Health care personnel are always on the go which sometimes makes
handwashing with soap and water difficult," said Dr. Steve Solomon, acting
director of CDC's healthcare quality promotion division. "These handrubs
should help promote hand hygiene because they are much more accessible
than sinks, take less time to use and cause less skin irritation and
dryness than many soaps."
The new guidelines
recommend additional steps that administrators can take to increase
adherence to good hand hygiene practices. When deciding what products to
purchase, administrators should consult with health care personnel on
issues like smell, consistency and the amount of skin irritation the
product may cause. If, as expected, hand hygiene products improve hand
hygiene practices, preventing even a few additional health care-associated
infections per year will lead to savings that will exceed any extra costs
for better hand hygiene products.
The hand hygiene
guidelines were developed by the CDC's Healthcare Infection Control
Practices Advisory Committee (HICPAC), in collaboration with the Society
for Healthcare Epidemiology of America (SHEA), the Association of
Professionals in Infection Control and Epidemiology (APIC), the Infectious
Disease Society of America (IDSA).
The hand hygiene
guidelines are part of an overall CDC strategy to reduce infections in
health care settings to promote patient safety. For more information about
the hand hygiene campaign go to
http://www.cdc.gov/handhygiene. For more
information about CDC's seven health care safety challenges go to
Centers for Disease Control and Prevention (CDC) protects people's health
and safety by preventing and controlling diseases and injuries; enhances
health decisions by providing credible information on critical health
issues; and promotes healthy living through strong partnerships with
local, national and international organizations.