Norovirus (Norwalk Virus)
Date: 3 سال قبل
author: AmirAbad
Norovirus
(Norwalk Virus)
Noroviruses
(NoV) are a genetically diverse group of single-stranded positive-sense
RNA, non-enveloped viruses belonging to the
family Caliciviridae. According to the International Committee
on Taxonomy of Viruses, the genus Norovirus has one species, which is
called Norwalk virus.
Norovirus
is the most common cause of gastroenteritis. Infection
is characterized by non-bloody diarrhea, vomiting, and stomach
pain. Fever or headaches may also occur. Symptoms usually develop 12
to 48 hours after being exposed, and recovery typically occurs within 1 to 3
days. Complications are uncommon, but may include dehydration,
especially in the young, the old, and those with other health problems.
The virus is
usually spread by the fecal–oral route. This may be through
contaminated food or water or person-to-person contact. It may also spread
via contaminated surfaces or through air from the vomit of an
infected person. Diagnosis is generally based on
symptoms.
Prevention
involves proper hand washing and disinfection of
contaminated surfaces. Alcohol-based hand sanitizers are not
effective against the Norovirus, this is due to Norovirus being a non-enveloped
virus. There is no vaccine or specific treatment for norovirus. Management involves supportive care such as
drinking sufficient fluids or intravenous fluids.
Signs
and symptoms
Norovirus
infection is characterized by nausea, vomiting, watery diarrhea,
abdominal pain, and in some cases, loss of taste. A person usually develops
symptoms of gastroenteritis 12 to 48 hours after being exposed to
norovirus. General lethargy, weakness, muscle aches, headaches, and low-grade
fevers may occur. The disease is usually self-limiting, and severe illness
is rare. Although having norovirus can be unpleasant, it is not usually
dangerous, and most who contract it make a full recovery within two to three
days.
Norovirus
can establish a long term infection in people who are immunocompromised,
such as those with common variable immunodeficiency or with a
suppressed immune system after organ transplantation. These
infections can be with or without symptoms. In severe cases, persistent
infections can lead to norovirus‐associated enteropathy, intestinal
villous atrophy, and malabsorption.
Diagnosis
Specific
diagnosis of norovirus is routinely made by polymerase chain
reaction (PCR) assays or quantitative PCR assays, which give
results within a few hours. These assays are very sensitive. Tests
such as ELISA that use antibodies against a mixture of norovirus
strains are available commercially.
Treatment
There
is no specific medicine to treat people with norovirus illness. Norovirus
infection cannot be treated with antibiotics because it is a virus. Treatments
aim to avoid complications by measures such as the management of
dehydration caused by fluid loss in vomiting and diarrhea, and to
mitigate symptoms using antiemetics and antidiarrheals.
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