Norwalk Virus

Topics: Gastroenteritis, Norovirus, Diarrhea Pages: 5 (742 words) Published: August 13, 2008
Norwalk Virus

As the summer season is in full gear now a particular virus is looming in the

horizon. This virus is an important cause of acute gastroenteritis in humans and is

the most frequently implicated cause of outbreaks of viral gastroenteritis

worldwide. Noroviruses are a group of single-stranded RNA viruses in the family

Caliciviridae that cause acute gastroenteritis in humans.(1) Norwalk virus is the

prototypical strain in the genus. Noroviruses cause an estimated 20% of all viral

gastroenteritis cases in persons older than 24 months. (1).

Norwalk virus was first associated with gastroenteritis in 1972. It was

identified by electron microscopy of stool samples that had been saved from a

1968 gastroenteritis epidemic that occurred in Norwalk, Ohio.(2) In a 2-day

period, acute gastroenteritis developed in 50% of 232 students or teachers

in an elementary school.(2) The virus initially was labeled as a small, round,

structured virus, and it was named after the city in which the outbreak occurred(2) .

Recently, norovirus infections have made news as the cause of several outbreaks

of gastroenteritis on cruise ships.

The viruses are transmitted via the fecal-oral route. The most common

routes of infection included contact with an infected individual or contact with

contaminated food and water.(3) Noroviruses can also be spread via particles

aerosolized with vomiting. The viruses are highly contagious. Infection is

characterized by damage to microvilli in the small intestine, causing malabsorption.

Vomiting is related to a virus-mediated change in gastric motility and delayed

gastric emptying.(4)
Symptomatic gastroenteritis typically develops 24-48 hours after ingestion

of contaminated food or water or after contact with an infected individual. Each

episode is short-lived, lasting approximately 1-2 days.(4)

Symptoms include: nausea and vomiting, watery diarrhea, abdominal

cramps, headache, low-grade fever, and pain all over (myalgia). (5)

Several causes in catching the noro virus include: Contaminated

water supply, frequently implicated foods include salads, cake frosting,

clams, oysters, and meats.(4) Viral spreading can occur in vomitus and feces.

Contamination can occur through an infected water supply, undercooked foods, or

improper hand washing by an infected food preparer. Viral spreading can occur

during profuse vomiting and diarrhea, secondary transmission commonly occurs

among close contacts of the infected person. Cruise ships are particularly vulnerable

because of frequent changes in the passenger cohort, relative crowding, and the

difficulty in performing decontamination during short periods at shore. (3)

Certain lab tests that can detect this virus. This can be achieved with a

polymerase chain reaction (PCR) or an electron microscopy. Since these tests can

be costly, severe cases of gastroenteritis with suspected dehydration, some lab studies

are indicated such as serum electrolytes or creatinine levels to see if there is any severe


In treating this virus, outpatient therapy is typically sufficient such as oral

rehydration, rest, contact exposure precautions (increase hand washing).

There is no medication prescribed to this virus since it is usually self-limited

to 24-48 hours. Antidiarrhea agents may be used sparingly but it should be avoided in children.

Preventative measures through appropriate hand washing and disposal of

infectious materials.

Disease transmission may be decreased with education regarding hand-

washing for food preparers, daycare employees, resort/cruise guests, and family

or close contacts of infected individuals.

In conclusion, summer will be great only if that particular virus can stay away

from our lives. Always remind people to wash their hands by singing Happy

Birthday and summer...
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