Norwalk Virus
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,
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,
Bibliography: Associated with nor virus on cruise ships-United States , 2002 MMWR Morb Mortal Wkly Rep 2002 Dec 13; 51 (49): 1112-5