ه‍.ش. ۱۳۹۱ بهمن ۷, شنبه

=== Some Facts about the New Strain of Norovirus ===

A new strain of stomach bug sweeping the globe and making people sick in the US, Canada, Japan, Western Europe, and other parts of the world. It was first identified last year in Australia and called the Sydney strain.
The virus, which is actually a group of viruses that are the most common cause of epidemic gastroenteritis, has been bandied about in the past as an interchangeable term for the stomach flu, but the phrasing can be incredibly misleading for the public. The Flu is a respiratory virus, while Noro takes place in the gastrointestinal system, and the patients don't get a cough or a sore throat with norovirus. Once known as Winter Vomiting Disease and characterized by nausea, vomiting and diarrhea, norovirus tends to take place seasonally, coming on very suddenly and lasting for approximately 24 to 48 hours. As winter sets in and people stick to the indoors, without fresh air circulating via open windows, the virus is more likely to spread

What are Noroviruses

The Noroviruses have likely been around for thousands of years, but their existence was only discovered in 1972 by Dr. Albert Kapikian while studying the infectious causes of a gastrointestinal outbreak in Norwalk, Ohio. Using an electron microscope, he found an incredible amount of small, round-structured creatures no more than a few dozen billionths of a metre in diametre. He was fascinated not only because he had found a new type of virus, but because the culprit caused one of the most egregious attack on the human condition.
Noroviruses are a genetically diverse group of single-stranded RNA, non-enveloped viruses in the Caliciviridae family. The viruses are transmitted by fecally-contaminated food or water; by person-to-person contact; and via aerosolization of the virus and subsequent contamination of surfaces. Noroviruses are the most common cause of viral gastroenteritis in humans, and affect people of all ages
Norovirus infection is characterized by nausea, forceful vomiting, watery diarrhea, and abdominal pain, and in some cases, loss of taste. General lethargy, weakness, muscle aches, headache, coughs, and low-grade fever may occur. The disease is usually self-limiting, and severe illness is rare. A small number of people die, mostly the very young, the elderly, and persons with weakened immune systems
Winter vomiting bug is a common term for noroviruses in the UK, because the virus tends to cause vomiting and to spread more easily in winter, when people tend to spend more time indoors and near to each other
After infection, immunity to norovirus is usually incomplete and temporary. Outbreaks of norovirus infection often occur in closed or semiclosed communities, such as long-term care facilities, overnight camps, hospitals, prisons, dormitories, and cruise ships, where the infection spreads very rapidly either by person-to-person transmission or through contaminated food. Many norovirus outbreaks have been traced to food that was handled by one infected person
Norovirus is rapidly inactivated by either sufficient heating or by chlorine-based disinfectants, but the virus is less susceptible to alcohols and detergents, as it does not have a lipid envelope
The genus name Norovirus is derived from Norwalk virus, which causes approximately 90% of epidemic nonbacterial outbreaks of gastroenteritis around the world, and may be responsible for 50% of all foodborne outbreaks of gastroenteritis in the United States

Ten Top Tips You Need to Know about Norovirus

 Where does it come from? The virus is spread through an infected person's feces or vomit, and often by unwashed hands

 Where can You get it? The most common places for norovirus to spread are residences where many people are living together, nursing homes, for example, or cruise ships

 What are the Symptoms? The clinical syndrome is characterized by nausea, vomiting and diarrhea, though for some, it can also include a fever and abdominal pain. It comes on very suddenly, usually within 10 hours of transmission, and lasts one to three days. After three days, it is no longer contagious

Who's at Risk? Anyone can get norovirus, but it can be a particularly bad illness for the very young, and the very old. Healthy people who get it feel awful, but they recover quickly. The problem is when it combines with other ailments. For very old people who might have other health problems, it can have serious effects, while very young people can dehydrate much more quickly. Furthermore, the virus particularly likes people with the blood group O, which constitutes about 45 per cent of the population. This is thanks to the receptor the virus attaches itself to. If you have another blood type, you can still get norovirus, but the disease will likely not be as severe

 What can You do if You Contract Norovirus? It is wise to lay low and wait for yourself to get better. There's no treatment, and while medical professionals advise keeping fluids up, many physicians acknowledge this can be difficult, given the nature of the illness

 What can People do to Protect themselves? You will want to practice good hygiene in order to reduce the possibility that you will ingest the virus, recommends Dr.Gerald Evans from Queen's University, and of course, try to avoid being in a circumstance where you can get the virus

 Why is it such a Concern? The biggest problem, notes Dr. Evans, is that the virus is very transmissible, and can easily pass from person to person. It's also quite the trial on your health. "It's very traumatic," says Dr. Evans. "It's amazing how fast it starts, and it's amazing how bad you feel for at least a day or two". Most people who get it would rather have anything else

 What is the Difference between Norovirus and the Flu? The flu is an entirely different illness than norovirus. The flu takes place in the respiratory system, while norovirus is a gastroenterological illness. Besides the lack of cough and cold in norovirus, it also has a much short lifespan: Three days vs. the flu's five to seven-day stint

 What is the Difference between Norovirus and Norwalk? Norwalk is an old term for norovirus. Viruses are always named geographically, and the first norovirus was discovered in Norwalk, Ohio, so it was given that name. It's been since changed to give the group of viruses the name Norovirus. It should also be noted that in addition to "Norwalk agent" and "Norwalk virus," the virus previously has been called "Norwalk-like virus," "small, round-structured viruses" (SRSVs), and "Snow Mountain virus". Common names of the illness caused by noroviruses still in use include "winter vomiting disease," "winter vomiting bug," "viral gastroenteritis," and "acute nonbacterial gastroenteritis." It also colloquially is known as "stomach flu," but this actually is a broad name that refers to gastric inflammation caused by a range of viruses and bacteria

 Are there any Long-Term Effects? "As far as we know, there are no long-term effects, it's a very self-limited illness," says Dr. Evans. The biggest, scariest thing about noro is that you're never immune to it, because there are a bunch of different strains. Once you get it, you can pretty well guarantee you will get it again


Hand washing with soap and water is an effective method for reducing the transmission of norovirus pathogens. Alcohol rubs may be used as an adjunct, but are less effective than hand-washing, as norovirus lacks a lipid viral envelope. Surfaces where norovirus particles may be present can be sanitised with a solution of 1.5% to 7.5% of household bleach in water, or other disinfectant effective against norovirus
In health-care environments, the prevention of nosocomial infections involves routine and terminal cleaning. Nonflammable alcohol vapor in CO2 systems are used in health care environments where medical electronics would be adversely affected by aerosolized chlorine or other caustic compounds
Ligocyte announced in 2007 that it was working on a vaccine and had started phase 1 trials.  As of 2011 a monovalent nasal vaccine had completed phase I/II trials, while bivalent intramuscular and nasal vaccines were at earlier stages of development

Manouchehr Saadat Noury, PhD

Sifferlin, A. (2013): Online Article on New Strain of Norovirus Is Circulating In The US
Tetro, J. (2013): Online Article on When it Comes to Germs, Norovirus is Public Enemy Number One
The Huffington Post Canada Website (2013): Online Article on Things You Need To Know About Winter Vomiting Disease
Various Sources (2013): Online News and Articles on the New Norovirus Strain
Wikipedia (2013): Online Article on Norovirus