Norovirus

There are many possible causes of diarrhea and vomiting (gastroenteritis) but the most common are viruses. This is why most cases of diarrhea get better on their own, without any specific medications or antibiotics. The Norovirus, previously known as Norwalk virus, is a common cause of gastroenteritis outbreaks. This virus first discovered in Norwalk, Ohio, has been at the root of several epidemics or outbreaks of gastroenteritis. These viruses can infect people of any age and usually cause profuse watery diarrhea, vomiting and fatigue. The infection lasts a few days and there is no specific treatment.

Over the last 5 years, this virus has been one of the leading causes of outbreaks in travelers returning from tropical vacation destinations and cruise ships as well in schools, daycares and long term care facilities and homes. Norovirus is highly infectious and tends to occur in clusters, or “outbreaks”. It spreads from one person to another through direct or indirect contact with infected feces or vomit. More rarely, it can also be transmitted by drinking water, which contains the virus, or by eating food contaminated by this virus.   The virus is especially contagious in close or confined spaces like planes, buses, meeting rooms and cruise ships. Symptoms usually develop within 1-2 days after contact with an infected person.  When such enteric outbreaks occur, food poisoning or a food borne illness may be initially suspected. However with Norovirus outbreaks, further investigation fails to find a particular food as a source.  

Confirmation of Norovirus infection

Confirmation of a Norovirus infection is possible through a specific stool test. A blood test can also confirm the infection. These tests are usually performed during epidemic situations (not routinely) so that authorities can determine the specific cause of the outbreak.

The treatment of Norovirus infection

Fortunately, in most cases, the treatment is simply to drink adequate amounts of fluid, depending on the severity of the symptoms. Recently, doctors have modified their approach to mild cases of diarrhea and usually do not change the diet at all. In moderate illness, specific liquids are used called "oral rehydration solutions". Never give only water to a person who is vomiting or has diarrhea. This can be dangerous. The body needs a certain (right) amount of salt and sugar, which are not in adequate amounts in water nor in watered-down juice or soft drinks. Only "oral rehydration solutions" such as Pedialyte or Infalyte contain the right amount of sugar and salt. Generally milk can be continued as long as it does not make the diarrhea worse.  In severe cases of diarrhea (and/or vomiting) and dehydration, and they are relatively rare, the only treatment is the administration of intravenous fluids in a hospital setting. Because each person is different, treatment is based on the individual situation.

Prevention of Norovirus infection

The prevention approach to Norovirus induced gastroenteritis is the same as with the other forms of viral gastro-intestinal infections: hand washing, before and after contact with any infected individual, and decontamination of areas such as toilets, sinks and other objects that have come into contact with infected stool or vomit.