According to a recent Health Protection Agency (HPA) report, the Norovirus outbreaks in hospitals reporting scheme recorded 213 suspected and confirmed Norovirus outbreaks occurring between weeks 09 and 12 2010. Seventy-seven percent (163) of these outbreaks involved some kind of ward closure or restriction to admissions and sixty-four percent (136) were laboratory confirmed.
What is Norovirus?
Norovirus (formerly called Norwalk agent) is an RNA virus that causes approximately 90% of epidemic non-bacterial outbreaks of gastroenteritis around the world, and may be responsible for 50% of all foodborne outbreaks of gastroenteritis in the US. Norovirus affects people of all ages. The viruses are transmitted by faecally contaminated food or water and by person-to-person contact.
There is an inherited predisposition to infection, and individuals with blood type O are more often infected, while blood types B and AB can confer partial protection against symptomatic infection. Outbreaks of Norovirus infection often occur in closed or semi-closed 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 outbreaks have been traced to food that was handled by one infected person.
Is Norovirus Dangerous?
Common names of the illness caused by Noroviruses are winter vomiting disease, viral gastroenteritis, and acute non-bacterial gastroenteritis, also colloquially known as “stomach flu”—a broad name that refers to gastric inflammation caused by a range of viruses and bacteria.
When a person becomes infected with Norovirus, the virus begins to multiply within the small intestine. After approximately 1 to 2 days, Norovirus symptoms can appear. The principal symptom is acute gastroenteritis that develops between 24 and 48 hours after exposure, and lasts for 24–60 hours. The disease is usually self-limiting, and characterised by nausea, vomiting, diarrhoea, and abdominal pain; and in some cases, loss of taste. General lethargy, weakness, muscle aches, headache, and low-grade fever may occur.
Severe illness is rare: although people are frequently treated in A&E, they are rarely admitted to the hospital. The number of deaths from Norovirus in the US is estimated to be around 300 each year, with most of these occurring in the very young, elderly and persons with weakened immune systems. Symptoms may become life-threatening in these groups if dehydration is ignored or not treated.