Irish Times Medical Correspondent, Dr Muiris Houston, examines the 'vomiting bug', its treatment and effect on people.
What does the bug do?
The small round structured virus (also known as Norwalk-like virus) is a recognised cause of gastroenteritis both in the community and in institutions such as hospitals and nursing homes.
How is it spread?
The virus is a particularly resistant microbe and, unusually for a bug which affects the gastrointestinal tract, is spread both by the airborne route and the more usual person-to-person contact. This is undoubtedly a factor in the spread of the illness through hospitals and hotels in the State.
If I get it, how will I feel?
Vomiting can be severe - and is often projectile in nature - and the diarrhoea unpleasant, but most of those affected will be clear of symptoms in 48 to 72 hours. Other symptoms include abdominal pain and a low-grade fever.
Will I need a doctor?
Most people will be able to cope without medical help with what is a short but very sharp illness. For the elderly and those whose immune systems are compromised by other diseases, the bug can be more serious. While there is no specific treatment for the virus, these patients may require more intensive treatment in the form of intravenous fluids and special nursing. There have been no reported fatalities to date and the illness does not have long-term health effects.
What's the treatment?
Plenty of clear fluids. Antibiotics are not necessary and the disease is self-limiting (no need for medical treatment) in the majority of cases.
Will the outbreak go on a long time?
There are a number of reasons for this year's prolonged outbreak: one is that SRSV is not as common historically as other stomach bugs, so we have not had a chance to develop an immunity. Also, viruses mutate rapidly, so it is virtually impossible to maintain immunity, even for those previously infected, from year to year. Because SRSV can be transmitted through the air as well as person-to-person, it is highly infectious.