The outbreak of gastroenteritis in the Republic can be traced back to Northern Ireland, writes Dr Muiris Houston, Medical Correspondent
Small round structured viruses or SRSVs are a recognised cause of gastroenteritis in the community, in hospitals and in nursing homes but this year's "explosion in cases" is unusual.
SRSVs are particularly resistant microbes and, unusually for a bug which affects the gastrointestinal tract, it is spread by both the airbourne route as well as the more usual person-to-person contact. This is undoubtedly a factor in the community spread of the illness.
The first cases of SRSVs were reported in Northern Ireland in early December. The outbreak - in hospitals and residential homes - caused the temporary closure of wards and also affected staff. Belfast's Royal Victoria Hospital was forced to shut two wards over the New Year period, as was the Lagan Valley Hospital in Lisburn. Altnagelvin Hospital in Derry had 25 patients affected in January, with 50 staff members absent from work due to gastroenteritis.
The virus then spread southwards to a hospital in Co Louth, resulting in the closure of a medical ward for some days in January. At least 49 people were struck by the illness. SRSVs have been positively identified from some of the cases.
A hospital for older people in the midlands was next to be affected, followed by the most recent reported outbreak in the regional hospitals in Mullingar and Mayo General Hospital, in Castlebar - the town's Sacred Heart Hospital which caters mainly for older people, has identified 26 patients and 10 staff with the virus.
Viral gastroenteritis is also affecting people in the community with anecdotal evidence from GPs of illness hitting different areas.
Most people will be able to cope without medical help with what is a short, but very sharp illness. The vomiting is severe - often projectile - and the diarrhoea unpleasant, but most of us will be clear of symptoms in 48 to 72 hours.
For older people and those whose immune systems are compromised by other diseases, SRSVs 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.
Between June and the end of December 2001, the National Disease Surveillance Centre received reports of 37 outbreaks of gastroenteritis in the State. Fifteen of these were considered to be caused by a virus; five were subsequently confirmed as SRSVs. These figures tie in with the international experience, which shows SRSV type viruses account for a third of non-bacterial infections of the gut.
The virus is known to cause in the region of one million cases of gastroenteritis in the UK each year. Contaminated oysters and water have been identified as potential sources for the infection; however because it is such a "hardy" virus, it is able to survive in the air and is transmitted effectively from person to person.
There are a number of reasons for this extensive outbreak: one is that SRSVs are not as common historically as other tummy bugs and so we have not had a chance to develop an immunity to the virus; secondly, viruses mutate rapidly and so it is virtually impossible to maintain immunity to these bugs, even for those previously infected, from year to year. And because SRSVs can be transmitted in the air as well as by the more usual hand-to-hand route, it is highly infectious.
Treatment consists of taking plenty of clear fluids. Antibiotics are not necessary and the disease is self-limiting, without the need for specific medical treatment in the majority of cases.
It is expected to be next week before elective surgery recommences at the Mayo General Hospital in Castlebar, which has been affected by an outbreak of the highly contagious virus that causes gastroenteritis.
A spokesperson for the Western Health Board said last night the problem at the hospital was under control. Infection control procedures were in place and visits to patients were being discouraged.
The Sacred Heart Hospital in Castlebar, which caters mainly for older people and which has also been affected by the virus, has put strict infection control procedures in place.