Appeals to the public not to visit patients at the Midland Regional Hospital in Mullingar and at Mayo General Hospital, Castlebar were renewed yesterday as a gastroenteritis virus continued to affect the region.
Elective surgery is still postponed at both hospitals.
Spokeswomen for the Midland and Western Health Boards said the public had co-operated very well with appeals not to visit the hospitals at the weekend unless absolutely necessary.
However, with the virus still affecting people in the community in both regions, it was necessary to continue the appeal to avoid bringing more infection into the hospitals. About 30 patients and staff at Mullingar and about 16 patients in Mayo General have already been infected.
In addition, about 26 patients and 12 staff were infected in the Sacred Heart Hospital for older people in Castlebar.
In Tallaght, Dublin, a crèche in which 12 children were infected last week re-opens today. Eighteen patients and staff who got a "very mild" infection with the virus in a long-stay ward in Beaumont Hospital, Dublin, last week have recovered, according to the Eastern Regional Health Authority.
Small numbers of cases have been reported in three long-stay facilities for older people in Dublin but most were diagnosed last week.
The North Eastern Health Board, which had an outbreak in January, said it was now aware of only one case, in Cavan.
Other health boards were not aware of any outbreaks of the SRSV virus.
The outbreak is believed to have originated in Northern Ireland where hospitals and homes were affected in December.
The virus causes severe vomiting and diarrhoea but most people are clear of symptoms in two to three days. It is not believed to have any adverse long-term effects on health.
People whose immune systems are vulnerable and older people may need special nursing and intravenous fluids. Treatment consists of taking plenty of fluids. Antibiotics are not necessary and most people affected by the virus do not need medical treatment.
The virus is strong and able to spread by a number of routes. A study of an outbreak on board a cruise ship, reported in the Lancet in 1989, found that the risk of gastroenteritis among passengers who had shared toilet facilities was twice that of those who had a private bathroom. The more people sharing a bathroom the greater the risk of transmission.
It also found that patients who had vomited in their cabins were more likely to have had cabin-mates who subsequently became ill than were patients who had not vomited - suggesting that the virus spreads by means of airborne droplets or person-to-person contact.
Contaminated oysters and water are other possible sources of infection.