Health chiefs in Belfast were today investigating a rise in the number of illnesses associated with a debilitating bug which can infect water supplies.
The Eastern Health and Social Service Board said it was working with the North's Water Service and environmental health officers to establish why the number of illnesses linked with cryptosporidium had risen in the city.
The cryptosporidium parasite can cause vomiting and chronic diarrhoea and is particularly debilitating for the elderly, very young and infirm.
There was an outbreak last August in the Poleglass and Twinbrook area on the outskirts of Belfast which affected water supplies used by about 100,000 people.
But the Eastern Health and Social Services Board said in a statement today most people suffering illnesses related to cryptosporidium in the latest outbreak were from Belfast.
It stressed there was no link with last year's cryptosporidium outbreak.
"There is an expected seasonal increase in cases of cryptosporidium at this time of the year. However in the current year the increase is greater than usual," the board said.
"The board therefore recommends good hygiene practice - especially hand-washing before eating and avoidance of handling or preparing food for others when ill.
"It is also important to reinforce existing advice to those people with severely impaired immunity - for example, AIDS, those on chemotherapy and transplantations - that they should continue to boil all water, including bottled water, before consumption."
The board said people who developed severe diarrhoea should call their GP immediately.
PA