Derry is in the grip of a swine flu alert following the death of a previously healthy man from the deadly H1N1 virus.

Those with symptoms of the influenza strain are being urged to seek medical assistance after it emerged that a 52 year-old Ballykelly man - who was not in an 'at risk' category - died in Altnagelvin Hospital on December 29. It's understood that the victim was admitted to the hospital on Christmas night after collapsing at home.

The Western Health Trusts Medical Director Dr Anne Kilgallen confirmed that swine was the "most commonly" diagnosed influenza strain locally in the last fortnight. "In the last week of 2010 there were 213 cases of flu reported in the region and 185 of those were Influenza A H1N1." She encouraged those in "at risk" groups such as pregnant women, the elderly and those with chronic disease to get vaccinated.

Health bosses are warning that the spread of the virus could escalate in the coming weeks, a fear exacerbated by the return of thousands of pupils to school after the Christmas break. A spokesman for the Western Education and Library Board said there are "currently no plans to close any schools", although the move has not been ruled out. "The Board will be advised by the Public Health Agency should such a decision need to be taken," he added.

Geraldine Hillick, Western Trust Director of Acute Services, said the large number of patients presenting with respiratory illness "is having an impact on hospital services". She added that the Trust's priority is to minimize the spread of the virus.

"In situations where there are a number of patients with an infectious illness they are treated in isolation including in cohort bays in ward areas as part of measures to prevent the spread of infection. Currently patients with influenza or suspected influenza are being treated in a number of different ward areas, depending on their clinical need."

Some planned operations have had to be deferred to enable theatre staff to work in an intensive care environment to support the maintenance of critical care services to those patients who need it most. Patients affected will be contacted directly by the hospital.

Ms Hillick added that the situation is being reviewed on a daily basis and that surgery is only being deferred "where necessary".

She urged anyone visiting patients in the hospital not to do so if they feel unwell.

Derry GP Dr Tom Black appealed to the public to be alert to the signs specific to the H1N1 virus.

which he said was the "predominant" strain of flu he has treated in recent weeks.

"In addition to normal flu symptoms, swine flu can cause shortness of breath, chest pains, confusion, high temperature which won't settle down and the coughing up of dirty phlegm."