Enhanced surveillance of initial cases of pandemic H1N1 2009 influenza in Ireland, April-July 2009.

From 28 April to 18 July 2009 there were 156 cases of pandemic H1N1 2009 influenza confirmed in Ireland. During this time, Ireland was in containment phase, and detailed case-based epidemiological information was gathered on all cases presenting in the community and acute health care setting. Active case finding was performed among contacts of cases. Eighty percent of cases were in people less than 35 years of age and 86% were imported. The most frequent symptoms were fever, sore throat, myalgia and dry cough. Nine people were hospitalized, no fatalities occurred.