Denmark today became the first northern European country to report a confirmed case of swine flu, as case numbers continued to grow worldwide, according to dpa. The male patient was in hospital and kept in an isolated unit, Danish officials said. Meanwhile the European Centre for Disease Prevention and Control (ECDC) reported midday Friday that 28 people in six other European countries were confirmed to have been infected with swine flu. The confirmed European cases were in Britain, Germany, Spain, Austria, Switzerland, and the Netherlands, the ECDC said. In addition there were two suspected cases in France and one in Ireland as well as seven probable cases in Britain, the agency said. The ECDC stressed that the European cases were "almost entirely among those returning from Mexico." The ECDC recommends using the term A(H1N1) for the virus - just as the World Health Organization does. ECDC chief scientist Johan Giesecke said Friday that sequencing of the new virus suggested that while its "closest relative was swine flu" it was "misleading to call it the swine virus." "There is no link directly so far to infection in pigs," he said. Professor Angus Nicoll, head of the ECDC influenza programme, said work was continuing to estimate the effects of the outbreak, including using infection rates compiled from previous influenza pandemics in 1918, 1957 and 1968. The information from those events suggested that some 25-30 per cent of people could get sick while one third would be infected but not show any symptoms, Nicoll said. Of those who became sick, some 4 per cent might "benefit from hospital care," he said, but it was too early to forecast how the current outbreak would impact European countries. A positive factor was the time of year with a slowing down of influenzas, and that most cases - at least based on developments to date in the United States - were mild, Nicoll said. The first European case was reported April 27. The breakdown of the 13 cases that have been studied in more detail indicated the patients were from age 3 to 41, affecting males and females equally. The confirmed cases outside Europe tallied 454 as of Friday morning including 312 cases in Mexico and 12 deaths, 109 cases and one death in the United States, 28 in Canada, and three in New Zealand. The ECDC tally did not include a case reported from Hong Kong, Asia's first case of swine flu. New laboratory results released by the Health Ministry in Mexico contributed to an increase over Thursday, the ECDC statement said. In New Zealand, 13 cases were defined as probable pending further tests while two cases reported from Costa Rica and one from Peru were removed "pending validation," the agency said. The ECDC with headquarters in Sweden began to operate in 2005, and groups the bloc as well as several non-EU members.