The group of 11 friends, who left on June 19 for a week’s break, stayed at the Central City apartments in San Antonio.

Before the end of the holiday, three of them showed flu symptoms and were confined to bed.

Sleeping four to a room, there was little they could do to stop the virus from spreading.

One of those affected was 19-year-old Stephen Ree who said, “My symptoms started on the Tuesday after we got there. I had a sore head, sore chest and really, really sore back and shoulders.

“By the next day, I physically could not get out of my bed, my back and shoulders were so sore.

“The rest of us has bad coughs and sore chests and all of us suffered one way or another.”

Ibiza, it soon emerged, was not really up to speed as far as swine flu is concerned.

Stephen added, “When I first started getting the symptoms, I went to the pharmacy and told them what was happening. They never mentioned swine flu.

“Nobody over there was aware it was going on. We spoke to the reps and they said that, as far as they were aware, there was nothing going around.

“We were all joking about it being swine flu. I don’t know how anyone picked it up.”

Stephen said members of the group were contacted by NHS Tayside when they returned. Five swine flu cases were confirmed, five were given the all clear and one was waiting to hear.

Stephen is now over the worst although he is still confined to his home.

He added, “I’m still drowsy, have a sore chest and a bad cough, but it’s not as bad as it was over there.”

Tayside NHS confirmed five cases of travel-related swine flu in Tayside, but declined to release any details about them.

However, Dr Drew Walker, director of public health, said the local health service was well-placed to deal with Wednesday’s UK transition to the treatment phase of coping with pandemic flu.

The new status, he said, marked a move away from the containment phase and means an end to routine testing of possible cases in favour of surveillance with numbers reported on a weekly basis.

Patients will still be prescribed antivirals if they contract the H1N1 virus.

Dr Walker said, “This move to the treatment phase does not mean the virus is getting more severe or that there is cause for alarm. It simply means we are seeing a rise in the number of cases and are adapting our approach to dealing with this.”