When Caitlin Brooker ended up in hospital with swine flu, it all happened very rapidly. The 21-year-old from a village in Leicestershire began to feel unwell with pains in her back on Sunday, two weeks ago.

“By the evening I was really ill, delirious,” said Brooker. “My lips turned black and I was slipping in and out of consciousness.”

Like many badly affected by the virus, Brooker’s defences were weakened: she already has problems with asthma and her thyroid. What illustrates how the swine flu pandemic is moving into a new phase is not so much her illness as the reaction to it.

“It was very scary and my mother called NHS Direct. Then some medics arrived, all masked. I was taken to hospital and put in an isolation room.

“My mum was panicking. I’d never been so ill. Some of the nurses were lovely, but some were horrible. They wouldn’t come in. They shouted through the door.”

Along with the virus, panic is also spreading, even among health workers. Brooker claims that one nurse even “ran in, shoved my food on my lap and ran out again”.

The public are also edgy. When Brooker was discharged two days later, she was told to wear a green surgical mask and keep it on until she got home. “The looks I got in the lift and car park were unreal,” she said. “People took big steps around me and one lad shouted, ‘She’s got swine flu!’.”

Since then the mood has grown even more feverish. In the past week an estimated 55,000 more people have caught the virus in the UK and 12 more have died. While experts are clear that the present swine flu is no more deadly than ordinary flu, the speed of its spread has startled them.

The outbreak here is far more extensive than in other European countries. According to the European Centre for Disease Prevention and Control, the UK has 10 times more swine flu cases than anywhere else in Europe.

Professor Alan Hay, director of the World Health Organisation’s influenza centre in Mill Hill, northwest London, said: “The virus has taken us by surprise. We previously expected it wouldn’t reach this level in the summer, but what we’re seeing now is probably similar to what was transpiring in the US in the last two months.”

Professor Neil Ferguson, an epidemiologist at Imperial College London, agrees. “The biggest surprise is how well this virus has been spreading in summer,” he said. “Right now case numbers are roughly doubling every week, and that’s a faster rate of growth than I might have anticipated.”

Part of the reason is that Britain is a hub for international air travel and millions of Britons now regularly go on holiday abroad, particularly to America, which has been badly hit, with some picking up swine flu along the way. Couple that with a crowded isle and you have ideal conditions for a new H1N1 virus to arrive and spread.

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