Swine fever: it’s spreading but it may not be that bad

British health authorities have confirmed the first known case of someone contracting the swine fever virus within the UK rather than in Mexico. He is Graeme Pacitti, 24, who was in contact with the Scottish couple Iain and Dawn Askham before they were diagnosed with the virus after honeymooning in Cancun.

Pacitti is confined to his home in Falkirk. He told the BBC by mobile phone that he was "really disappointed" to have the fever confirmed by the Health Protection Agency (HPA) laboratory in north London.

Pacitti's situation came to light as more British cases were confirmed within travellers from Mexico and the Askhams were sent home from hospital, having fully recovered. They told reporters they probably contracted the virus on their flight back from Cancun, when they were surrounded by passengers coughing and sneezing.

The government's chief medical officer, Prof Sir Liam Donaldson, said yesterday that Britain is likely to see "many more cases" of swine flu confirmed. However, he stressed that all indications are that people are making a good recovery. He said he was "concerned, but not alarmed" by the decision this week of the World Health Organisation to raise the global alert level to phase five, one short of a full-blown pandemic.

Donaldson is not the only scientist who believes that a pandemic need not necessarily be fatal. Prof Wendy Barclay, an influenza virologist at Imperial College who has been studying the samples from British cases, told Channel 4 News on Thursday that the virus's genes are showing none of the signatures that would suggest a severe strain.

In short, swine flu could spread across the world, but the illness it causes could be relatively mild. Her research also suggests that early fears that young, fit people aged between 25 and 40 were most at risk may be unfounded.

In Mexico, the source of the outbreak, 168 deaths from swine flu are suspected - but only 12 have been fully verified so far - and the number of confirmed cases is about 300. Health Secretary Jose Angel Cordova said on Thursday that new confirmed cases were leveling off. "The fact that we have a stabilisation in the daily numbers, even a drop, makes us optimistic," he said.

Outside Mexico, the swine fever virus has now been detected in 13 other countries, with Holland, Switzerland, Denmark and Hong Kong joining the United States, Canada, Costa Rica, Spain, Germany, Austria, Israel and New Zealand as well as the UK.