Fears have been raised that swine flu is circulating in Edinburgh after two students tested positive for the disease but have not been in contact with any known cases or travelled to the United States or Mexico.
By Rebecca Smith, Medical Editor
Last Updated: 6:48PM BST 29 May 2009
The two students, a 20-year-old man and a 21-year-old man from Greece, who both study in Edinburgh, developed symptoms of the disease last Sunday while in Scotland.
They were tested in Greece and found to be positive for H1N1 swine flu but they have not travelled to countries where the disease is widespread and to their knowledge have not been in contact with anyone confirmed or suspected of having the disease.
The cases could mark a significant shift in the swine flu outbreak in Scotland as doctors in Greece have questioned whether the virus is spreading more widely but current testing methods are not detecting it.
A spokesman for Heriot Watt University, where the two students are studying, said: "There were seven potential contacts who have all been cleared. We are continuing to operate as normal and we are in close contact with the relevant health and governmental bodies who are monitoring the situation."
Health Protection Scotland is still investigating the source of the infections, a spokesman for the agency said.
There are also three cases in England where the source of the infection has not yet been established. One in the North West and two in the East of England region.
Clusters of cases have occurred in schools in London and Birmingham and earlier this week Eton College confirmed it will remain closed for an extra week after half term after a pupil tested positive.
Ministers and health officials have said that if swine flu continues to spread it is to be expected that so-called 'de novo' cases will appear.
However a spokesman said the Health Protection Agency said: "There is currently no widespread community transmission."
Dr Takis Panagiotopoulos, of the Hellenic Centre for Disease Control and Prevention (KEELPNO), Athens, Greece, has written a research paper published online in Eurosurveillance, the scientific journal on the epidemiology of communicable diseases in Europe.
He said the 21-year-old patient had not travelled outside of Scotland and had not been in contact with any known H1N1 cases to his knowledge. "However he met a large number of people, mainly students and attended three student parties. Furthermore he spent a lot of time with his two room-mates and at least two other close friends, one of whom is case two."
The research paper adds that the source of the infection could be an as yet unidentified traveller returning from Mexico or the United States with the infection and has passed it on unwittingly to the two students, or: "There is a chance that institutionwide transmission has been taking place in the university the cases attend or widespread transmission exists in the community in the specific geographical area in Scotland that has led to the exposure of the two cases," the paper said.
Dr Panagiotopoulos wrote: "Cases of the new influenza A (H1N1) infection are for the first time confirmed in travellers from one European country to another, with no specific history of exposure to a traveller from Mexico or the United States and no traceable link to the source of infection.
"It is probably necessary to modify the present EU definition of "cases under investigation" to also include clusters of patients with influenza-like illness, irrespective of travel history."
He pointed out that under the official EU-wide criteria for a suspected case, these students would not have been tested because of the lack of travel history to an affected area and no contact with a confirmed or probable case and this means 'we are by definition going to miss cases infected locally in the event of established community transmission without known and identified chain(s) of transmission'.
A spokesman for the Health Protection Agency said a selection of GPs across the country are taking random swabs from any patient presenting with flu-like illness to check if the disease is more widespread and so far there is no evidence of this.