EU countries broadening H1N1 flu tests: officials

A worker puts on a face mask inside a sterile zone at a hospital equipment factory in Cornella, near Barcelona, April 30, 2009.

LONDON (Reuters) - European Union countries have begun casting a wider net when deciding who to test for the new H1N1 flu virus as health authorities are concerned they may have been missing cases, officials said.

Flu experts began emergency talks on Friday to discuss the spread of the H1N1 virus and introducing a severity index into the World Health Organisation's top level of pandemic alert.

The effects of the new flu have been mainly mild apart from in Mexico, where it is known to have killed 103 people.

Testing strategies for the most part had relied on looking for cases of the so-called swine flu among travelers returning from affected countries and their close contacts, European and British health officials said.

But that could mean some people may not have been tested for the new virus even if they showed symptoms.

Britain's Health Protection Agency has changed its rules to recommend testing any patient with flu symptoms, while an expert at the European Centres for Disease Control and Prevention said more countries are broadening the scope of testing.

"In any case-finding mode, one looks for cases where they are most likely to appear -- and all throughout May this has been in travelers and their contacts," Johan Giesecke, the ECDC's chief scientist, said by e-mail.

"But more and more EU member states are now casting 'wider nets.'"

The new strain, commonly known as swine flu, has infected 21,940 people in 69 countries, killing 125 of them, according to the WHO. Mexico, the United States and Canada have borne the brunt of the illness. Work continues on developing a vaccine.

To declare a full pandemic the WHO would have to confirm sustained spread of the virus in one country in another region besides the Americas.

While there have been hundreds of cases across Europe, officials stress there are still no signs of sustained transmission within communities and the focus remains on delaying the spread of infection.

"It is also important to point out that of the total cases reported (in the region) almost half are now reported as in-country transmission," Giesecke said.

"However, an epidemiological link to an already known case can be established for the majority of the cases. Sustained community transmission is still to be detected."

Britain is one country that has tweaked how it defines potential cases, a decision that now gives health officials wider latitude to test people with suspected infections.

A Health Protection Agency spokesman said officials have seen a small number of sporadic cases in individuals who have had no travel history to countries affected by the flu and no links to existing cases.

(Additional reporting by Laura MacInnis, Stephanie Nebehay in Geneva; Editing by Maggie Fox and Jon Hemming)