New swine flu cases point to invisible pandemic

13:17 29 May 2009 by Debora MacKenzie

Hospitals in Greece have identified H1N1 swine flu in two students who had no contact with known cases of the virus and had not been in countries with widespread infection. The infections were discovered even though the students should not have been tested for swine flu under European rules. The Greek authorities say this shows the rules must change.

Indeed, an investigation by New Scientist earlier this month showed that the EU rules would exclude exactly such cases and could make H1N1 appear much less widespread in Europe than it is.

Takis Panagiotopoulos of the Hellenic Centre for Disease Control and Prevention in Athens and colleagues reported on 28 May in Eurosurveillance, a weekly bulletin published by the European Centre for Disease Prevention and Control (ECDC) in Stockholm, Sweden, that two Greek men returning home from Scotland had tested positive this week for H1N1 swine flu.

Chance test

The two go to university in Edinburgh and had attended term-end parties at the end of last week. Both developed coughs and fevers at the weekend before flying back to Greece, where one went to hospital in Athens on Tuesday.

"The examining physician decided to take a pharyngeal swab, which was tested at the National Influenza Reference Laboratory for Southern Greece, although the patient did not meet the European Union and national criteria for the new influenza A (H1N1) testing," the team reports.

The swab was tested with a kit for H1N1 distributed by the US Centers for Disease Control and Prevention (CDC), and was positive for swine flu. The student in Athens warned the second student, who was now in Thesaloniki. He also tested positive. Both cases were mild.

Contacts of the two in Greece and Scotland and on the flights are being traced.

'Missing cases'

The Greek cases are "community acquired", meaning they have no contacts with known cases or countries with swine flu. The ECDC guidelines adopted by most EU countries, including Greece, recommend testing for H1N1 only when people have such contacts, excluding community acquired cases.

"It is of concern that with the present EU [testing criteria] we are by definition going to miss cases infected locally in the event of established community transmission," the Greek team warns. "It is probably necessary to modify the present EU definition … to also include clusters of patients with influenza-like illness, irrespective of travel history," they say, especially as the tourist season is getting under way.

Officially, swine flu has increased very slowly in Britain, even though the virus appears to be as contagious as ordinary flu. John Oxford of the University of London says the UK may have tens of thousands of mild, untested cases. The US CDC says there could be 100,000 cases in the US, even though only a few thousand, mostly severe, cases have been tested.

Finding community acquired cases outside the Americas is a requirement for declaring H1N1 swine flu an official pandemic, which the WHO has not yet done.