A year after deadly H5N1 bird flu first arrived in Europe, the UK is dealing with its first outbreak on a farm. Yet European efforts to track the virus, let alone defend its poultry, are still in disarray. Later this month, scientists will meet to hammer out a Europe-wide surveillance scheme that will try to work out exactly where the virus is lurking and prevent further outbreaks. The British outbreak, on a large turkey farm in eastern England, follows repeated insistence by British officials that the nation’s wild birds do not have the virus, even though an infected dead swan turned up in Scotland last April. But there is a chance that surveillance is missing the virus.
Thus year’s emergence of H5N1 in western Europe seems to be following a similar pattern to last year. The highly pathogenic virus evolved in poultry in East Asia and crossed Eurasia during 2005. It was then carried to western Europe that autumn by wild birds possibly dabbling ducks, which unlike many birds stay healthy while carrying H5N1. However, there were no visible outbreaks in western Europe until February 2006. Now the same thing is happening this year, with outbreaks of H5N1 in Hungary on 24 January and the UK on 3 February. This suggests H5N1 arrived in the ducks’ wintering grounds in autumn but didn’t immediately strike a visible target. Yet there was no warning of impending flu outbreaks, partly because Europe has no coordinated surveillance for flu in wild birds that would enable researchers to work more closely and share data.
For example, between August 2006 and January 2007 the UK Veterinary Laboratories Agency (VLA) tested 4054 wild British birds, nearly half of them dabbling ducks, but only 15 (0.8 per cent) of the ducks tested positive for any strain of bird flu. In contrast, last autumn Björn Olsen of the University of Kalmar in Sweden, who runs one of Europe’s largest flu surveillance programmes, found ordinary flu in 20 to 40 per cent of ducks using the same migration path as British ducks. Similar findings last year led researchers to query whether the VLA’s sampling technique had let virus degrade through samples drying out (New Scientist, 12 April 2006, p 12). “I would say 0.8 per cent is too low,” says Olsen. “But it is important to harmonise our sampling techniques, or we can’t compare data.”
Later this month, European scientists will meet in Rotterdam, the Netherlands, to launch the NEW-FLUBIRD programme to standardise sampling methodology and determine exactly which birds carry the virus. No sampling so far has detected a healthy bird carrying H5N1. “I’m most concerned that we may be sampling the wrong end of the bird,” says Osterhaus, who now believes H5N1 may be more likely to turn up on a throat swab than in a faecal sample.
February 20, 2007
Original web page at New Scientist