British, Hungarian bird flu outbreaks linked

LONDON (Reuters) - Tests on H5N1 bird flu viruses found in Britain and Hungary showed they were genetically almost identical and the most likely transmission route was from poultry to poultry, Britain said on Tuesday.

The establishment by scientists in Britain of a direct link between the two outbreaks came the same day Hungary said it had found no evidence poultry there could have transmitted the virus to Britain.

The two countries have been feuding over the likely source of the British contamination, which led to the destruction of tens of thousands of turkeys in Britain. Hungarian officials disputed British statements earlier this week that the virus probably came from turkey meat imports, rather than wild birds.

But scientist John McCauley of the virology division of the Medical Research Council's Institute for Medical Research supported the British contention.

"It seems very unlikely that a strain of infection in wild birds could have produced two viruses so closely related," he said.

Britain stressed that while the outbreaks were linked it had not found any evidence of illegal or unsafe movements of poultry products from Hungary to Britain and was still investigating all possible routes of transmission.

Asked whether this suggested that biosecurity measures might have been inadequate, a spokeswoman for Britain's Department for Environment, Food and Rural Affairs (DEFRA) said they were not prejudging the full results of the investigation.

A case of H5N1 was discovered in geese in southeast Hungary last month. The tests at Britain's Veterinary Laboratory Agency aimed to establish whether there was a direct link to a similar outbreak this month at a turkey farm in Suffolk, England.

DEFRA said the final results showed a very high similarity (99.96 pct) at the whole genome level.

"These results indicate that the viruses are essentially identical," it said in a statement.

"These levels of identity are much closer than with other Asian lineage H5 viruses for which data is available, including those isolated from wild birds in Europe in 2005/06," the VLA's chief avian virologist Ian Brown said.

Britain's deputy chief veterinarian Fred Landeg said the working hypothesis, based on the work of the VLA, was that the virus had most likely been transmitted from poultry to poultry.

"I must reiterate that we are not discounting any line of inquiry and this is an on-going investigation," he said.

The EU commission also said that while the tests showed the outbreaks were directly linked, that in itself did not explain how the strain came to Britain.

"We are not going to speculate, nor should anybody, as to how it arrived as this is still part of an ongoing investigation. But we reiterate our view that the Hungarian authorities have acted properly and took the right measures," said Philip Tod, spokesman for EU Health Commissioner Markos Kyprianou.

Europe's largest turkey producer, Bernard Matthews, reopened the plant hit by the outbreak earlier this month on Tuesday after 160,000 turkeys at a nearby farm were destroyed.

(Additional reporting by Jeremy Lovell in London, Darren Ennis in Brussels, Andras Gergely and Gergely Szakacs in Budapest)