The response from the Department for Environment, Food and Rural Affairs (Defra) was in reaction to a report in New Scientist magazine. The magazine quoted experts as questioning whether the low rates of milder forms of the disease found in the UK's wild birds indicated flawed testing methods.
"The findings of the Defra survey of wild birds are valid," a Defra spokesperson told FoodProductionDaily.com today. "Simply because previous surveys have revealed different results does not invalidate the present survey, which should be regarded as the most up-to-date source of data on the prevalence of avian influenza viruses in wild birds in the UK."
Since the beginning of the avian flu crisis in Europe, consumption of poultry and eggs has fallen dramatically in some member states, leading to a sharp reduction in prices.The questions raised over the UK's testing methods could give the public further cause for concern.
Last week, UK scientists found the deadly H5N1 form of bird flu for the first time in the country. A dead swan in Fife, Scotland tested positive for the highly pathogenic form of the disease, which may be transmitted to poultry flocks and to humans.
On 6 April Defra again stated that other tests on wild birds so far were negative for flu, so the H5N1 virus was unlikely to be widespread . The regulator stood by its policy that there was no need to require that all UK poultry be kept indoors as a precaution against the disease.
"We are urgently considering whether there is a need for any regional measures in addition to those that have already been put in place in the protection and surveillance zones," according to a joint statement from the chief veterinary officers in the UK and Scotland. "Further advice will be available once the full veterinary assessment is complete and this situation will be reviewed on a daily basis."
However New Scientist yesterday quoted Bjorn Olsen, who conducts Europe's largest bird monitoring survey, as warning that regulators may have missed many flu cases because of the way that samples are handled.
Olsen, a scientist at Sweden's University of Kalmar, said the comparatively low rates of positive tests for cases of low pathogenicity bird flu found by Defra.
He said Defra's tests revealed none of the ordinary flu that ducks and geese normally carry. Of the 3,343 faecal samples from wild birds taken for Defra by the conservation group the Wildfowl and Wetlands Trust (WWT) in December, only two were shown to contain low-pathogenicity bird flu, or about 0.06 per cent.
In a parallel study for Defra conducted by hunters, bird flu was found in only three of 423 freshly shot ducks, or 0.7 per cent, according to New Scientist.
Olsen was quoted as stating that about 10 per cent for dabbling ducks and one per cent of geese should be carrying low-pathogenicity bird flu in Europe in December.
Other scientists from the US told New Scientist that "at least 6 or 7 per cent should be positive" at any time.
"We thought there was an unusually low level but perhaps that happens in some bird populations," Ruth Crommie of the WWT was quoted as stating in the magazine.
The Defra spokesperson said the UK's Veterinary Laboratories Agency (VLA) is using the most up-to-date testing technologies to detect avian influenza viruses.
"The VLA is world renowned for its avian influenza testing work," he said. "As an international reference laboratory for avian influenza, the VLA even verifies other countries' test results It is internationally recognised as a centre of excellence in veterinary research."
The march of avian influenza across Europe has heightened the public's fears over the safety of the bloc's poultry. Poultry consumption has plunged in many EU member states, by up to 70 per cent in some countries.
Scientists are worried that the H5N1 form of the virus, which can be transmitted from poultry to humans, may mutate so that it can be transmitted from human to human and start a influenza pandemic.
About 100 people have died from the disease so far worldwide, including four in Turkey and three in Azerbaijan.
The UN Food and Agriculture Organisation (FAO) reported that recent avian influenza outbreaks in Europe, the Middle East and Africa have caused dramatic swings in poultry consumption, increased trade bans and sharp price declines. The UN agency expects poultry consumption shocks this year in many countries.