|
Fear bird flu test 'flaws' have missed other
cases
GETHIN CHAMBERLAIN
CHIEF NEWS CORRESPONDENT
SCIENTISTS have raised the possibility that hundreds
of cases of bird flu may have been missed because
of flaws in Britain's testing regime.
Dr Bjorn Olsen, who conducts Europe's biggest
bird monitoring survey, warned yesterday that
many flu cases could be missed because of the
way that samples are handled.
His concerns about the methods used were backed
yesterday by Professor Hugh Pennington, Britain's
leading bacteriologist, who said the criticism
appeared to be valid.
The claims came as the authorities continued
to deliberate on the need for further measures
to be put in place in the wake of the discovery
that the swan found in Fife with the H5N1 strain
of bird flu was a migratory bird which may have
moved around the UK infecting other populations.
Writing in the New Scientist magazine Dr Olsen,
from the University of Kalmar in Sweden, questioned
the comparatively low rates of positive tests
for cases of low pathogenicity bird flu found
by the Department for Environment, Food and Rural
Affairs (DEFRA).
During tests in December, DEFRA found only two
cases of low-pathogenic bird flu out of 3,343
samples collected by the Wildfowl and Wetlands
Trust - equivalent to 0.06 per cent. Another study
found that in 423 ducks, only 0.7 per cent had
bird flu.
But Dr Olsen said the UK findings were flawed.
"There's something wrong with these numbers,"
he said.
Dr Olsen tests 10,000 birds a year and typically
finds that 10 per cent of dabbling ducks and 1
per cent of geese are infected with low-pathogenic
bird flu. Other studies carried out with colleagues
in Holland have found even higher infection rates.
In the US, experience indicates that 6 to 7 per
cent of birds should test positive for mild forms
of flu.
Dr Olsen said the method of sample collection
may be the behind the discrepancy.
His concerns were echoed by Prof Pennington,
from the University of Aberdeen. He said: "The
virus is not that stable. As soon as the bird
dies, the virus starts to die. You can reduce
the death rate by keeping it under appropriate
controls in an appropriate medium. You can protect
the virus by putting it in an appropriate liquid.
There are genuine issues here about whether DEFRA
is using the right system or not."
DEFRA said it stood by its testing methods and
said that the Veterinary Laboratories Agency,
which carries out the tests, was world renowned.
|
