April 11, 2006
Britain’s Bird Flu Testing Method Questioned
LONDON -- Tests done in Britain to determine the extent of avian flu after the H5N1 virus was found in a dead swan may have been flawed, a science magazine said on Tuesday.
Britain's Department of Environment and Rural Affairs (DEFRA) said tests on wild birds were negative for flu which suggests the lethal bird virus was not widespread in the country.
But New Scientist magazine said there could be a problem with how the samples were collected.
"An investigation by New Scientist suggests that all those tests were flawed, meaning no one really knows just how widespread infection among British wild birds might be," the magazine said.
DEFRA defended its methods, saying the most up-to-date testing technologies for avian flu viruses are being used.
"The findings of the DEFRA survey of wild birds are valid," a spokesman said.
Britain reported its first case of the H5N1 strain last week, in a wild bird, when a swan was found dead in Cellardyke harbor in eastern Scotland.
The weekly magazine said its suspicions were raised because samples of droppings from more than 3,000 wild birds taken for DEFRA last December by the conservation group The Wildfowl and Wetlands Trust (WWT) showed only 0.06 percent had the ordinary flu that ducks and geese normally carry.
Ruth Crommie of the WWT told the magazine that the group thought the low figures occur in some bird populations.
But experts contacted by the magazine said normally about 10 percent of ducks and 1 percent of geese have signs of ordinary avian flu in Europe in December.
"The problem may have been DEFRA's method of collecting samples," according to the magazine.
Crommie said DEFRA told the WWT samplers to take fecal samples on a sterile moistened swab and to put them in dry plastic tubes before freezing. But the independent experts said the samples would need to be immersed in a saline or preservative solution before being frozen.
"If you left a swab in the refrigerator in its sheath like that, it could dry out and your would lose all your virus," said Bjorn Olsen, of the University of Kalmar in Sweden, who tests 10,000 birds each year for avian flu.
But the DEFRA spokesman added: "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 Influenza A viruses in wild birds in the UK."
Scientists fear H5N1 could mutate into a strain that could become highly infectious in humans, capable of causing a pandemic that could kill millions of people. So far the virus has not shown it can be spread easily from person to person.