North Korean bird flu outbreak not the feared strain

时间:2019-03-02 09:03:00166网络整理admin

By Debora MacKenzie An outbreak of bird flu on three large poultry farms in North Korea has been tentatively identified as the H7 strain of the virus – not the H5N1 strain that has been killing people and poultry across east Asia for more than a year. But UN officials have revealed to New Scientist that the evidence for this is only indirect. South Korea reported in March that its secretive northern neighbour had suffered bird flu outbreaks near the capital, Pyongyang, since early February 2005. Concern immediately flared that it was H5N1, which has killed at least 49 people across East Asia to date. North Korea is extremely poor, with persistent food shortages and much of the population prone to disease. It is also slow to accept visits or help from outsiders, a combination that could allow an H5N1 outbreak to run out of control, possibly triggering a human pandemic. North Korean authorities finally confirmed they had bird flu outbreaks last week, saying more than 200,000 birds had been destroyed on three large farms near Pyongyang. Hans Wagner of the UN Food and Agricultural Organization (FAO) announced on Tuesday – after a week-long visit to the country – that the virus responsible is the H7 strain of avian influenza. But Juan Lubroth, head of infectious diseases at the FAO, told New Scientist that the evidence is indirect. “The North Koreans made a vaccine using virus from the sick chickens, and vaccinated chickens in the region around the outbreak,” he says. “Those chickens show a high level of antibodies to H7.” So it appears the outbreak was H7 flu. But this is a mystery, as an outbreak of H7 has never been recorded in east Asia before. “The North Koreans say they have destroyed all the sick chickens, and the outbreak is now over,” says Lubroth. “That’s good for the Koreans. But we’d like a sample of tissue from the infected birds so we can isolate the virus.” A genetic sequence might help trace the strain’s origins, and whether it has mixed with other Asian strains. H7 flu caused outbreaks in poultry in 2004 in the US, Canada, Pakistan and the Netherlands, where it also infected 245 Dutch chicken workers and their contacts. Most had no symptoms, but one vet died. Meanwhile, 11 new human cases of H5N1 have been confirmed in Vietnam in the past month, bringing the total number since the current outbreak began in December 2004 to 33, of whom 15 have so far died. A second case in Cambodia, who died, was also confirmed last week. Klaus Stõhr, head of flu at the World Health Organization in Geneva, is calling for countries to set aside 5% of what they normally spend on flu vaccination for research into vaccines against a flu pandemic. But only rich countries spend much on normal flu vaccination, and only about a quarter of the world’s vaccine was used outside the US, Canada, Western Europe, Japan and Australia in 2003,