An outbreak of bird flu in Kazakhstan has been confirmed to be a strain which is potentially deadly for humans. The H5N1 virus has so far killed more than 50 people in Asia since 2003.But Kazakh authorities are playing down the threat of the disease which has so far only affected wildfowl and poultry there. However amid concern the disease will spread, the affected area near the village of Golbovka in the north of the country has been placed under quarantine. The region lies across the Russian border from an area where cases of bird flu have also been reported. It is believed that outbreak should disappear by the end of the month. A new vaccine is currently being tested to prevent humans catching the deadly virus. Nonetheless, some health officials fear the disease could turn into a lethal strain rivalling the Spanish flu that killed up to 40 million people at the end of World War One.