Khairhani Municipality in Chitwan district has reported an outbreak of H5N1 bird flu, authorities said. The virus has killed 2,500 hens exposed in two poultry farms while the remaining domestic birds including ducks, hens and pigeons were culled by the city authorities. According to Chief of National Avian Disease Investigation Laboratory, Dr Daya Ram Chapagain, the virus was detected after few samples of dead hens from poultry farms owned by Rajan Chaudhary and Laxman Chaudhary were brought to the laboratory. In response to the outbreak of severe avian influenza, a cabinet meeting on Thursday took the decision to slaughter domestic birds in the surrounding areas, Dr Chapagain said. Likewise, few areas of the municipality were declared contaminated with a ban on hauling birds, to and from, the contaminated areas in effect. Prior to this, the H5N1 avian influenza was reported in the district five years ago. The World Health Organisation has asserted that H5N1 is a type of influenza virus that causes a highly infectious, severe respiratory disease in birds. "Human cases of H5N1 avian influenza occur occasionally, but it is difficult to transmit the infection from person to person. When people do become infected, the mortality rate is about 60 per cent," WHO says.