Some 531 chickens were culled at a poultry farm in Gazipur on Monday in presence of the district livestock officer after it was affected by bird flu virus H5N1. The Field Disease Investigation Laboratory at Jaypurhat on Sunday confirmed that the virus affected Lata Poultry farm at Khetlal Upazila. Earlier this month, Yati Poultry Farm in the same upazila was affected with the virus. The district livestock authorities culled some 932 chickens and 183 eggs to contain the spread of the virus within 12 hours of confirmation. Talking to The Daily Star, Jaypurhat District Livestock Officer Dr Shahidul Islam said the newly affected farm was less than half a kilometre away from the previous one where H1N1 virus was confirmed on January 5. "The virus broke out due to lack of bio-security maintenance. Both the farms are situated adjacent to the dwelling place and people are coming in contact with the farms frequently," he said. The last outbreak was experienced in the country in August 2009 in Bogra. But it was not a massive one, said sources at the Institute of Epidemiology, Disease Control and Research (IEDCR). Bird flu killed at least 287 people affecting 467 worldwide since it began to ravage poultry stocks in Asia in late 2003. World Health Organisation has counted the fatality at more than 60 percent.