Bangladesh\'s authorities have culled nearly 14,000 chickens and destroyed about 50,000 eggs since this season\'s first outbreak of bird flu was detected last month, an official said Tuesday. The government\'s bird flu control room official told Xinhua that \"some 13,727 chickens were culled since its resurrection last month.\" Fresh outbreak of bird flu was detected in Bangladesh in the second week of November with arrival of winter season. Ataur Rahman, assistant director at the control room of Fisheries and Live Stock Department, said some 12,762 chickens were culled in two commercial farms in central Manikganj and western Rajbarbi districts. He said some 965 birds, including 400 at the latest on Monday, were culled in two flu-hit farms so far this month. \"A total of 44, 756 eggs were also destroyed since the first outbreak in mid November,\" he added. The country\'s Fisheries and Live Stock Department has strengthened its surveillance to contain further spread of the infectious disease -- H5N1, said Rahaman. He said the department had instructed its officials to motivate farmers to adopt all required preventive measures since the disease was found to reemerge last month. So far, the disease has spread to four districts of the South Asian country since its resurrection last month. There is also instruction for field-level officials for proper culling, destruction, disposal and decontamination immediately after diagnosis. With the fall in temperature in January and February, risky factors of bird flu disease will continue to rise in Bangladesh, said another official who asked to be unnamed. \"Although we don\'t expect that there will be a massive outbreak of avian flu this time but we can\'t rule out the possibility of major resurrection of the disease in the dangerous winter season, which is the high time for outbreak of the disease,\" he said. The official added the fresh detections indicate that the virus is still active and may spread to other parts of the country. Bangladesh\'s poultry farmers also suffered from the outbreak of the disease during winter season in 2009 and 2010. The bird flu was first detected in Bangladesh in a poultry farm near capital Dhaka in March 2007. The situation deteriorated later on as the virus spread fast across the country and was reported in 47 districts between December 2007 and March 2008. The first bird flu in human body in Bangladesh was detected on May 21, 2008. The Center for Disease Control and Prevention in the United States diagnosed a 16-month-old Bangladesh child as being infected with H5N1 who later recovered.