Published online by Cambridge University Press: 27 August 2010
Bangladesh first experienced highly pathogenic avian influenza (HPAI) in early 2007 and the National Reference Laboratory for Avian Influenza (NRL-AI) at BLRI diagnosed and confirmed the presence of H5 sub-type virus on 15 March 2007. Until May 2009, NRL-AI observed 323 H5 and three H9 positive cases. Gene sequencing of 25 isolates of 2007 and 2008 demonstrated 99.1 to 100% identical genetic structure, indicating a single introduction of the virus in Bangladesh. It also clearly demonstrated that Bangladeshi isolates belong to the sub-clade 2.2 popularly known as Qinghai lineage or Euro-Asian-African lineage with highest similarities to those from Kuwait, Mongolia, Russia and Afghanistan. The close similarities between the HPAI isolates of these countries with Bangladeshi isolates suggest that migratory birds might be responsible for initial introduction of HPAI in Bangladesh as the country has no poultry trade link with these countries. Identifying possible risk factors in the spread of HPAI in the country was examined through descriptive as well as case control studies. It was revealed that, in most cases, mortality in backyard chicken flocks preceded an outbreak on commercial farms. Poor management and breaches in biosecurity practices appeared to have significant role in the spread of HPAI. The poultry industry in Bangladesh faced a terrific financial loss in 2007 and 2008 due to the incursion of avian influenza, which was estimated to be at Taka 3858 crore (38580 million). The prices of broiler declined by about 28% while the price of eggs decreased by 26.5%, as more than one third of consumers refrained from consumption of broiler meat and eggs. As a result of this market collapse, many farm owners were compelled to abandon poultry production because of loss of capital.