Economic loss in poultry farms affected with highly pathogenic avian influenza A virus subtype H5N1 and low pathogenic avian influenza A virus subtype H9N2 in Chattogram, Bangladesh

Abstract

Depending on the degree of pathogenicity in chickens, avian influenza virus (AIV) are divided into highly pathogenic (HPAI) or low pathogenic AI (LPAI) viruses. Typically, high morbidity accompanied by high and rapidly escalating unexplained mortality is associated with an HPAI virus. On the other hand, LPAI viruses normally cause only mild or no clinical disease, but under certain circumstances such as with concomitant infection(s) may also cause high mortality. However, published literature seems to be absent in Bangladesh on the economic loss caused by them at the affected farm level. This study was aimed at assessing the economic losses caused by highly pathogenic avian influenza A virus subtype H5N1 (HPAI H5N1) and low pathogenic avian influenza A virus subtype H9N2 (LPAI H9N2) on poultry farms. Cloacal and oropharyngeal samples from chickens supplied from 262 farms between October 2017 and April 2019 were investigated by real-time reverse transcription polymerase chain reaction (rRT-PCR). Of them birds on 16, 15 and 12 farms were diagnosed positive with HPAI H5N1, LPAI H9N2 and with both, respectively. For each of the categories of infection five farms were randomly chosen, and owners or farm representatives were interviewed with a pretested questionnaire to assess the economic losses attributed to them. The results revealed that the farm-level economic loss was variable depending on the number of birds housed on the day of clinical illness and the type of birds (i.e. broiler, layer, and Sonali) reared. On the other hand, the average per-bird loss for broiler, layer, and Sonali chickens due to HPAI H5N1 infection alone was around BDT 26, BDT 182, and BDT 82, respectively. No Sonali farm was diagnosed positive with LPAI H9N2 or HPAI H5N2 plus LPAI H9N2, and therefore, not included in the study. The average per-bird loss attributed to HPAI H5N1 plus LPAI H9N2 was BDT46 in layer and BDT 47 in broiler farm. On the other hand, the average per-bird loss caused by LPAI H9N2 alone was BDT62 in broiler, much higher than the layer in which the estimate was BDT 46.5. To avoid economic loss attributed to HPAI H5N1 and LPAI H9N2 proper biosecurity should be practiced to keep the birds on farms free from the introduction of the viruses.