A Decade of Avian Influenza in Bangladesh: Where Are We Now?

Abstract

Highly pathogenic avian influenza (HPAI) has been a public health threat in Bangladesh since the first reported outbreak in poultry in 2007. The country has undertaken numerous efforts to detect, track, and combat avian influenza viruses (AIVs). The predominant genotype of the H5N1 viruses is clade 2.3.2.1a. The persistent changing of clades of the circulating H5N1 strains suggests probable mutations that might have been occurring over time. Surveillance has provided evidence that the virus has persistently prevailed in all sectors and caused discontinuous infections. The presence of AIV in live bird markets has been detected persistently. Weak biosecurity in the poultry sector is linked with resource limitation, low risk perception, and short-term sporadic interventions. Controlling avian influenza necessitates a concerted multi-sector ‘One Health’ approach that includes the government and key stakeholders.

Factors influencing the epidemiology of avian influenza virus circulation on poultry farms in Bangladesh

“…could potentially increase the uptake of AI vaccinations (DhakaHerald, 2013; DLS, 2013; Rimi et al, 2019).…”

“…Upazillas or sub-districts (out of 490 Upazillas) of Bangladesh across 52 districts (out of 64 districts) resulting in the culling and destruction of more than 2.87 million birds (and 3.7 million eggs) (DLS, 2019). Since 2013, the reporting of HPAI H5N1 outbreaks has declined, but HPAI H5N1 is still being isolated regularly from live bird markets in Bangladesh (Marinova-Petkova et al, 2016;Rimi et al, 2019;Turner et al, 2017). In addition to the significant economic impact of HPAI on the poultry production in Bangladesh (DLS 2019;FAO, 2014), the country has also experienced eight HPAI H5N1 human cases with one fatality as of September 2019 (WHO, 2019).…”

“…Since 2014, the Government of Bangladesh has permitted the use of these three vaccines throughout the country (Rimi et al, 2019). However, a study conducted by Ansari et al (2016) in Bangladesh reported vaccination failures and poor immune responses in layer chickens on H5 vaccinated farms, though the authors did not mention the type of H5 vaccines used to vaccinate the sampled layer chickens.…”

“…The implementation of comprehensive biosecurity practices is notoriously challenging, if at all feasible, in a backyard farming system (Rimi et al, 2019). The lack of adherence to recommended biosecurity practices is likely influenced by backyard farmers' belief that their poultry does not play a significant role in AIV transmission (Bavinck et al, 2009).…”

“…The decline of reported H5N1 outbreaks in poultry since 2013 and only one human fatality since the emergence of HPAI are the main reasons why the development and implemenation of HPAI policies are not considered as a priority in Bangladesh (Rimi et al, 2019). On the other hand, farm and LBM investigations in Bangladesh confirmed that H5N1 and H9N2 virus subtypes are widely circulatig in commercial broiler and layer flocks (Ansari et al, 2016;Kim et al, 2018), although fewer outbreaks and less severe clincal signs in birds are reported by farmers.…”