The One Health Epidemiology of Avian Influenza Infection in Bangladesh: Lessons Learned from the Past 15 Years

Abstract

Avian influenza viruses (AIVs) are significant transboundary zoonotic pathogens that concern both animal and human. Since the first report of H5N1 AIV in Bangladesh in early 2007, it resulted in numerous outbreaks across the country, hindering the sustainable growth of the poultry industry through economic losses in different production systems (commercial and backyard). Highly pathogenic avian influenza (HPAI) virus and low pathogenic avian influenza (LPAI) virus are currently cocirculating and causing infection in poultry sectors in an endemic manner in Bangladesh as well as in wild bird species. The introduction of multiple clades of H5N1 in different poultry species and the reassortment of AIVs with different patterns of infections have complicated the epidemiological situation for control and created conditions to increase the virulence of the virus, host range, and potential zoonotic transmission. The risk of viral transmission at the human-poultry interface is increasing over time due to inadequate surveillance and early detection strategies and practices, ineffective biosecurity practices among poultry raisers, and the complex supply chains of backyard and commercial poultry and live bird market (LBM) systems. Improving AIV surveillance in poultry flocks and LBMs, vaccination, biosecurity, and awareness among poultry professionals is beneficial to controlling the disease burden in the poultry sector. However, human cases of AIV related to poultry production and marketing chain in Bangladesh suggest a One Health approach engaging various stakeholders from the public and private would be a better option for successfully controlling avian influenza outbreaks in Bangladesh. This review of literature presents the comprehensive overview of AIV infection status in Bangladesh, including a description of pathways for zoonotic transmission at different epidemiological interfaces, the genetic evolution of the virus, and the need for improvement of disease control strategies incorporated with early detection, application of effective vaccines, increases the proper biosecurity practices and improvement of awareness among the poultry raisers, traders and consumers using a One Health approach.

Figure 1

The distribution of HPAIV H5N1 outbreak in poultry reported districts in Bangladesh. The map shows the district boundaries of Bangladesh, where indicates the districts with reported HPAI H5N1 outbreaks in poultry and country's waterbodies.

Figure 2

Transmission dynamics of avian influenza virus in the different poultry production systems of Bangladesh. (a) Shows four different poultry farm settings, which also shows poor biosecurity management in the farms. The virus can move from commercial farms to backyard poultry farms or vice versa by stray dogs, cats, resident birds, and human workers (b). The virus can spread through the live poultry and egg transportation system (c), resident wild animals, such as foxes, mink, ferrets, rodents, and monitor lizards (Guishap) (d) and farm tools (e) [55].

Figure 3

Transmission dynamics of avian influenza virus in the live bird marketing system of Bangladesh. The central figure (a) shows the open live bird marketing systems in Bangladesh, either by small shops or street marketing. The virus can spread through (b) the resident birds such as crow, sparrow, magpie, starling, bulbul, and eagle; (c) egg and live bird transportation systems; (d) stray animals, such as dogs, cats, and commensal rodents; and (e) mobile poultry vendor in the urban area [55].

Figure 4

Transmission dynamics of avian influenza virus in the wetland ecosystem of Bangladesh. The virus is imported to Bangladesh wetlands by the migratory bird (a). Then the virus can spread throughout Bangladesh by the resident wild birds, such as the cormorant, heron, water hen, egal, kingfisher, and wild duck (b); range ducks (c), resident wild animals (d), and domestic ducks in the backyard poultry farming system (e) [55].