Molecular epidemiology and pathogenicity of H5N1 and H9N2 avian influenza viruses in clinically affected chickens on farms in Bangladesh

Avian influenza virus subtype H9N2 is endemic in Bangladesh’s poultry population. The subtype affects poultry production and poses a potential zoonotic risk. Insufficient understanding of how the poultry trading network shapes the dissemination of avian influenza viruses has hindered the design of targeted interventions to reduce their spread. Here, we use phylodynamic analyses of haemagglutinin (HA) sequences to investigate the spatial spread and dispersal patterns of H9N2 viruses in Bangladesh’s poultry population, focusing on its two largest cities (Dhaka and Chattogram) and their poultry production and distribution networks. Our analyses suggest that H9N2 subtype avian influenza virus lineage movement occurs relatively less frequently between Bangladesh’s two largest cities than within each city. H9N2 viruses detected in single markets are often more closely related to viruses from other markets in the same city than to each other, consistent with close epidemiological connectivity between markets. Our analyses also suggest that H9N2 viruses may spread more frequently between chickens of the three most commonly sold types (sunali - a cross-bred of Fayoumi hen and Rhode Island Red cock, deshi - local indigenous, and exotic broiler) in Dhaka than in Chattogram. Overall, this study improves our understanding of how Bangladesh’s poultry trading system impacts avian influenza virus spread and should contribute to the design of tailored surveillance that accommodates local heterogeneity in virus dispersal patterns.

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“…2016 ; Rimi et al 2019 ) and is known to cause reduced egg-laying and hatching ( Kariithi et al. 2020 ; Ripa et al. 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…( Gerloff et al. 2016 ; Ripa et al. 2021 )) or have not incorporated information on the precise sampling location or type of chicken (e.g.…”

Section: Introductionmentioning

confidence: 99%

H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks

et al. 2023

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“…Currently, several East Asian countries (Bangladesh, China, Indonesia, and Viet Nam), as well as Egypt, are considered to be endemic for HPAI viruses [30,31]. The problem is exacerbated when various subtypes of HPAI and LPAI viruses cocirculate in different species of birds [32][33][34][35][36][37][38]. Domestic ducks appear to serve as intermediary mixing vessels for several subtypes of influenza viruses following acquisition from migratory water birds [39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Semi-Scavenging Poultry as Carriers of Avian Influenza Genes

Atm

Rahman

Hasan

et al. 2022

Life

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Ducks are the natural reservoir of influenza A virus and the central host for the avian influenza virus (AIV) subtype H5N1, which is highly pathogenic. Semi-scavenging domestic ducks allow for the reemergence of new influenza subtypes which could be transmitted to humans. We collected 844 cloacal swabs from semi-scavenging ducks inhabiting seven migratory bird sanctuaries of Bangladesh for the molecular detection of avian influenza genes. We detected the matrix gene (M gene) using real-time RT–PCR (RT–qPCR). Subtyping of the AIV-positive samples was performed by RT–qPCR specific for H5, H7, and H9 genes. Out of 844 samples, 21 (2.488%) were positive for AIV. Subtyping of AIV positive samples (n = 21) revealed that nine samples (42.85%) were positive for the H9 subtype, five (23.80%) were positive for H5, and seven (33.33%) were negative for the three genes (H5, H7, and H9). We detected the same genes after propagating the virus in embryonated chicken eggs from positive samples. Semi-scavenging ducks could act as carriers of pathogenic AIV, including the less pathogenic H9 subtype. This can enhance the pathogenicity of the virus in ducks by reassortment. The large dataset presented in our study from seven areas should trigger further studies on AIV prevalence and ecology.

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“…However, studies conducted in farms and live bird markets (LBMs) have shown that H5N1 and H9N2 virus subtypes circulate in Bangladeshi poultry ( 16 , 17 ), with the low number of outbreaks being likely due to underreporting by farmers ( 12 , 15 ). A recent study conducted on clinically affected or dead chickens with suspected AIV infection on 262 farms in Bangladesh, reported a prevalence of 4.4 and 10.1% across broiler, and 25.6 and 14.1% across layer farms, for H5 and H9 AIV subtypes, respectively ( 18 ). Interestingly, research in apparently healthy broilers and layers in Bangladesh did not detect the H5 AIV subtype, but 1.9 and 2% of the broiler and layer farms were H9 AIV positive, respectively ( 19 ).…”

Section: Introductionmentioning

confidence: 99%

Farm-Level Risk Factors Associated With Avian Influenza A (H5) and A (H9) Flock-Level Seroprevalence on Commercial Broiler and Layer Chicken Farms in Bangladesh

et al. 2022

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A cross-sectional study was conducted to identify farm-level risk factors associated with avian influenza A H5 and H9 virus exposure on commercial chicken farms in Bangladesh. For broiler farms, both H5 and H9 seropositivity were associated with visits by workers from other commercial chicken farms [odds ratio (OR) for H5 = 15.1, 95% confidence interval (CI): 2.8–80.8; OR for H9 = 50.1, 95% CI: 4.5–552.7], H5 seropositivity was associated with access of backyard ducks (OR = 21.5, 95% CI: 2.3–201.1), and H9 seropositivity with a number of farm employees (OR = 9.4, 95% CI: 1.1–80.6). On layer farms, both H5 and H9 seropositivity were associated with presence of stray dogs (OR for H5 = 3.1, 95% CI: 1.1–9.1; OR for H9 = 4.0, 95% CI: 1.1–15.3), H5 seropositivity with hatcheries supplying chicks (OR = 0.0, 95% CI: 0.0–0.3), vehicles entering farms (OR = 5.8, 95% CI: 1.5–22.4), number of farm employees (OR = 5.8, 95% CI: 1.2–28.2), and burying of dead birds near farms (OR = 4.6, 95% CI: 1.2–17.3); H9 seropositivity with traders supplying feed (OR = 5.9, 95% CI: 1.0–33.9), visits conducted of other commercial poultry farms (OR = 4.7, 95% CI: 1.1–20.6), number of spent layers sold (OR = 24.0, 95% CI: 3.7–155.0), and frequency of replacing chicken droppings (OR = 28.3, 95% CI: 2.8–284.2). Policies addressing these risk factors will increase the effectiveness of prevention and control strategies reducing the risk of avian influenza on commercial chicken farms.

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Molecular epidemiology and pathogenicity of H5N1 and H9N2 avian influenza viruses in clinically affected chickens on farms in Bangladesh

Cited by 17 publications

References 62 publications

H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks

H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks

Semi-Scavenging Poultry as Carriers of Avian Influenza Genes

Farm-Level Risk Factors Associated With Avian Influenza A (H5) and A (H9) Flock-Level Seroprevalence on Commercial Broiler and Layer Chicken Farms in Bangladesh

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