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Source: https://www.nature.com/articles/s41467-024-47703-9
Open access
Published: 01 May 2024
Modelling the transmission dynamics of H9N2 avian influenza viruses in a live bird market
Francesco Pinotti, Lisa Kohnle, José Lourenço, Sunetra Gupta, Md. Ahasanul Hoque, Rashed Mahmud, Paritosh Biswas, Dirk Pfeiffer & Guillaume Fournié
Nature Communications volume 15, Article number: 3494 (2024) Cite this article
Abstract
H9N2 avian influenza viruses (AIVs) are a major concern for the poultry sector and human health in countries where this subtype is endemic. By fitting a model simulating H9N2 AIV transmission to data from a field experiment, we characterise the epidemiology of the virus in a live bird market in Bangladesh. Many supplied birds arrive already exposed to H9N2 AIVs, resulting in many broiler chickens entering the market as infected, and many indigenous backyard chickens entering with pre-existing immunity. Most susceptible chickens become infected within one day spent at the market, owing to high levels of viral transmission within market and short latent periods, as brief as 5.3 hours. Although H9N2 AIV transmission can be substantially reduced under moderate levels of cleaning and disinfection, effective risk mitigation also requires a range of additional interventions targeting markets and other nodes along the poultry production and distribution network.
Introduction
H9N2 Avian influenza virus (AIV) is considered to be the most prevalent AIV in poultry globally1. Despite being classified as a low pathogenic virus, H9N2 AIV is responsible for substantial economic loss for the poultry industry2,3. Infection is typically associated with moderate to severe respiratory symptoms, delayed growth, reduced egg production and increased mortality, especially when co-infection with other pathogens is involved4. Some H9N2 AIV lineages are known to be zoonotic, with resulting symptoms being typically mild. Co-circulation with other AIV subtypes may lead to the emergence of reassortant viruses with increased pathogenicity and/or zoonotic potential5,6,7. H9N2 appears to be involved in the origin of several novel zoonotic AIVs, whose number has been rapidly increasing since 20138. AIVs with H9N2-derived genes include H7N99, H5N1, H10N810,11,12 and, more recently, H3N813.
In many Asian countries, the prevalence of H9N2 AIVs is particularly high in live bird markets (LBMs), with estimates in Bangladeshi markets as high as 80%14,15. LBMs play a central role in the marketing of poultry in developing countries, being the place of choice for many people to purchase meat for consumption. At the same time, the high prevalence of AIV infection among traded poultry is concerning due to the risk of zoonotic spillover to humans5,16,17. In LBMs, the latter may be exposed to AIV through contaminated dust particles, water, surfaces and the slaughtering of infected birds. LBMs are also known to promote the mixing and evolution of AIVs, in that they enable the intermingling of multiple poultry species from many distant locations and diverse farming systems18,19,20. Over the last 25 years, public health concerns around LBMs have prompted health authorities in several Asian countries to take steps to control AIV transmission in these settings; adopted measures included enhanced hygiene protocols, bans on overnight poultry storage, as well as periodic rest days21,22,23,24,25,26. Temporary and permanent market shutdowns have also been employed in response to outbreaks of emerging zoonotic AIVs27...
Open access
Published: 01 May 2024
Modelling the transmission dynamics of H9N2 avian influenza viruses in a live bird market
Francesco Pinotti, Lisa Kohnle, José Lourenço, Sunetra Gupta, Md. Ahasanul Hoque, Rashed Mahmud, Paritosh Biswas, Dirk Pfeiffer & Guillaume Fournié
Nature Communications volume 15, Article number: 3494 (2024) Cite this article
Abstract
H9N2 avian influenza viruses (AIVs) are a major concern for the poultry sector and human health in countries where this subtype is endemic. By fitting a model simulating H9N2 AIV transmission to data from a field experiment, we characterise the epidemiology of the virus in a live bird market in Bangladesh. Many supplied birds arrive already exposed to H9N2 AIVs, resulting in many broiler chickens entering the market as infected, and many indigenous backyard chickens entering with pre-existing immunity. Most susceptible chickens become infected within one day spent at the market, owing to high levels of viral transmission within market and short latent periods, as brief as 5.3 hours. Although H9N2 AIV transmission can be substantially reduced under moderate levels of cleaning and disinfection, effective risk mitigation also requires a range of additional interventions targeting markets and other nodes along the poultry production and distribution network.
Introduction
H9N2 Avian influenza virus (AIV) is considered to be the most prevalent AIV in poultry globally1. Despite being classified as a low pathogenic virus, H9N2 AIV is responsible for substantial economic loss for the poultry industry2,3. Infection is typically associated with moderate to severe respiratory symptoms, delayed growth, reduced egg production and increased mortality, especially when co-infection with other pathogens is involved4. Some H9N2 AIV lineages are known to be zoonotic, with resulting symptoms being typically mild. Co-circulation with other AIV subtypes may lead to the emergence of reassortant viruses with increased pathogenicity and/or zoonotic potential5,6,7. H9N2 appears to be involved in the origin of several novel zoonotic AIVs, whose number has been rapidly increasing since 20138. AIVs with H9N2-derived genes include H7N99, H5N1, H10N810,11,12 and, more recently, H3N813.
In many Asian countries, the prevalence of H9N2 AIVs is particularly high in live bird markets (LBMs), with estimates in Bangladeshi markets as high as 80%14,15. LBMs play a central role in the marketing of poultry in developing countries, being the place of choice for many people to purchase meat for consumption. At the same time, the high prevalence of AIV infection among traded poultry is concerning due to the risk of zoonotic spillover to humans5,16,17. In LBMs, the latter may be exposed to AIV through contaminated dust particles, water, surfaces and the slaughtering of infected birds. LBMs are also known to promote the mixing and evolution of AIVs, in that they enable the intermingling of multiple poultry species from many distant locations and diverse farming systems18,19,20. Over the last 25 years, public health concerns around LBMs have prompted health authorities in several Asian countries to take steps to control AIV transmission in these settings; adopted measures included enhanced hygiene protocols, bans on overnight poultry storage, as well as periodic rest days21,22,23,24,25,26. Temporary and permanent market shutdowns have also been employed in response to outbreaks of emerging zoonotic AIVs27...