EPINEST, an agent-based model to simulate epidemic dynamics in large-scale poultry production and distribution networks.

The rapid intensification of poultry production raises important concerns about the associated risks of zoonotic infections. Here, we introduce EPINEST (EPIdemic NEtwork Simulation in poultry Transportation systems): an agent-based modelling framework designed to simulate pathogen transmission within realistic poultry production and distribution networks. We provide example applications to broiler production in Bangladesh, but the modular structure of the model allows for easy parameterization to suit specific countries and system configurations. Moreover, the framework enables the replication of a wide range of eco-epidemiological scenarios by incorporating diverse pathogen life-history traits, modes of transmission and interactions between multiple strains and/or pathogens. EPINEST was developed in the context of an interdisciplinary multi-centre study conducted in Bangladesh, India, Vietnam and Sri Lanka, and will facilitate the investigation of the spreading patterns of various health hazards such as avian influenza, Campylobacter, Salmonella and antimicrobial resistance in these countries. Furthermore, this modelling framework holds potential for broader application in veterinary epidemiology and One Health research, extending its relevance beyond poultry to encompass other livestock species and disease systems.

Mapping of dressed and processed poultry products in Bangladesh: Identifying the food safety risks for policy intervention.

Bangladesh's commercial poultry production is growing rapidly, including the commercial processing of poultry. This expansion of poultry processing plants is fueled by the belief that this sub-sector provides safer food and has less food-borne disease risks compared to traditional live bird markets (LBMs). The purpose of this study is to describe Bangladesh's dressed and processed poultry production and distribution network (PDN), identify what and where quality control occurs, and suggest where improvements could be made. Engaging with PDN for dressed and processed poultry, we used in-depth interviews with key informants to identify the stakeholders involved and their connections with other poultry PDNs. In addition, we mapped out the supply and distribution of dressed and processed poultry and quality control processes occurring throughout the network. We argue that dressed and processed poultry PDNs are closely connected with traditional PDNs such as LBMs, with multiple crossover points between them. Also, there is a lack of consistency in quality control testing and a lack of meat traceability. Consequently, perceptions of dressed and processed poultry being safer than birds from LBMs needs to be treated with caution. Otherwise, unsubstantiated consumer confidence in dressed poultry may inadvertently increase the risk of food-borne diseases from these products.

Village and farm-level risk factors for avian influenza infection on backyard chicken farms in Bangladesh.

A cross-sectional study was conducted with 144 small-scale poultry farmers across 42 Bangladeshi villages to explore risk factors associated with avian influenza H5 and H9 seropositivity on backyard chicken farms. Using mixed-effects logistic regression with village as random effect, we identified crow abundance in garbage dumping places and presence of migratory wild birds within villages to be associated with higher odds of H5 and H9 seropositivity. At farm-level, garbage around poultry houses was also associated with higher odds of H5 and H9 seropositivity. In addition, specific trading practices (such as, purchase of chickens from live bird markets (LBM) and neighboring farms to raise them on their own farms, frequency of visits to LBM, purchase of poultry at LBM for consumption) and contact of backyard chickens with other animals (such as, feeding of different poultry species together, using pond water as drinking source for poultry, access of feral and wild animals to poultry houses) were associated with higher odds of H5 or H9 seropositivity. Resource-constrained small-scale poultry farmers should be able to address risk factors identified in this study without requiring large investments into poultry management, thereby reducing the likelihood of avian influenza virus transmission and ultimately occurrence of avian influenza outbreaks.

Discerning risk and uncertainty with "better insurance" - How animal health interventions for village chickens influence farmers' perceptions on the prevention of poultry diseases.

High mortality in young chicks and deaths from Newcastle disease (ND) are the two major constraints to village chicken production in low-and middle-income countries. A 12-month intervention study was conducted across 174 households in two townships of Central Myanmar, to reduce these chicken mortalities. Interventions included ND vaccinations of village chickens and improved chick management. Following the Health Belief Model (HBM) framework, 81 village chicken farmers involved in the intervention study were repeatedly surveyed before and after the interventions to determine the level of change in farmers' knowledge about ND, perceptions about susceptibility and severity of ND virus infection, perceptions about benefits and barriers of ND vaccination, as well as farmers' actions to improve the health status of their birds and to improve biosecurity and ND control measures. Marginal homogeneity tests were used to compare the level of change in farmers' matched responses to individual survey questions before and after the interventions. In addition, confirmatory factor analysis and structural equation modelling was used to create latent variables describing farmers' perceptions about susceptibility and severity of ND in their birds, farmers' perceptions about the barriers and benefits of conducting ND vaccination as well as farmers' cues to action and self-efficacy before and after the interventions. Interventions resulted in 33% more chicks surviving, which resulted in increased sales of birds after they had reached a market age of 7 months. After the interventions, farmers acknowledged the value of protecting birds from ND to increase their income (p = 0.0002). Farmers were also more willing to overcome barriers to vaccination (i.e., 'catching' birds for ND vaccinations) after the interventions (p = 0.0388). Interestingly, after the interventions, fewer farmers were concerned about the risk of their birds becoming infected with ND virus through cock fights and non-confinement (p = 0.0008 and p = 0.00022, respectively), and farmers were more uncertain about the susceptibility of their birds to ND virus infection after the interventions. Surprisingly, farmers became 'less active' in ensuring good biosecurity practices after the interventions: fewer farmers were willing to observe disease signs in village chickens (p < 0.001) and fewer farmers buried dead birds (p < 0.001). Perceived susceptibility was the only HBM component that was significantly reduced (p = 0.014) after the interventions: thus, less farmers were concerned about ND even when using management practices associated with high risk of ND transmission (e.g., cook fights, no confinement). Our results highlight the importance of information campaigns and extension work to ensure farmers maintain a high level of biosecurity when animal health interventions are implemented.