Avian influenza A(H9N2) and A(H5N1) viruses are endemic in Bangladesh’s poultry population and have recently been the target of numerous prevention and control efforts. Due to the limited consistency and continuity of these efforts, they still cause substantial losses to production and threaten the livelihoods of many small-scale poultry farmers. New and innovative approaches are needed to identify points of intervention at which efforts may be effective, including relevant stakeholders and their behaviour, to sustainably constrain maintenance and spread of avian influenza viruses (AIVs) in poultry production systems.

This thesis aims to investigate the role of human behaviour in the epidemiology of infectious diseases affecting Bangladesh’s poultry population. Within the socio-economic and cultural context of the country, I use avian influenza as an example and target two major production systems: broilers, raised on commercial farms, and backyard chickens, raised in rural households. By describing and assessing stakeholder practices putting poultry at an increased risk of infection, I uncover the stage of poultry marketing chains at which exposure to AIVs occurs. I demonstrate and portray risky behaviours displayed by stakeholders to provide insights into potential transmission pathways within the typically complex transport and trade networks. Perceptions of stakeholders related to common interventions are analysed and used to identify groups with similarities.

While AIVs are highly prevalent in Bangladesh’s live bird markets (LBMs), chickens are usually sold within a short period of time. Once introduced, they do not remain long enough to become infected and start shedding AIVs on site. I therefore hypothesise that chickens get exposed at an earlier stage of the marketing chain and are already infected or incubating the disease upon arrival at the LBM. Stepping away from the concept of observational research commonly applied in resource-limited settings, I implemented a controlled field experiment in which chickens were followed and sampled along the entire marketing chain. I designed an intervention, consisting of an alternative marketing chain with enhanced biosecurity standards, to assess whether reducing the risk of infection for chickens during transport and trade decreases their likelihood of shedding AIVs in the LBM. This field experiment comprised of two individual components. First, batches of chickens were purchased from commercial farms or rural households and subjected to the intervention (intervention groups), while complementary batches of chickens were purchased from traders after being sent through conventional marketing chains (control groups). Second, upon arrival at the LBM, intervention and control groups were matched and caged together in market stalls for several days. All chickens were sampled during recruitment, upon arrival as well as 12, 36, and 84 hours later. I explored factors impacting the likelihood of chickens shedding AIVs upon arrival at the LBM and found that longer transport times, as reported for mobile traders, were associated with an increased proportion of AIV-positive chickens. I also developed conditional logistic regression models to compare these proportions at each time point between intervention and control groups. I discovered that the effect of the intervention in reducing the odds of viral shedding was only subtle upon arrival but significant at the following time points. Using discrete-time survival analysis, I then investigated factors impacting the time until chickens turned AIV-positive in the LBM. High turnover of poultry in market stalls and certain cage configurations were associated with increased hazard ratios, while transmission and infection events occurred at a slower rate for backyard chickens compared to broilers.

My research indicates that a substantial proportion of viral shedding observed in Bangladesh’s LBMs results from infection of chickens during transport and trade. I highlight specific stakeholder practices associated with an increased risk of infection and demonstrate that interventions targeting the collection and dissemination of chickens along marketing chains are needed to reduce the prevalence of AIVs in LBMs.

As the field experiment implied that these interventions need to target also earlier stages of poultry marketing chains, I further investigated the role of commercial farms and rural households. I illustrated common characteristics of the two production systems, based on information obtained through a questionnaire survey, and described respective stakeholder practices. Combining both qualitative and quantitative approaches, I also used the Q-methodology to explore the range of perceptions of biosecurity and common farming practices shared among Bangladesh’s broiler farmers. I identified and portrayed three groups of farmers with differing perceptions, for which tailored interventions may be designed. The ‘Committed’ (Group 1) were willing to invest both time and money in biosecurity. Decision-making of the ‘Co-dependent’ (Group 2) was influenced by feed dealers, while the ‘Cautious’ (Group 3) rejected any interference by other stakeholders.

My research proposes how Bangladesh’s broiler farmers may be grouped in relation to shared attitudes and beliefs, which helps to evaluate their group-specific needs. Taking account of their respective perceptions, each group may be addressed in a different way or through separate communication channels to implement tailored and effective interventions.

This thesis uncovers several points of intervention and a variety of stakeholder practices contributing to maintenance and spread of avian influenza in Bangladesh. To sustainably control this as well as other infectious poultry diseases, prevention and control efforts need to be coordinated and extended to all stages of poultry marketing chains. To ensure consistency and continuity, all stakeholders involved need to be included from conceptualisation to implementation as well as in the evaluation of feasibility and effectiveness.