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.
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