H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks

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 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.

Continuing professional development for veterinarians in a changing world

The veterinary profession has time and again successfully adapted to new challenges and developments, with considerable evolution of the skills needed. Different contexts, production systems and societal requirements continue to shape the profession, resulting in an increasing demand for specialisation, interdisciplinary collaboration along value chains, and preparedness for the omnipresent risk of emerging diseases. To keep up with changes, new insights, advances in research and novel ways to address challenges, continuing professional development (CPD) and the adaptation and updating of the veterinary curriculum have been essential to maintain and enhance the quality and performance of Veterinary Services. This paper reviews actors involved in the provision of Veterinary Services and discusses how vital CPD is in addressing current and future challenges, by focusing on veterinarians and allied veterinary professionals. The authors examine how providers of CPD contribute to the system and how the internal and external factors of a cohort or individual affect the quality and impact of capacity development. The paper further examines the landscape of veterinary CPD in terms of organisational structures, pedagogical approaches, the transition from input- to outcome-based learning, modern delivery tools, and the demands on the different actors involved in the delivery of animal health services. The authors conclude that CPD is essential if the quality of Veterinary Services is to keep pace with the ever-increasing and evolving demands of the 21st century. A CPD programme should therefore be constructed in a way that is tailored to the needs of veterinary professionals and to the requirements of their workplace, whether they work with animal keepers, livestock value chains, national governments or international regulatory bodies. An optimised and successful veterinary sector requires an evidencebased CPD programme that keeps those professionals who are involved in the delivery of animal health services both competent and relevant in a changing world.

A large-scale study of a poultry trading network in Bangladesh: implications for control and surveillance of avian influenza viruses

BACKGROUND

Since its first report in 2007, avian influenza (AI) has been endemic in Bangladesh. While live poultry marketing is widespread throughout the country and known to influence AI dissemination and persistence, trading patterns have not been described. The aim of this study is to assess poultry trading practices and features of the poultry trading networks which could promote AI spread, and their potential implications for disease control and surveillance. Data on poultry trading practices was collected from 849 poultry traders during a cross-sectional survey in 138 live bird markets (LBMs) across 17 different districts of Bangladesh. The quantity and origins of traded poultry were assessed for each poultry type in surveyed LBMs. The network of contacts between farms and LBMs resulting from commercial movements of live poultry was constructed to assess its connectivity and to identify the key premises influencing it.

RESULTS

Poultry trading practices varied according to the size of the LBMs and to the type of poultry traded. Industrial broiler chickens, the most commonly traded poultry, were generally sold in LBMs close to their production areas, whereas ducks and backyard chickens were moved over longer distances, and their transport involved several intermediates. The poultry trading network composed of 445 nodes (73.2% were LBMs) was highly connected and disassortative. However, the removal of only 5.6% of the nodes (25 LBMs with the highest betweenness scores), reduced the network's connectedness, and the maximum size of output and input domains by more than 50%.

CONCLUSIONS

Poultry types need to be discriminated in order to understand the way in which poultry trading networks are shaped, and the level of risk of disease spread that these networks may promote. Knowledge of the network structure could be used to target control and surveillance interventions to a small number of LBMs.