Avian influenza, the wild bird trade and local livelihoods : an interdisciplinary and mixed-methods approach

摘要

Emerging infectious diseases (EID) are increasing in frequency with zoonoses originating in wildlife posing the greatest threat to global health. Highly pathogenic avian influenza (HP AI) strain H5N1 is the most expensive and widespread zoonotic disease to emerge recently. First detected in China in 1996, the virus subsequently spread across Asia, Europe, Africa and the Middle East resulting in tens of millions of animal deaths, primarily poultry as well as 329 fatal human cases. This thesis utilises a range of techniques from multiple disciplines to address questions relating to EID epidemiology and control through to the impacts of HPAI H5N1 at the household level within Vietnam. The methodologies employed include adapting an analytical framework to address a public health problem, semi-structured interviews within central Hanoian and rural Vietnamese households, structured questioning, direct surveys of the live bird markets and key-informant interviews. This thesis has identified rapid growth in the trade and exploitation of birds for cultural and recreational human practices within Vietnam which involve several HP AI H5N1- susceptible species and promote ideal conditions for pathogen transmission. We estimate that three million birds annually are extracted from the wild to supply religious merit release practices in Vietnam alone. At the household level, poultry was found to be an important protein source for urban Vietnamese households and kept primarily for consumption by the majority of rural households. We found urban poultry consumers choose to take protective actions to limit direct exposure to HP AI H5N1 whilst rural households choose to persist with the keeping of household poultry flocks despite the potential risks to household health and livelihood stability. We also identify substantial under-reporting of HPAI H5N1 outbreaks to global surveillance databases and consider the implications of this for HPAI H5N1 surveillance programmes. The thesis concludes by bringing together the different aspects of HPAI H5N1's impacts within Vietnam and emphasises the value of multidisciplinary approaches to studying the impacts of EIDs.