Investigating poultry trade patterns to guide avian influenza surveillance and control: a case study in Vietnam

Live bird markets are often the focus of surveillance activities monitoring avian influenza viruses (AIV) circulating in poultry. However, in order to ensure a high sensitivity of virus detection and effectiveness of management actions, poultry management practices features influencing AIV dynamics need to be accounted for in the design of surveillance programmes. In order to address this knowledge gap, a cross-sectional survey was conducted through interviews with 791 traders in 18 Vietnamese live bird markets. Markets greatly differed according to the sources from which poultry was obtained, and their connections to other markets through the movements of their traders. These features, which could be informed based on indicators that are easy to measure, suggest that markets could be used as sentinels for monitoring virus strains circulating in specific segments of the poultry production sector. AIV spread within markets was modelled. Due to the high turn-over of poultry, viral amplification was likely to be minimal in most of the largest markets. However, due to the large number of birds being introduced each day, and challenges related to cleaning and disinfection, environmental accumulation of viruses at markets may take place, posing a threat to the poultry production sector and to public health

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

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

Economic factors influencing zoonotic disease dynamics: demand for poultry meat and seasonal transmission of avian influenza in Vietnam

While climate is often presented as a key factor influencing the seasonality of diseases, the importance of anthropogenic factors is less commonly evaluated. Using a combination of methods-wavelet analysis, economic analysis, statistical and disease transmission modelling-we aimed to explore the influence of climatic and economic factors on the seasonality of H5N1 Highly Pathogenic Avian Influenza in the domestic poultry population of Vietnam. We found that while climatic variables are associated with seasonal variation in the incidence of avian influenza outbreaks in the North of the country, this is not the case in the Centre and the South. In contrast, temporal patterns of H5N1 incidence are similar across these 3 regions: periods of high H5N1 incidence coincide with Lunar New Year festival, occurring in January-February, in the 3 climatic regions for 5 out of the 8 study years. Yet, daily poultry meat consumption drastically increases during Lunar New Year festival throughout the country. To meet this rise in demand, poultry production and trade are expected to peak around the festival period, promoting viral spread, which we demonstrated using a stochastic disease transmission model. This study illustrates the way in which economic factors may influence the dynamics of livestock pathogens

Semiconductive Nb-doped BaTiO3 films grown by pulsed injection metalorganic chemical vapor deposition

International audienc

THIN FILM OF CERAMIC OXIDES BY MODIFIED CVD

Nous décrivons un procédé de dépôt utilisant la pyrolyse d'un aérosol généré par ultrasons (procédé Pyrosol). La réaction chimique sur le substrat chauffé est de type CVD. Nous avons étudié les conditions expérimentales de dépôt de zircone stabilisée à l'oxyde d'Yttrium, en vue de la réalisation de microcapteurs de gaz. Nous obtenons directement la phase cubique de la zircone stabilisée. Comme application en tant que média pour l'enregistrement magnéto-optique nous avons obtenu des couches de Y3Fe5O12 non orientées pour des dépôts sur quartz et des couches épitaxiées pour des dépôts sur des substrats monocristallins de GGG.We describe a deposition process which uses the pyrolysis of an aerosol produced by ultrasonic spraying (Pyrosol process). The chemical reaction on the heated substrate corresponds to CVD. Experimental deposition conditions of yttria stabilized zirconia have been studied with the aim of realizing microionic gas sensors. We obtain directly the stabilized cubic phase. For magneto-optical information storage or magneto-optical display devices we have deposited Y3Fe5O12 garnet thin films. Good quality thin layers were obtained, not textured on quartz substrates and epitaxialy grown on GGG substrates