Low pathogenic avian influenza and live bird markets in Southern California

In this project we evaluated the domestic poultry hosts, the LBM environment, and the transmission characteristics of LPAIV H6N2. The purpose was to provide information for improving LPAIV prevention and control programs in live bird markets (LBMs).;LBM owners in Southern California and their poultry suppliers have cooperatively developed the California Custom Slaughter LPAI Control Program with the United States Department of Agriculture (USDA), California Department of Food and Agriculture (CDFA), and the University of California, Davis. From survey data we described the LBM system, including biosecurity practices, direct and indirect contacts between markets.;We evaluated survey data using social network analysis (SNA) methods to identify possible risk groups. The volume of birds sold in LBMs was independent of live bird delivery frequency and common bird suppliers. LBMs that sold rabbits or spent hens had a significantly greater number of live bird suppliers, frequency of weekly deliveries of live birds, and greater SNA centrality scores than LBMs that did not sell rabbits or spent hens.;Samples were collected from birds in LBMs to estimate the prevalence of low pathogenic avian influenza (LPAI) shedding after detection of the virus by routine surveillance in October-November, 2005 in three LBMs. A stratified systematic sampling method was used to collected samples at each LBM. RT-PCR was performed on samples collected from birds. Subtyping and sequencing of the hemagglutinin, neuraminidase and non-structure genes was performed on AIV positive samples.;A transmission experiment using the types of birds sold in LBMs located in Southern California was conducted simulating the LBM setting to evaluate the modes of AIV transmission between birds. Aerosol droplet exposure was found to be the most important route of transmission for H6N2 AIV and there was no observable effect of handling infectious chickens as a route of transmission for H6N2 AIV. The importance of AIV spread by fecal exposure to infected chickens was inconclusive. This strain of H6N2 LPAIV is not easily transmitted to ducks from chickens; however, it is readily transmitted to quail by indirect contact with infectious chickens.