Epidemiological characterization and network analysis of Colorado's backyard bird population, 2008-2009
Date
2011
Authors
Smith, Emily Ione, author
Reif, John S., advisor
Pabilonia, Kristy L., committee member
Hill, Ashley E., committee member
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Abstract
Backyard bird flocks are a minimally characterized population that could be influential in the spread of HPAI among bird populations, humans, and other animals. The general objectives of this study were to collect basic information on Colorado's backyard bird populations to provide an epidemiological characterization of the backyard flocks in Colorado from March 2008 to March 2009, specifically focusing on an association between poor health among the birds and the movement of birds by humans; and also to perform a network analysis evaluating potential relationships between backyard flocks and poultry exhibitions, and bird markets. Flock information was gathered by questionnaire sent to backyard flock owners. Questions covered the topics of backyard flock characteristics, movement, health, biosecurity, and human interaction. The descriptive statistical analyses were performed using the statistical software program, SPSS Graduate Pack 16.0© 2007. The network analyses were performed using the software packages for social network analysis, UCINET 6 for Windows- Version 6.230 © 2002 and NetDraw 2.087- Network Visualization Software © 2002. A total of 317 surveys were returned out of 807 eligible surveys, providing a participation rate of 39.28%. In 2008, the backyard bird population surveyed consisted primarily of layer chickens (37.43%), waterfowl (14.92%), and show chickens (14.09%). We found that 68.6% of the flocks were smaller than 50 birds and were mostly kept as a source of food for the family (86.44%). A large number of flocks were also used for participation in 4-H or Future Farmers of America (FFA) or just kept as pets. The most commonly reported health problems included unexplained death (12.93%), external parasites (23.97%), respiratory problems (12.93%), and diarrhea (12.3%). Almost half of the participants reported moving their birds off of their home premises at least once during the year. Most of these birds were taken to fairs or bird shows (31.43%). We found that the flocks with birds that were moved frequently were more likely to develop respiratory problems than those that did not move their birds (1 time, (0.7, 5.11); 2-3 times, (1.37, 9.16); >4 times, (3.33, 19.94)). With network analysis, we established the presence of a highly connected network among backyard bird flocks and poultry events. The event and flock networks were heterogeneous, small world, and scale-free networks with a few central events or flocks that were highly connected to a number of the other flocks/events. The information gathered provides basic descriptive information useful for the development of future studies of this population or for integration into HPAI surveillance or HPAI control programs by providing essential population data for backyard bird populations. The information provided by the network analysis can be used to predict the potential spread of disease in this population and for targeted disease control.
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Subject
avian influenza
network analysis
epidemiology
Colorado
backyard birds