Some problems in veterinary medicine disease mapping

摘要

This dissertation examines the prevalence rates of two US canine pet diseases, heartworm and anaplasmosis. Specifically, a massive data set obtained from the Companion Animal Parasite Council (CAPC) is analyzed to help describe these two diseases. The data sets consist of the number of positive tests and the total number of tests performed on a county-by-county basis in the United States (US) over 2011-2013. Data set for both disease contains millions of test results that have not been previously analyzed before.;CAPC canine heartworm data is used to clarify the spatial prevalence of heartworm in the US. Factors thought to influence the spatial prevalence of disease, as identified in a recent CAPC workshop, are discussed and analyzed for predictive power in describing prevalence rates of canine heartworm in the contiguous United States. CAPC's data set contains county-by-county results of over nine million heartworm tests conducted during 2011 and 2012. All of the examined factors appear to have power in predicting heartworm prevalence, including median household income, annual temperature, county elevation, and presence of the mosquitoes Aedes trivittatus, Aedes sierrensis, and Culex quinquefasciatus. Interactions among factors also exist.;Factors identified by the prostriate tick working group, assembled at a CAPC meeting in Atlanta in June 2012, were analyzed for their ability to explain/predict regional prevalence rates of canine anaplasmosis within the conterminous US. This work explores spatial, temporal, environmental, economic, and vector-born factors that were suggested to influence anaplasmosis prevalence rates. The examined factors include climate conditions (annual temperature, precipitation, and relative humidity), socio-economic conditions (population density, household income), local topography (surface water, forestation coverage, and elevation), and vector presence (measures of wildlife/human interaction, such as deer/car strikes). These factors were then analyzed with CAPC's anaplasmosis test results, which contain approximately 4 million test results conducted during the years of 2011 to 2013. Two methods were applied to analyze the data, and both of the results are presented in this paper. Both of the results show that most of the factors considered in this paper are significant in influencing anaplasmosis prevalence.;The factor lists for both diseases are likely incomplete due to data deficiencies. For example, coyotes and feral dogs are known reservoirs of heartworm infection. Unfortunately, no complete count of their populations are available throughout the US on any good spatial scale. Model performance should improve as more factors are collected. The regression models considered are currently being explored to forecast future prevalence of each disease.