EPIDEMIOLOGIC ANALYSES OF SPATIAL CLUSTERING OF BOVINE EPHEMERAL FEVER OUTBREAKS .2. PRINCIPAL COMPONENT ANALYSIS

The principal component analysis (PCA) was applied to analyze a correlation matrix of three variables on epidemic data of bovine ephemeral fever (BEF) outbreaks. These original data were summarized from the official outbreak report of Fukuoka Prefecture. The first and the second principal components of the PCA were interpreted as the infectious potency due to BEF virus and the prevention against BEF virus infection, respectively. The BEF outbreak areas were able to be classified epidemically into 4 groups by using the two principal components. The valuable epidemiological insights can be reasonably obtained from an application of the PCA. The results provided an important information for a further BEF vaccination campaign in the western part of Japan.