Classical swine fever is a disease that infects wild boars and pigs and had a significant negative economic impact on the swine industry. Oral vaccination is an effective method for controlling classical swine fever. However, information on oral vaccination program has been limited, and its efficiency has not been clarified in Japan. The purpose of this study was to determine the seasonal variation in factors affecting the ingestion of oral vaccines by wild boars. The Gifu Prefecture oral vaccination program was initiated in March 2019, and by February 2021, six seasonal programs had been conducted. We investigated the relationship between the ingestion of oral vaccines by wild boar and pre-baiting, vaccination event, environmental and topographical factors in six vaccination events in three seasonal programs (summer 2019, winter 2019-2020, and spring 2020). This study showed that pre-baiting and the repeated vaccination events were more important factors for the ingestion of oral vaccines by wild boars than topographical and land use factors. Thus, it is a possibility that habitat selection of wild boars is irrelevant in increasing the feeding rate of wild boars on oral vaccines. Consequently, wildlife managers should not only conduct pre-baiting and repeated vaccination events, but also identify areas where wild boars are more abundant immediately prior to oral vaccination programs. To increase the effectiveness of vaccination, it is important for wildlife managers to first implement estimating wild boar density in their habitat areas, followed by efficient oral vaccination programs depending on their densities. Thereafter, they should specifically consider the influence of ingestion by other species and differences in feeding rates by age class.
Keywords: Bait vaccine; Land use; Pre-baiting; Seasonal variation; Topographical factors; Wild boar density.
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