Risk Factor Analysis for the Farm Level Aujeszkey’s Disease Infection on Pig Farms in Japan

Abstract

The eradication program of Aujeszkey’s Disease (AD) has been in operation since 1991 by Ministry of Agriculture, Forestry and Fisheries, however, infected farms still exist in Kanto and Kyusyu regions to date in Japan. In the present study, a cross-sectional study was conducted in order to determine the risk factors associated with the farm-level AD infection in pig farms. Data were obtained through a postal survey in Kanto region using a prepared questionnaire that included results of AD testings and its vaccination program, and herd management practice As a result, 329 out of 960 requested farms agreed with the cooperation and sent back the questionnaire.
Defining the infected farm as a farm with one or more ELISA positive pigs, the farm-level prevalence was 41.5%. After the multivariate logistic regression analysis, introduction of purchased pigs without any AD testings (odds ratio=2.2, p<0.05) and no prohibition practice for the vehicles and visitors entering farms (odds ratio=2.5, p<0.05) were determined as the significant risk factors to be the infected farm. These results imply that negative confirmation for AD to the purchased animals prior to the introduction and control of the vehicles and persons at farm entrance were the crucial point to prevent the AD introduction into the farms. In addition, AD vaccination to all pigs was performed in more than 80% of both infected and uninfected farms, which seemed to be the preferable situation for the region-wide control measures. On the other hand, less than 40% of both infected and uninfected farms conducted the disinfection of vehicles on their farm entrance. For the efficient AD control measures, improvement of basic farm bio-security was also thought to be important.