| Summary: | 碩士 === 國立中興大學 === 獸醫病理學研究所 === 89 === Classical swine fever (CSF) and foot and mouth disease are programmed diseases to be eradicated in Taiwan. To survey the prevalence of classical swine fever (CSF) virus contamination and persistence in pig farms in Taiwan a cross-section study was undertaken in 1998. Two hundred and twenty-three sick nursery pigs from 61 farrowing-to-finishing pig farms in three counties of central Taiwan were submitted for CSF diagnosis using pathology, RT-PCR technique, and Ag-ELISA detection. All submitted cases did not show typical acute CSF virus symptoms and lesion as extensive hemorrhagic lesions in skin and visceral organs. The presumed chronic CSF virus infection was diagnosed by accumulation of CSF-associated lesion scores (over33 points) and RT-PCR examination. The contamination figure was expressed at farm level. The results showed that 16 out of 61 farms (26.2%) were suspected with chronic CSF virus contamination. To confirm CSF virus persistence in those pig farms, the similar examinations were repeated on previous 14 CSF virus contaminated pigs farm one year later. There were 7 pig farms (50.0%; 7/14) still showing CSF virus contamination. Moreover, antigen ELISA to detect Erns in serum from sick nursery pigs (5 to 10 samples each herd) was also used to detect virus infection in above contaminated pig farms. The results displayed that 7 out of 12 pig farms were positive for Erns detection. As labor or less sensitivity and specificity of above methods to elucidate chronic CSF virus contamination and persistence, detection of E2 antibody response in sentinel animals as contamination figure was then evaluated in four pig farms. Except DB pig farm, other three pig farms (DA, DC, AA) showed different levels of seroconversion of E2 antibody of sentinel pigs at 3-4 months old. Those data indicated that chronic CSF virus might have widely persisted in many pig farms in Taiwan. Therefore, to eradicate CSF virus ion from pig farms a proper vaccination program with safe preventive procedures, including disinfection, blocking virus transmission, intensively culling sick pigs, and monitor system are required.
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