Analysis of clinical samples for early detection of classical swine fever during infection with low, moderate, and highly virulent strains in relation to the onset of clinical signs

► CSFV is detected prior to clinical signs among moderate and low virulent infections. ► Blood and tonsil scrapings are ideal from live pigs, tonsil and serum at slaughter. ► Tonsil, blood and tonsil scraping are superior samples by rRT-PCR and virus isolation. ► Nasal swab samples performed poorly for low, moderate and highly virulent infections.