Laboratory experience during the classical swine fever virus epizootic in the Netherlands in 1997-1998

From February 1997 till May 1998 the national reference laboratory for clas sical swine fever (CSF) in the Netherlands was confronted with millions of samples taken from pigs during an outbreak of CSF ina pig dense region. In a limited period major logistic problems needed to be solved regarding the processing of samples and information at the laboratory facilities. In total over 2.3 million samples were examined by different CSF diagnostic methods. The majority (approximately 2.1 million) of these samples were bl ood samples which were tested for CSF serum antibody in a semi-automated EL ISA. Approximately 166,000 samples were examined for the presence of CSF vi rus or viral antigen. Automated preparation and testing of blood samples fo r CSF serum antibody, the obligatory identification and registration system of pig holdings and the computerised laboratory management system made it possible to process the huge amount of samples and information presented in a limited period. The majority of the test results was sent to the veterin ary authorities via e-mail or a computerised fax system. Of the 429 outbreaks 82% were detected via a direct immunofluorescence tech nique performed on cryostat sections of the tonsil. The sampling of clinica lly suspected pigs ('guided' sampling) for this diagnostic method provided rapid positive and negative results and thus played a paramount role during the eradication campaign. Serological surveys identified 13.5% of the infe cted pig holdings: such surveys proved very effective in the screening of h oldings which were subjected to restrictions (protection or surveillance zo nes) for many months. Virus isolation performed on different types of sampl es detected 4.5% of the infected pig holdings. In conclusion, analysis of data collected in the laboratory and epidemiolog ical analysis should result in an improved eradication plan for the future control of outbreaks of CSF in the Netherlands supported by optimised CSF d iagnostic methods. (C) 2000 Elsevier Science B.V. All rights reserved.