Abstract: In order to determine the reason of weaned piglets’ death on an intensive pig farm in Guizhou province, the infected weaned piglets from this pig farm were detected using epidemiological survey, autopsy pathological observation, anatomic pathological diagnosis and RT-PCR method. The results showed that from epidemiological survey and autopsy pathological observation, we primarily diagnosed the pig farm, which was suspected infected by classic swine fever virus (CSFV) and bacteria. The RT-PCR result confirmed that the infected pigs were infected by CSFV and the bacterium was confirmed as Streptococcus suis by bacteria culture and isolation, biochemical character identification and animal pathogenicity test. Comprehensive above test results showed that mixed infection of CSFV and Streptococcus suis were the cause of the pig death in this pig farm.

Key words: classic swine fever (CSF); Streptococcus suis; mixed infection; diagnosis