Update on classical swine fever (hog cholera)

Abstract

Classical swine fever (CSF), commonly known in the United States as hog cholera, is a highly contagious viral disease of swine caused by a Pestivirus related to bovine virus diarrhea (BVD) and border disease virus (BDV) of sheep. Virulence varies from mild to severe. Most current outbreaks are associated with moderately virulent strains. The classic virulent disease is now rather uncommon. Classic highly virulent disease characteristically presents with high fever, extreme lethargy, hemorrhages in numerous organs, neurological signs, leukocytopenia, and high mortality. Moderately virulent disease causes high fever, mild lethargy, mild hemorrhages in lymphoid organs, transient leukocytopenia (or none), and low mortality. Recovered pigs may have a chronic disease with intermittent fever and poor reproductive performance. Pigs born of infected sows may be persistently infected and carry the virus for life, but with no immune response. The virus can also be transmitted in semen to sows. An outbreak of moderately virulent CSF may go undiagnosed for months due to its mild nature and few lesions.