Swine fever: classical swine fever and African swine fever

African swine fever (ASF) and classical swine fever (CSF) are potentially devastating viral diseases of swine that would have an extremely negative effect on both animal health and the agricultural economy in general if introduced into North American swine herds. In addition to the obvious costs of controlling an epizootic, a severe consequence of the incursion of either CSF or ASF would be the immediate loss of most export markets for all pork and pork products. Both of these highly contagious diseases can occur in peracute, acute, subacute, or chronic forms, depending primarily on the virulence of the infecting viral strain. The severity of disease seen with peracute and acute forms of CSF and ASE coupled with the extremely high morbidity and mortality rates, should provoke strong suspicions of their presence. It is critically important, however, for producers, veterinarians, and diagnosticians to understand that subacute and chronic disease caused by CSF and ASF viral strains of moderate to low virulence can be clinically and pathologically indistinguishable from a number of common, endemic swine diseases. Similarity to endemic diseases could significantly delay the diagnosis of these forms of CSF or ASF and allow extensive spread within and between herds before definitive diagnosis.