Classical Swine Fever Virus

Classical swine fever virus (CSFV), or hog cholera, causes serious losses in the pig industry because it is highly pathogenic and may cause widespread deaths. Pigs infected with highly virulent CSFV strains may shed high amounts of virus before showing clinical signs of the disease. Animals that survive an acute or subacute infection develop antibodies and will no longer spread the virus. Moderately virulent, less pathogenic strains may lead to chronic infection when pigs excrete the virus continuously or intermittently until death. Congenital infection may result in abortion, mummified fetuses, stillborn and/or weak piglets, or embryonic malformations.

The most frequent outcome of congenital infection with low virulent strains is the birth of persistently infected piglets spreading the virus without the signs of the disease in the absence of immune response. All animals shedding the virus need to be identified and removed from the herd to prevent the spread of infection. Pigs may also be infected with bovine viral diarrhea virus (BVDV) or border disease virus (BDV). Although these infections in pigs are usually mild and self-limiting, it is important to reliably distinguish them from the CSFV infection.

The field experience and EU regulation actually in place are also asking for a DIVA system that permits the differentiation between SCF-negative animals and animals vaccinated with an E2 subunit vaccine (Erns-negative) from CSF-infected animals (Erns-positive).