Classical swine fever

Transmission of disease takes place through direct contact between animals (secretions, excretions, semen, blood) or indirect contact through vehicles, clothes, instruments, needles, and insufficiently cooked waste food fed to pigs. It can also be spread by pig traders and farm visitors. Transplacental infection of foeti in the uterus can also take place. In areas with a high density of pigs spread of virus easily occurs between neighbouring pig holdings. Trade in live pigs and pig products (fresh pig meat and certain meat-based products) plays an important role in spreading the disease.

The clinical signs of CSF are extremely variable and may be mistaken for many other diseases. CSF causes fever, conjunctivitis, skin lesions, convulsions and often (particularly in young animals) leads to death of the animal within less than four weeks. Severity of symptoms mainly depends on the age of the animal and virus virulence. Usually young animals are affected more severely than older animals. In older breeding pigs the course of the infection is often mild or even subclinical. The symptoms are indistinguishable from those of African swine fever.

More information:

Classical Swine Fever (DEFRA)

Community Reference laboratory on Classical Swine Fever (TiHo)

EU information on Classical Swine Fever

Technical disease cards OIE

EPIZONE and classical swine fever

Diagnostics

• Data on CSF reference material (virus isolates, sera, monoclonal antibodies, tissue samples) and images of the clinical disease were collected in databases and made accessible to all partner organizations.
• Numerous activities for harmonization and standardization of real time RT-PCR assays for CSFV. 
• Reference material for PCR validation was produced. The so-called "EPIZONE REFERENCE RNA PANEL CSFV" represented full-length viral RNAs of 31 CSFV strains and related pestiviruses. This first EPIZONE RNA panel can be used by all EPIZONE partners for a further harmonization of the CSFV real-time PCR diagnostics, DNA-Chip diagnostics as well as pen-site testing. 
• A list of validated, functional real-time RT-PCR assays useful for the sensitive, specific and robust detection of CSFV based on information of collected data has been compiled and summarized in a review article. 
• A real-time PCR ring trial succeeded in the optimization of CSFV-specific real-time RT-PCR diagnostics in the EU laboratories. Laboratories with a sub-optimal protocol changed to a more sensitive and specific method or improved their own protocol 
• A "real-time PCR diagnostics" workshop was realized for 20 real-time PCR specialists from 12 different EPIZONE partner institutes.
• Available information on DIVA diagnostics in CSFV was collected in a review where the strategy towards CSF was compared to the DIVA strategies towards HPAI and FMDV
• The interaction of experts of EPIZONE in the field of "pen-side tests" was enhanced and the different methods and experiences of the different groups were exchanged and discussed.
• CSFV antibody specific ELISA's were used in a ring trial to test sera from pigs experimentally vaccinated with different CSFV strains, other pestiviruses, commercially available vaccines, and new chimeric DIVA vaccines. The ELISAs were evaluated on their practicability, reproducibility, diagnostic sensitivity and specificity and their potential use as DIVA ELISA tests.  
• Genetic DIVA based on detection and differentiation of nucleic acid from some of the major live vaccines and wild-type CSFV have been implemented and partly validated.

Intervention Strategies

• A better knowledge of the functional states (cytokines, chemokines, co-stimulatory molecules etc.) of antigen presenting cells and the influence caused by epizootic diseases will improve the design of vaccine formulation and will provide the basis for a better and more rational use of adjuvants and immunomodulators. Viruses used for the in vitroand in vivo infection experiments included classical swine fever virus (CSFV),
• Experimental investigations continued to characterize the role of T cells and antigen presenting cells in different infection models including CSFV. The results of this reporting period contribute to a better understanding of the immune response to diseases caused by epizootic infections and to the characterization of immune correlates of protection against these diseases.
• The complex use of DIVA vaccines in eradication of animal diseases from an endemic or epidemic situation has been evaluated based on demands and evaluation of CSF vaccines from a European perspective and has been discussed in a draft paper 

• A list of data of potential antiviral agents interfering with membrane binding, genome replication or gene silencing (siRNA) specific inhibiting either CSFV or morbilliviruses was created.

Surveillance and Epidemiology

• Clinical support systems are evaluated based on information obtained after the CSFV outbreak in The Netherlands 1997-98. Supplementary data from experimental infections on a wide variety of CSFV strains and data from clinical suspicions in the field are gathered to improve the system and turn it into an international hand held, computer aided system for easier and more uniform field clinical evaluation. (WP 7.3, CSS-CSFV).

Risk Assessment

• Evaluation of a technical aid that helps to assess the risk that classical swine fever is present in a herd. The results represent a big step forward towards to feeding the electronic tool with the field data required to detect classical swine fever in affected farms in different countries.