African swine fever

A reservoir of ASFV is maintained in sub-Saharan Africa in a wildlife cycle involving warthogs and Ornithodoros species of soft ticks. These hosts may be persistently infected over long periods with no disease signs. Pigs can be infected by direct contact with infected pigs, by ingestion of infected material or by bites from infected ticks. European wild boar show similar signs of infection to domestic pigs and could act as a virus reservoir. 

ASF is currently endemic in most sub-Saharan African countries, in Sardinia and in areas within the Trans-Caucasus region and Russian Federation to which it was introduced in 2007.  ASFV is a large double-stranded DNA virus and is currently the only member of the Asfarvirus family.

There is no treatment for this disease, and at present there is also no vaccine.

EPIZONE and African swine fever

Diagnostics

• Pen-side tests: The direct amplification of both RNA and DNA for ASFV from Whatman filter papers was demonstrated, which will provide a basis for easy sample storage and distribution within the EPIZONE network and in developing countries. Nucleic acid amplification using isothermal PCR methods have been developed and have the potential to be used at the pen-side.  

Intervention strategies

• The ASFV interest group has organised joint vaccine experiments including funding from other projects and expertise from different partners. These ASFV vaccine experiments include experiments  to test the ability of attenuated ASFV vaccine strains to provide cross-protection against isolates from the same and different genotypes. Different prime boost strategies for delivery of potentially protective antigens are also being tested. 

• 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 vitro and in vivo infection experiments included African swine fever virus (ASFV). 

Risk Assessment

• An expert opinion workshop was held to assess the potential impact of climate change on spread of tick borne diseases in the EU. The opinion was that climate change could result in a wider distribution in Europe of Ornithodoros spp ticks increasing the chances for a virus reservoir to be maintained. However, since ASF can be transmitted by other routes, potential for introduction and spread within the EU is not dependent on the presence of the tick vector.