Research in swine fever is contributing to improve the contingency preparedness in collaboration with the Danish National Swine Fever Laboratory, Lindholm. The main task is to study the diagnostic methods and the pathogenesis of classical swine fever (CSF) caused by classical swine fever virus. The clinical signs caused by CSF differ largely depending on the viral strain and the breed of the pigs. Some low-virulent strains may not even give suspicion of CSF before the pigs are well again whereas other strains cause serious disease with high fever, lack of appetite and hemorrhages. In most cases, CSFV can be detected in pig serum and tonsils a few days after infection; focus is on the optimal material for the diagnosis and the fastest detection of CSFV. Furthermore, the immunological aspects of CSFV may elucidate some of the unsolved questions concerning the underlying disease mechanisms. In addition, swine fever infections in pigs constitute a unique animal model for human viral hemorrhagic fevers like Dengue fever. The impact of cytokines and the changes in the distribution of white blood cells seems to be comparable for viral hemorrhagic fevers in swine and man.
Denmark is one of the top-exporters of pig meat and live pigs, not only within the EU but also to Japan and USA import considerable amounts. To retain this export the high sanitary status of Danish pigs need to be maintained. One single case of CSFV would impair the export potentials for several years and therefore large efforts are used to keep CSF out of Denmark, which has been free from this disease since 1933. Therefore, import of live pigs is only allowed from countries which do not have CSF and as an extra security pigs are kept in quarantine and blood sampled before introduction into the Danish domestic pig populations. For imported pig meat, it is not possible to obtain a blood sample; therefore alternative methods, such as detection of virus in meat juice are currently under validation at Lindholm.
With the increased globalisation the risk of introduction of CSFV has increased. Therefore, we also conduct studies on vaccines which could Differentiate Infected from Vaccinated Animals (DIVA) technologies. Our knowledge of how CSF develops in weaner pigs allows us to test the efficacy of different vaccine types. Vaccination can only be performed if permission is obtained within EU but any vaccination will delay the time until national status of freedom from CSFV can be regained. The traditional live vaccine C-strain, used in a number of countries outside the EU, is highly effective but do not have the DIVA principle, after vaccination all pigs will be antibody positive even if they have never encountered wild type virus. At Lindholm, we have research, funded both nationally and from EU, on DIVA vaccines and DIVA diagnostics for CSFV. If solid protection can be achieved using DIVA vaccines, many pigs will be saved even if CSFV is present in the neighbouring herds and needless culling of suspected herds will be avoided.
CSF is a pestivirus, closely related to Bovine Viral Diarrhoea virus (BVDV). Recently BVD was eradicated in Denmark and at present occasional relapses of BVD occur, these are closely followed by the cattle organisation in collaboration with the laboratory at Lindholm.
Recently, new interests have arisen in African swine fever (ASF), a viral disease indistinguishable from CSFV but caused by a different virus. ASF has an intermittent tick host and is now spreading from Georgia through Russia. Climatic changes seem to favour the spread of vector borne diseases to more northbound regions. Suspicions of ASF are also analysed at Lindholm.
Contact professor Åse Uttenthal