Classical swine fever: Different clinical forms can be caused by a single strain of the virus

Classical swine fever (CSF) is a highly contagious viral disease of domestic and wild pigs. It can be manifested in different clinical forms, viz: acute, chronic and inapparent forms. While some workers have opined that the acute disease results from infection with virulent strains of the virus and the chronic or clinically inapparent forms due to infection with low virulent strains of the virus, others have opined that it is dependent on the dose of the virus, age, breed and health status of the host. In the present study, samples from CSF affected pigs representing three different clinical forms of the disease were tested by a highly sensitive and specific real-time RT-PCR to determine whether the infecting strain of CSFV was identical or varied in each clinical form. The results indicated that the same strain of virus was involved in the causation of acute, chronic and clinically inapparent forms of the disease.