Classical Swine Fever | Diagnosis
Diagnosing the disease
Viral isolation in cell culture is the most largely accepted method for diagnosis of CSF. The virus can be isolated from blood (buffy coat cells) or suspensions of spleen, tonsils, lymph nodes, parotid glands, and kidneys. Since CSF virus is not cytopathogenic, specific antibodies must be used for viral detection in cell culture. Monoclonal antibodies are used for differentiation from ruminant pestisviruses (BVD, border disease). The drawback for viral isolation is that this is a time consuming procedure that takes at least 3 days and final results may not be available up to 7 days after the samples are received at the laboratory.
Although less sensitive than viral isolation, direct detection of viral antigens in tissue sections by fluorescent antibodies is a rapid alternative. Detection of viral antigens can also be accomplished by ELISA, although the sensitivity is also low.
Although not largely accepted and standardized, detection of viral RNA by RT-PCR is a very promising diagnostic approach for CSF. Importantly, subsequent sequencing of the amplified RT-PCR product (5’nontranslated region) allow discrimination between different CSF virus isolates.
Serologic tests for CSF include virus neutralization, which is largely accepted but time consuming, and ELISA. Virus neutralization is the most sensitive and specific method for CSF antibody detection, but cross-reaction with antibodies against ruminant pestisviruses must be ruled out by doing a second neutralization test. Although ELISA is less sensitive, this method is useful for screening large number of samples.
Differential diagnoses
Differential diagnoses include other febrile and hemorrhagic disease of pigs such as African Swine Fever, sepsis, anti-coagulant poisoning (coumarin derivatives), and hemolytic disease of the newborn.
Infection with low virulence strains must be differentiated from a variety of other causes of low reproductive performance and congenital tremors, that include: pseudorabies, parvovirus, BVD and border disease, porcine circovirus, and other non-infectious causes. Control >>
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