Changes

===Laboratory Tests===

===Laboratory Tests===

The most frequently used diagnostic tests are an ELISA and an indirect fluorescent antibody test. Both of these tests measure IgG antibodies against PRRS virus, which can be detected from 7-10 days post-infection. Titres persist for up to 144 days. High titers may indicate recent exposure, and viral shedding may be occurring within the sampled population.  

The most frequently used diagnostic tests are an ELISA and an indirect fluorescent antibody test. In order for meaningful results to be generated, serum should be collected from around 20 exposed animals in the herds.  Both of the ELISA and the IFAT tests measure antibodies against PRRS virus. Anti-PRRS specific IgM can be detected within 7 days of infection, and IgG can be detected within 14 days. Titres peak about 5–6 weeks after infection, and can persist for up to 144 days while circulating virus is present. Once virus ceases to circulate, antibody levels quickly drop. If titres are particularly high, exposure may be recent exposure and the sampled population could currently be shedding virus.

Tests for the PRRS virus itself also exist. These include PCR and virus isolation on clinical samples, and immunohistochemistry on tissues. Nucleic acid sequencing of the 5' end of the virus is commercially availabe ans is useful for comparing isolates recovered from different sites in order to facilitate epidemiological investigations.

Tests for the PRRS virus itself also exist. These include PCR and virus isolation on clinical samples, and immunohistochemistry on tissues. Nucleic acid sequencing of the 5' end of the virus is commercially availabe ans is useful for comparing isolates recovered from different sites in order to facilitate epidemiological investigations.

and tonsils of affected animals. Samples from mummified or aborted litters are unlikely to yield virus, but can

and tonsils of affected animals. Samples from mummified or aborted litters are unlikely to yield virus, but can

still be useful for RT-PCR.

still be useful for RT-PCR.

􀂃 Virus isolation

􀂃 Virus isolation

Buffy coat, serum, lung, lymph nodes, spleen and tonsils are the specimens of choice. The virus

Buffy coat, serum, lung, lymph nodes, spleen and tonsils are the specimens of choice. The virus

time, there is no fully validated PCR that has international acceptability. Please consult the OIE

time, there is no fully validated PCR that has international acceptability. Please consult the OIE

Manual for suggested methods.

Manual for suggested methods.

==Pathology==

==Pathology==