Clinical cases are diagnosed based on the presence of clinical signs
serological test. A seropositive test by
itself has limited
since there is a high incidence of seropositivity in many flocks,
in older animals. A positive test does indicate that the animal is
infected, but does not indicate that signs or lesions are attributable
infection with the virus.With serological tests, one should keep in
mind that the
slow development of antibodies following infection must be considered
interpretation of a negative result (source 2).
confirmation of diagnosis:
Virology – lung, mammary gland, synovial membrane, brain
Serology – heart blood
serum (ELISA, AGID)
Histology – formalin
fixed lung, bronchial lymph
mammary gland, synovial membrane, half of the mid-sagitally sectioned
Physical exam: see clinical
· Enzyme Linked
Immunosorbatant Assay (ELISA):
hypochromic anemia may be observed with hemoglobin levels falling from
12-14 g/dl to 7-8 g/dl.
is seen in advanced cases.
- There is an early leukocytosis following exposure, but the count
returns to normal when clinical signs appear.
Agar Gel Immunodiffusion (AGID):
- Used to detect a recombinant transmembrane envelope protein
economical than whole-virus ELISA or Western Blot
- More sensitive than AGID
sensitive than ELISA
economical and sensitive way to detect viral nucleic acids than viral
For eradication of the
disease from a herd, it is
recommended to use both AGID and PCR and to repeat the tests two or
several months (source 1).