Not usually used as a diagnostic sample but may be useful
for the detection of carrier animals.
The site of virus persistence in carrier animals is the
pharynx and cranial oesophagus.
Samples of fluid and cellular material can be collected
from this region using a specially shaped 'probang cup' attached to a
wire handle.
The titre of the virus in the pharyngeal fluid is usually
low, so the material must be mixed immediately with an equal volume of
buffered tissue culture fluid at pH 7.4 and submitted to the reference
laboratory following an agreed protocol (usually frozen on dry ice).
