Evaluation of an immunofluorescent test for the rapid diagnosis of field infections of infectious bovine rhinotracheitis.

An indirect immunofluorescent test for the rapid detection of infectious bovine rhinotracheitis (IBR) virus in smears of nasal and ocular secretions from infected cattle, was compared with conventional virus isolation procedures using 200 swabs from 107 field outbreaks of suspected IBR. Virus was isolated from 38 per cent of the swabs and the indirect immunofluorescent test detected virus in 14.5 per cent of the positive swabs. Examination of samples from more than one animal increased the confirmation rates of infection during outbreaks to 39 per cent by virus isolation and 21.5 per cent by the immunofluorescent test. Ocular swabs were better than nasal swabs for confirming infection both by virus isolation and immunofluorescence, and agreement between the two tests increased with the number of samples collected during an outbreak.