DIFFERENTIAL SENSITIVITY OF CULTURE AND THE POLYMERASE CHAIN-REACTIONFOR DETECTION OF FELINE HERPESVIRUS-1 IN VACCINATED AND UNVACCINATED CATS

The diagnostic sensitivities of the polymerase chain reaction (PCR) an d culture were compared and correlated with clinical signs in 5 vaccin ated cats and 3 unvaccinated cats that were experimentally infected wi th feline herpesvirus 1. Conjunctival swabs were taken each day from 0 to 14 days and on 21, 28 and 30 days after challenge. PCR (49.3%) was significantly more sensitive than culture (30.1%) as assessed by an a djusted McNemar's test to account for non-independence of results betw een days within each cat (P = 0.02). PCR was considerably more sensiti ve (34.1%) than culture (8.2%) in vaccinated cats (P = 0.001), whereas there was no significant difference in sensitivities in the unvaccina ted cats, where the sensitivity of PCR was 74.5% and that of culture w as 66.7% (P = 0.17). In vaccinated cats showing clinical signs, the se nsitivities of culture and PCR were 14.8% and 55.6% respectively (P = 0.03), whereas in unvaccinated cats the sensitivities were 80.6% and 9 6.8% respectively (P = 0.07). This study suggests that disease due to feline herpesvirus 1 has been significantly underdiagnosed, particular ly in vaccinated cats.