Detection of early "significant" antibody responses in paired sera by the use of an automated bovine parainfluenza-3 hemagglutination-inhibition system.

An automated bovine parainfluenza-3 hemagglutination-inhibition system was used to detect small increases (15--20%) in specific antibody titer between paired bovine sera collected three days apart. Automated and manual parainfluenza-3 hemagglutination-inhibition test procedures were compared as methods for the serologic diagnosis of parainfluenza-3 infection. Fifteen daily serum specimens from each of three animals were analyzed as various possible manual-test and automated-test serum pairs. With the sera from two of the animals, considered to be parainfluenza-3 hemagglutination-inhibition-positive, the manual microtiter test procedure made 18 (69%) false negative diagnoses when using the standard manual-test criteria for "evidence of infection." When a 20% titer increase between three-day serum pairs was considered "serologically significant," the automated system made three (17%) false-negative diagnoses. At a 15% "serologically significant" increase, no false-negative diagnosis was made. The utilization of automated serology for the routine diagnosis of disease should permit treatment and control measures to be initiated early, thereby reducing losses due to infectious disease.