SEROLOGICAL DETECTION OF CHICKEN FLOCKS NATURALLY INFECTED WITH SALMONELLA-ENTERITIDIS, USING AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY BASED ONMONOCLONAL-ANTIBODIES AGAINST THE FLAGELLAR ANTIGEN

The Dutch Salmonella enteritidis monitoring and eradication programme for poultry prescribes a periodic examination of all breeding flocks f or the presence of S. enteritidis. For the first years of the programm e this was done by bacteriological examination of 50 faecal samples pe r visit per flock. In this study we compare the results of bacteriolog ical examination of faecal samples taken at 1580 visits from 545 flock s with those of a S. enteritidis enzyme-linked immunosorbent assay (EL ISA) applied on 24 serum samples per visit per flock. Two flocks were found positive for S. enteritidis by bacteriological examination; both flocks were also detected by ELISA. Ten flocks, bacteriologically neg ative for S. enteritidis were found positive by ELISA. S. enteritidis was isolated from three of these flocks by repeated and extensive bact eriological examination for verification. Verification was not possibl e in the fourth ELISA positive flock. S. enteritidis infections were l ikely in three other flocks because of the farm histories. On the basi s of the results of this study it was decided to use this ELISA, start ing from April 1992, as screening technique in the Dutch S. enteritidi s programme instead of bacteriological examination of faecal samples. The ELISA is regarded as a flock test; an extensive, confirmatory bact eriological investigation for S. enteritidis is carried out in ELISA p ositive flocks to decide whether the flocks are truly infected.