Monitoring the prevalence of Lawsonia intracellularis IgG antibodies using serial sampling in growing and breeding swine herds
Marsteller TA, Armbruster G, Bane DP, et al
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Objective: To determine seroprevalence of Lawsonia intracellularis and the time of seroconversion in growing and breeding swine herds using the immunoperoxidase monolayer assay (IPMA).
Methods: Blood was collected from individually identified growing pigs in 16 herds at weaning (approximately 3 weeks of age) and in those herds, plus four others, at 3-week intervals until market weight (total 20 herds). Blood was collected from individually identified breeding animals (replacement gilts) at entry into nine breeding herds and then at 3-week intervals. Samples were tested at a dilution of 1:30 using the IPMA, which identifies IgG antibodies.
Results: Fifteen of twenty growing herds (75%) were seropositive for L intracellu-laris at some time between weaning and 24 weeks of age. Within-herd seroprevalence in positive growing herds ranged from 11 to 92% and peaked near marketing (18 to 24 weeks of age). Seven of nine breeding herds (78%) were seropositive. Within-herd seroprevalence in breeding herds ranged from 5 to 61% and peaked near the time of herd entry and again late in the study.
Implications: As L intracellularis IgG serum antibodies were short-lived in this study, serial blood sampling at intervals of 3 weeks or less may prove useful in determining L intracellularis serological status in a swine production system. On the basis of these results, blood samples to detect exposure to L intracellularis should be collected from growing swine at 18 to 24 weeks of age, and from replacement gilts at entry into the breeding herd and at first lactation.
Keywords: Lawsonia intracellularis, immunoperoxidase monolayer assay, porcine proliferative enteritis, serology
Cite as: Marsteller TA, Armbruster G, Bane DP, et al. Monitoring the prevalence of Lawsonia intracellularis IgG antibodies using serial sampling in growing and breeding swine herds. J Swine Health Prod 2003;11(3):127-130.
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