Serologic reactions against Salmonella in samples from broiler parent stock with and without preceding colibacillosis: A case-control study

K.O. Gradel, Niels Christian Feld, J. S. Andersen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    In the Danish Salmonella Control Program, eggs from broiler parent flocks are surveyed by serologic analysis every 4 wk for antibodies against Salmonella lipopolysaccharide O-antigens 1, 4, 5, 9, and 12 (Mix-enzyme-linked immunosorbent assay [ELISA]) and 6 and 7 (Infantis-ELISA). The antibody response is measured in percentage optical density (OD%) of a strong positive reaction, and the cutoff value has been determined to be 40 OD%. Two or more reactors above 40 OD% will place the parent flock under suspicion. There has been concern about possible cross-reactions between Salmonella spp. and other Enterobacteriaceae, e.g., Escherichia coli, because a high specificity of a Salmonella antibody test is desirable. Moreover, false-positive Salmonella results have economic consequences and impede planning the production. A case-control study based on cases of clinical E. coli infections (colibacillosis) from two Danish hatcheries, supplying about 62% of the Danish broiler production, is described. In order to eliminate a possible bias from age and season, the controls were matched on age of the birds and on time of submitting the samples. This study shows that flocks with preceding colibacillosis did nor have higher salmonella reactions than matched flocks without a preceding colibacillosis. This observation was confirmed in longitudinal studies.
    Original languageEnglish
    JournalAvian Diseases
    Volume45
    Issue number2
    Pages (from-to)486-491
    ISSN0005-2086
    Publication statusPublished - 2001

    Keywords

    • cross-reactions
    • colibacillosis
    • Salmonella serology
    • case-control study

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