The serology of experimental Salmonella dublin infections of cattle

Abstract

Agglutinating antibodies to somatic "O" and flagellar "H" antigens of S. dublin were measured in the serum of 43 pregnant heifers before intravenous or oral infection with S. dublin and in the serum of 21 uninfected control animals. The data from these animals were analysed statistically and a titre of 1/80, to both antigens, has been interpreted as of doubtful significance and a titre of 1/160 to both antigens, has been interpreted as significantly raised. Animals in which fetal infection occurred after challenge by either the intravenous or oral route developed significant increases in "H" and "O" titres indicating the value of measure "H" titres in the diagnosis of S. dublin abortion. In animals which were infected orally and in which infection appeared to be confined to the alimentary tract the "H" titre did not become significantly raised. Lack of correlation between antibody titres and faecal excretion of S. dublin and persistence of infection in carcasses confirms that the serum agglutination test is of no value in detecting latent carriers.

Sensitivity, specificity and predictive probability values of serum agglutination test titres for the diagnosis ofSalmonellaDublin culture-positive bovine abortion and stillbirth

“…Unlike enteric salmonellosis, the flagellar H antigen titre in S . Dublin abortion may reach as high a value as the somatic O antigen titre (Hall, Jones, Aitken, & Parsons, ; Veling, van Zijderveld, van Zijderveld‐van Bemmel, Barkema, & Schukken, ). While the flagellar antigen titre is considered to be marginally superior to the somatic antigen titre for diagnosis of S .…”

“…Dublin abortion, it has been emphasized that both titres should always be determined (Hinton, ). Result classification breakpoints proposed for both, somatic and flagellar titres, differ between studies (Hall et al., ; Hinton, ,b) with those currently (2017) used by the Irish regional veterinary laboratories (RVLs) being an O titre of ≥1/80 or an H titre of ≥1/320 (Hinton, ). Other studies using somatic O and flagellar H antigens set cut‐offs for positive results at dilutions of ≥1/80 or 1/160 (Hall et al., ; Veling et al., ).…”

“…Result classification breakpoints proposed for both, somatic and flagellar titres, differ between studies (Hall et al., ; Hinton, ,b) with those currently (2017) used by the Irish regional veterinary laboratories (RVLs) being an O titre of ≥1/80 or an H titre of ≥1/320 (Hinton, ). Other studies using somatic O and flagellar H antigens set cut‐offs for positive results at dilutions of ≥1/80 or 1/160 (Hall et al., ; Veling et al., ). A further complication is that some authors consider a blood sample to be positive if either the somatic O or flagellar H antigen exceeds the cut‐off value while others require both to exceed the designated threshold; otherwise, the result is deemed inconclusive.…”

“…Dublin abortion, the first taken around the time of the abortion and the second 2–3 weeks later (Hinton, ). Limited data suggest that an improvement in diagnostic sensitivity (Se) can be achieved if the first blood sample is taken more than 4 days after the abortion has occurred (Hall et al., ; Veling et al., ). Salmonella Dublin abortion should be suspected where there is a significant increase in titres between the first and second samples, where both samples show elevated titres above a cut‐off level (diagnostic titres), or where they decline from a significantly high titre to a lower titre (Hinton, ).…”

“…Salmonella Dublin abortion should be suspected where there is a significant increase in titres between the first and second samples, where both samples show elevated titres above a cut‐off level (diagnostic titres), or where they decline from a significantly high titre to a lower titre (Hinton, ). Titres eventually fall below cut‐off levels at about 10 weeks post‐abortion (Hall et al., ).…”