Student Case Presentation
A Case-Control Study to Evaluate Differences in Pathogen Load and Moraxella bovis Serum Antibody Level on the incidence of Infectious Bovine Keratoconjunctivitis (IBK) in Suckling Beef Calves
| Date/Time: |
9/12/2024 2:15 pm
|
| Presenter: |
Adri Scholten Tilstra |
| Veterinary School: |
IA |
Abstract:
Infectious Bovine Keratoconjunctivitis (IBK) is a common disease affecting cattle across the US. Various prevention and control strategies have mixed results and a better understanding of the causality of clinical IBK is needed. The objectives of this case-control study were to: 1) evaluate differences in pathogens identified in the eyes of calves diagnosed with clinical IBK vs. normal calves, 2) determine the effect of clinical IBK on calf growth, and 3) utilize ELISA testing to determine differences in serum antibody to Moraxella bovis between these groups. A total of 163 spring-born Angus calves (84 clinical; 79 normal) were utilized for this case-control study. Serum was collected from calves at grass turn-out, mid-summer, and weaning, for detection of IgG specific to Type IV pilus protein (pilA) of Moraxella bovis using ELISA. Paired ocular swabs from clinical and control cases were sampled and analyzed with PCR and culture with MALDI-TOF identification to determine the presence of pathogens associated with IBK. To assess differences between clinical and control calves, chi-squared statistics, ANOVA, and a repeated measures model were utilized with P values < 0.05 considered significant. All samples were negative for IBR and Mycoplasma bovis and calf growth was not affected by IBK status. Clinical cases of IBK had significantly lower Ct values for Moraxella bovis and Moraxella bovoculi (p<0.0001). Clinical animals had a 9.37 higher risk of being culture positive for Moraxella bovis and/or Moraxella bovoculi. ELISA titers for Moraxella bovis increased significantly over the course of the study, but there was no difference between clinical and control calves at any time point. In conclusion, there were differences in pathogen load between groups, but serum antibody levels did not influence disease state. This indicates the need for improved vaccine options and control strategies for IBK focused on Moraxella spp.
