title: Descriptive epidemiology of Moraxella bovis, Moraxella bovoculi and Moraxella ovis in beef calves with naturally occurring infectious bovine keratoconjunctivitis (Pinkeye).
abstract: OBJECTIVE
  Infectious bovine keratoconjunctivitis (IBK) is an ocular disease that causes substantial weight loss in beef calves.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the association between Moraxella bovoculi, Moraxella bovis and Moraxella ovis and IBK incidence.
  
  
  METHODS
  A cohort design was used. From 239 calves and 478 eyes, 77 randomly chosen eyes were monitored for M. bovoculi, M. bovis, M. ovis and IBK incidence over 4 months. One hypothesis tested was that IBK hazard in eyes was not associated with detection of M. bovoculi, M. bovis and M. ovis. A secondary hypothesis tested that IBK cases were not associated with increased prevalence of M. bovoculi, M. bovis and M. ovis.
  
  
  RESULTS
  23% of 77 eyes developed IBK. M. ovis was identified in one IBK-negative eye. The adjusted hazard ratio (HR) for IBK incidence from eyes where M. bovoculi or M. bovis were recovered prior to disease occurrence were not statistically significant (M. bovoculi HR=1.38, 95% CI: 0.54-3.53, p=0.49, M. bovis HR=1.60, 95% CI: 0.48-5.53, p=0.44). The adjusted hazard ratio for M. bovoculi in IBK lesions was 6.45 (95% CI: 3.35-12.44, p<0.001). The adjusted hazard ratio for M. bovis in IBK lesions was 2.33 (95% CI: 1.22-4.45, p=0.01).
  
  
  CONCLUSIONS
  A temporal association between prior exposure to M. bovoculi or M. bovis and subsequent IBK incidence was not demonstrated. However, M. bovoculi and M. bovis are more frequently recovered from eyes with IBK lesions than unaffected eyes and this provides weak evidence for a causal role.
authors.affiliation: Department of Veterinary Diagnostics and Production Animal Medicine, Iowa State University College of Veterinary Medicine, 1600 S. 16th St, Ames, IA 50011, USA. oconnor@iastate.edu
authors.forename: A M
authors.initials: AM
authors.lastname: O'Connor
authors.forename: H G
authors.initials: HG
authors.lastname: Shen
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Opriessnig
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D015331:Cohort Studies; D003234:Conjunctivitis, Bacterial / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005123:Eye / Q000382:microbiology; D007639:Keratoconjunctivitis, Infectious / Q000453:epidemiology / Q000382:microbiology*; D009016:Moraxella / Q000302:isolation & purification*; D016955:Moraxella bovis / Q000302:isolation & purification*; D045828:Moraxellaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*