Infectious bovine keratoconjunctivitis: effects of vaccination on Moraxella bovis carrier state in cattle
Pugh, G.W.; McDonald, T.J.; Kopecky, K.E.
American Journal of Veterinary Research 41(2): 264-266
1980
ISSN/ISBN: 0002-9645 PMID: 7369598 Document Number: 161656
Virulent culture of Moraxella bovis (M.b.) was instilled into the eyes of 14 calves. Twenty days later, when the calves were showing signs of IBK, seven calves were vaccinated with M.b. pilus vaccine made from the exposure strain. Ocular and nasal discharges were collected and examined for 64 days. Most calves developed signs of IBK after exposure, and all but one calf (unvaccinated) developed ocular M.b. infection. The mean number of days of ocular infection was practically the same in vaccinated and unvaccinated calves. The eyes of the calf that did not become infected with M.b. were infected with a pure culture of Escherichia coli. This calf failed to develop ocular infection, but M.b. was present in its nasal discharge throughout the study (64 days). M.b. was isolated from the nasal discharge of other calves only when there were concurrent ocular infections.