INFECTIOUS BOVINE KERATOCONJUNCTIVITIS - A REVIEW

The economic impact of infectious bovine keratoconjunctivitis (IBK) wa rrants continued investigation of the mechanisms by which Moraxella bo vis survives on and colonizes the corneal surface. Virulent strains of M bovis produce hemolysin and exhibit different plasmid profiles than nonvirulent strains. Interactions among host, environment, vector, se ason, and concurrent infection influence the prevalence of IBK. Mycopl asma sp. or infectious bovine rhinotracheitis virus may enhance or has ten the disease process. The manifestations of IBK may range from mild conjunctivitis to severe ulceration, corneal perforation, and blindne ss. Treatment of IBK is dictated by economic considerations, intended animal use, and feasibility of administration. Antibiotic therapy is a imed at achieving drug concentrations in tears to meet or exceed the m inimum inhibitory concentration for prolonged periods. At present, IBK is not a preventable disease. Affected animals must be separated from the herd and vector control vigorously instituted. Carrier animals mu st be identified and removed from the herd. Vaccination trials have be en unsuccessful because of pill antigen crossreactivity, variable stra ins, and uncontrolled environmental factors. Recent investigations hav e determined that M bovis may utilize host iron sources via iron-repre ssible outer membrane proteins and siderophores for growth. Elucidatio n of normal defense mechanisms of the bovine eye may lead to new strat egies to enhance the immune response against M bovis.