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Infectious bovine keratoconjunctivitis: a review
M H Brown1, A H Brightman, B W Fenwick
1Veterinary Referral Centre, Little Falls, NJ 07424, USA. Muro128@aol.com
Abstract:
The economic impact of infectious bovine keratoconjunctivitis (IBK) warrants continued investigation of the mechanisms by which Moraxella bovis 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, season, and concurrent infection influence the prevalence of IBK. Mycoplasma sp. or infectious bovine rhinotracheitis virus may enhance or hasten the disease process. The manifestations of IBK may range from mild conjunctivitis to severe ulceration, corneal perforation, and blindness. Treatment of IBK is dictated by economic considerations, intended animal use, and feasibility of administration. Antibiotic therapy is aimed at achieving drug concentrations in tears to meet or exceed the minimum 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 must be identified and removed from the herd. Vaccination trials have been unsuccessful because of pili antigen cross-reactivity, variable strains, and uncontrolled environmental factors. Recent investigations have determined that M bovis may utilize host iron sources via iron-repressible outer membrane proteins and siderophores for growth. Elucidation of normal defense mechanisms of the bovine eye may lead to new strategies to enhance the immune response against M bovis.
Insights
Infectious bovine keratoconjunctivitis (IBK) impacts cattle economics. Understanding Moraxella bovis survival mechanisms is key to managing this costly eye disease in cattle.
Area of Science:
- Veterinary Ophthalmology
- Bacterial Pathogenesis
- Animal Infectious Diseases
Background:
- Infectious bovine keratoconjunctivitis (IBK) causes significant economic losses in cattle.
- Moraxella bovis is the primary bacterial agent responsible for IBK.
- Virulent M. bovis strains possess hemolysin and distinct plasmid profiles.
Purpose of the Study:
- Investigate M. bovis survival and colonization mechanisms on the bovine cornea.
- Identify factors influencing IBK prevalence, including host, environment, and coinfections.
- Explore potential new strategies for immune response enhancement against M. bovis.
Main Methods:
- Review of existing literature on IBK pathogenesis and M. bovis virulence factors.
- Analysis of factors affecting disease transmission and manifestation.
- Examination of M. bovis iron acquisition strategies.
Main Results:
- IBK severity ranges from mild conjunctivitis to blindness.
- Coinfections with Mycoplasma sp. or BHV-1 can exacerbate IBK.
- M. bovis utilizes host iron via specific outer membrane proteins and siderophores.
Conclusions:
- Effective IBK management requires understanding M. bovis virulence and host-pathogen interactions.
- Current prevention strategies are limited; control relies on herd management and vector control.
- Further research into bovine ocular defense mechanisms may reveal novel therapeutic targets.