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| − | {{toplink
| + | #redirect[[Infectious Bovine Keratoconjunctivitis]] |
| − | |backcolour =
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| − | |linkpage =Bacteria
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| − | |linktext =BACTERIA
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| − | |pagetype=Bugs
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| − | }}
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| − | <br>
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| − | ===Overview===
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| − | *''Moraxella bovis'' causes infectious bovine keratoconjunctivitis
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| − | *Found on mucous membranes of carrier cattle
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| − | *Susceptible to desiccation therefore short survival in environment
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| − | *Flies act as vectors, in which the bacteria can survive 72 hours
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| − | *Other species non-pathogenic
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| − | | + | [[Category:Bacteria miscellaneous]] [[Category:Rods]] [[Category:Cocci]] [[Category:Cattle Bacteria]] |
| − | ===Characteristics===
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| − | *Short, plump Gram negative rods or cocci occuring in pairs
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| − | *Non-motile
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| − | *Aerobic
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| − | *Catalase positive, oxidase postitive
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| − | *Unable to utilise sugars
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| − | *No growth on MacConkey agar
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| − | *Growth enhanced by addition of blood or serum to media
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| − | | |
| − | ===Pathogenesis and pathogenicity===
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| − | *Virulent strains have fimbriae, are haemolytic and grow into agar
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| − | *Fimbriae allow adherence to the cornea
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| − | *Q fimbriae are specific for colonisation; I fimbriae allow local persistence of infection
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| − | *Fimbrial antigens stimulate immunity
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| − | *Haemolysin, fibrinolysin, phosphatase, hyaluronidase and aminopeptidase as well as LPS contribute to virulence
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| − | *Haemolysin damages neutrophil membranes; release of hydrolytic enzymes from these neutrophils damages the corneal surface
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| − | *Isolates from carrier animals often avirulent, and are non-haemolytic and have no fimbriae; reversion to virulence can occur
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| − | ===Clnical infections===
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| − | *Infectious bovine keratoconjunctivitis, or pink-eye/New Forest disease is an ocular disease of cattle
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| − | *Highly contagious infection of superficial tissues of eye
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| − | *Affects animals under 2 years old
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| − | *Decreased weight gain in beef cattle, decreased milk production in dairy herds
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| − | *Age-related immunity due to previous exposure
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| − | *Antibodies against haemolysin neutralise different strains, whereas antibodies to fimbriae are strain-specific
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| − | *Asymptomatic carrier animals harbour the bacteria in the nasolacrimal ducts, nasopharynx and vagina
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| − | *Transmission by direct contact, aerosol and via flies
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| − | *Clinical signs: blepharospasm, conjunctivitis, lacrimation
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| − | *Keratitis and corneal ulceration, opacity and abscessation may lead to panophthalmitis and permanent blindness
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| − | *Stromal oedema; coning of cornea
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| − | *Cornea may heal or undergo permanent scarring
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| − | ===Diagnosis===
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| − | *Swabs of lacrimal secretions
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| − | *Fluorescent antibody test demonstrate presence of ''M. bovis''
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| − | *Culture on blood agar; colonies are round, small, shiny and friable
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| − | *Virulent strains surrounded by complete haemolysis and are embedded in the agar
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| − | *No growth on MacConkey
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| − | *Autoagglutination in saline
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| − | *Short Gram negative rods on smears
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| − | *7 serotypes based on fimbriae
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| − | ===Treatment and control===
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| − | *Subconjunctival or topical antimicrobials
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| − | *Isolate animals
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| − | *Reduce mechanical irritation such as dust, grass, grass seeds
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| − | *Insect control
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| − | *Control concurrent infections
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| − | *Prophylactic oxytetracycline for animals at risk
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| − | *Vitamin A supplementation
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