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*Virulent strains have fimbriae, are haemolytic and grow into agar
*Virulent strains have fimbriae, are haemolytic and grow into agar
*Fimbriae allow adherence to the cornea
*Q fimbriae are specific for colonisation; I fimbriae allow local persistence of infection
*Fimbrial antigens stimulate immunity
*Haemolysin, fibrinolysin, phosphatase, hyaluronidase and aminopeptidase as well as LPS contribute to virulence
*Haemolysin damages neutrophil membranes; release of hydrolytic enzymes from these neutrophils damages the corneal surface
*Isolates from carrier animals often avirulent, and are non-haemolytic and have no fimbriae; reversion to virulence can occur
===Clnical infections===
===Clnical infections===
*Infectious bovine keratoconjunctivitis, or pink-eye/New Forest disease is an ocular disease of cattle
*Highly contagious infection of superficial tissues of eye
*Highly contagious infection of superficial tissues of eye
*Affects animals under 2 years old
*Affects animals under 2 years old
*Decreased weight gain in beef cattle, decreased milk production
*Decreased weight gain in beef cattle, decreased milk production in dairy herds
*
*Age-related immunity due to previous exposure
*Asymptomatic carrier animals harbour the bacteria in the nasolacrimal ducts, nasopharynx and vagina
*Transmission by direct contact, aerosol and via flies
*Clinical signs: blepharospasm, conjunctivitis, lacrimation
*Keratitis and corneal ulceration, opacity and abscessation may lead to panophthalmitis and permanent blindness