920 bytes added ,  17:28, 26 May 2008
no edit summary
Line 24: Line 24:     
*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  
+
*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
 +
 
 +
 
     
462

edits