Haemophilus species

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Haemophilus characteristica

  • Morphologically variable Gram-negative bacilli, ranging from short rods to long filaments
  • Oxidase negative
  • Depend on beta-nicotinamide adenine dinucleotide (NAD) and/or Haemin for growth
  • Heated blood agar (Chocolate Agar) required for growth of NAD-dependent strains
  • Haemin-dependent strains grow on Blood Agar
  • Do not grow on MacConkey agar
  • Inhabit mucosal epithelium of respiratory and genital tract


Haemophilus parasuis

  • Serotype B causes Glasser's disease in pigs
  • Glasser's disease
    • Due to transport, environmental stresses, dietary and managemental factors
    • Acute septicaemia
    • Causes a polyserositis - pericarditis, peritonitis, pleurisy and meningitis - in pigs 3-10 weeks old
    • Sporadic outbreaks in the UK
    • Can be fatal in 2-5 days
    • Mortality up to 50% insome outbreaks
    • Chronic arthritis, meningitis and intestinal obstruction due to adhesions in surviving pigs

peritonitis, suppurative bronchopneumonia, pleuritis, pericarditis, (as part of polyserositis), meningitis, polyarthritis (also H. suis)

    • Expressed lesion vary between animals - meningitis is most consistent, arthritis in 20% of cases
  • Fibrinous pneumonia secondary to enzootic pneumonia or virus infection


Haemophilus somnus

  • Causes infectious thromboencephalitis in cattle 1-3 years old
  • Found in the USA and Europe, including UK
  • Causes a meningoencephalitis with fibrinous arterial thrombosis and necrosis
  • Causes fever, staggering and dyspnoea, progressing to somnolence, paralysis and death
  • Mortality can be high


Haemophilus paragalinarum

  • Conjunctivitis in poultry


Haemophilus influenzae

  • Human respiratory disease