Glanders

Description

Caused by Burkholderia (Pseudomonas) mallei

Signalment

Equidae are most commonly affected, horses tend to get the chronic form and mules and donkeys the acute form. The disease was once widespread in the UK but was eradicated in 1928 and is now a Notifiable disease. Distribution is limited to parts of SE Asia, The Middle East, India, North Africa, China and Mongolia.

References

• Characterised by multiple small submucosal nasal nodules which liquefy and ulcerate
  • Cores of neutrophils surrounded by a rim of macrophages and granulation tissue
• In addition may have similar nodules in lungs, lymph nodes and cutaneous lymphatics
• Clinical signs: fever and head/ neck lymphadenitis, rhinitis

• Pathogenesis:
  • Transmited by ingestion of food/water contaminated by nasal discharge of infected Equidae; occasionally via inhalation or skin wounds
  • Organism invades nasopharyngeal mucosa and spreads to other tissues via lymphatics
  • Presence of B. mallei in host causes hypersensitivity reaction
• Clinical infections:
  • Acute septicaemic form with fever, mucopurulent nasal discharge and respiratory signs; death within weeks
  • Chronic disease more common:
    • Nasal form: rhinitis; ulcerative nodules develop on mucosa of nasal septum and lower part of turbinates; purulent blood-stained nasal discharge; regional lymphadenitis
    • Respiratory form: respiratory distress; granulomatous lesions throughout lungs
    • Cutaneous form (farcy): lymphangitis; nodules along lymphatic vesselsof limbs; ulcers develop and discharge pus
    • May die after several months or recover and shed organisms from respiratory tract or skin
  • Carnivores may contract disease by eating infected carcasses
• Diagnosis:
  • Specimens include discharges from lesions and blood for serology
  • Grows on media containing 1% glycerol; most strains are non-lactose fermenters on MacConkey agar
  • Complement fixation and agglutination
  • Serology
  • Mallein test: mallein injected intradermally below lower eyelid; local swelling and discharge indicates positive reation
• Treatment/control:
  • Test and slaughter policy where disease exotic
  • Disinfection of contaminated areas using formalin or an iodophor