Glanders Disease Explained | Etiology, Pathogenesis, Diagnosis & Control | BVSc | ICAR-PG | VO Exams

Main ideas / concepts covered

1) What glanders is

• Glanders is a contagious, very serious disease of horses, mules, and donkeys.
• Causative agent (bacterium): Pseudomonas malayi
  • Formerly known as: Actinomyces malayi and Malliomyces malayi
• Forms of disease:
  • Acute
  • Chronic
• Primary affected sites:
  • Respiratory tract
  • Skin
  • Lesions include nodules and ulcers
• Severity / outcome:
  • Disease is usually fatal in animals.
  • Humans are also susceptible and it is often fatal.

2) Organism description and survival

• Morphology: cylindrical, Gram-negative rod
• Size: about 1.5–5 µm long and 0.3–0.5 µm broad
• Motility: non-motile
• Spores/capsule: does not form spores and is non-capsulated
• Sensitivity: easily destroyed by disinfectants such as:
  • Hypochlorite
  • Iodine
  • Mercuric chloride
• Survival in environments:
  • ~20 days in clean water
  • ~6 weeks in stable environments

3) Geographic distribution (as stated)

Found mainly in:

• Eastern Europe
• Asia Minor
• Asia
• North Africa

4) Transmission and pathogenesis (step-by-step)

• Main routes of infection:

  • Ingestion of contaminated food or water
  • Inhalation (organism enters via the respiratory route)

• Within the body:

  1. Organism reaches the intestine
  2. Spreads into the blood → bacteremia/septicemia
  3. Settles in:
     • Nasal mucosa
     • Lower parts of nasal turbinates
     • Lungs
     • Skin (especially around hyoid limbs, per subtitle)
  4. Causes lesion development:
     • Nodules in nasal cavity and skin → ulcerate
     • Lesions may coalesce into large ulcers

• Lymphatic involvement (key signs):

  • Lymph nodes and lymph vessels become inflamed
  • Swollen lymph nodes may burst and discharge dark honey-like pus
    • Called “Persian buds”
  • Thickened, cord-like lymph vessels
    • Called “Persian cords”
  • Lymph tissue becomes very swollen → elephantiasis-like appearance
  • Cutaneous form referred to as “Persian” (as described)

5) Differences between acute and chronic glanders (clinical/pathology)

Acute form

• Common in: mules and donkeys
• Signs:
  • High fever
  • Cough
  • Nasal discharge
  • Nodules/ulcers on skin and nasal mucosa
• Course/outcome:
  • Septicemia can cause death within a few days
• Postmortem/necropsy findings:
  • Multiple hemorrhages throughout the body
  • Bronchopneumonia
  • Enlargement of bronchial lymph nodes

Chronic form

• Most commonly seen in: horses
• Signs:
  • Long-standing cough
  • Frequent epistaxis (nosebleeds)
  • Labored respiration
  • Gradual development of nodules/ulcers on:
    • Skin
    • Nasal cavity
    • Limbs
  • Nasal discharge:
    • Initially serous
    • Later purulent and blood-tinged
  • Submaxillary lymph nodes swollen
  • May last a few months
• Postmortem/necropsy findings:
  • Miliary nodules throughout lung area
  • Ulcers in upper respiratory tract
  • Nodules/ulcers in skin and subcutis of limbs → leads to enlarged limbs

6) Diagnosis (including tests and interpretation)

Clinical suspicion

Suspect glanders in horses showing:

• High fever
• Cough
• Nasal lesions
• Persian buds
• Persian cords

Primary/most important test: Mallein (allergic test)

• Mallein: antigen prepared from Pseudomonas malayi
• Types mentioned:
  • Subcutaneous
  • Ophthalmic
  • Intradermal
  • Intradermopalpebral (as written)
• Most commonly used: Intradermal palpable test
  • Procedure (as described):
    • Inject 0.1 ml of solution into the skin of the lower eyelid
    • Use a tuberculin syringe
  • Reading time: check after 48 hours
  • Positive result criteria:
    • Marked eyelid edema
    • Blepharospasm
    • Severe purulent conjunctivitis

Serological tests

• Useful for diagnosis.
• Most reliable (as stated): Complement fixation test
• Other tests mentioned:
  • Indirect hemagglutination test
  • Conglutinant complement absorption test
  • Dot ELISA developed for field use

Confirmatory test: Strauss reaction

• Method:
  • Inject pus from the suspected animal into the intraperitoneal cavity of a male guinea pig
• Positive result:
  • Guinea pig develops severe orchitis
  • And inflammation of the scrotal sac
  • → confirms glanders

7) Differential diagnosis (diseases that resemble glanders)

Need to distinguish glanders from diseases with similar signs, especially with:

• Nodules
• Ulcers
• Lymph vessel involvement

Look-alikes mentioned:

• Episodic lymphangitis caused by Histoplasma phaeosporinosis
• Ulcerative lymphangitis caused by Corynebacterium pseudoculosis
• Sporotrichosis caused by Sporotrichum senkai and severe triangles (wording as provided)

How to differentiate (as stated):

• Isolate and identify the organism in the laboratory, OR
• Use the mallein/Müller test that is specific for glanders (as written)

8) Treatment and legal control

• Treatment is usually not advised
  • Reason: disease can easily spread to humans and is dangerous
• Legal requirement:
  • Under Glanders and Far(s) Act (as written), affected animals must be legally euthanized
• If treatment is absolutely necessary (per subtitle):
  • Sulfadimidine for about 20 days is described as highly effective

9) Prevention and control measures (structured)

• Quarantine
  • Apply strict quarantine measures:
    • In disease-affected areas
    • Also when importing horses from other areas/countries
• Culling
  • Horses testing positive should be destroyed per Glanders and Horses Act of India
• Testing of at-risk animals
  • All horses, mules, and donkeys in affected areas should be tested repeatedly every three weeks
  • Using the mallein test
  • Continue until all reactors are identified and removed
• Disinfection
  • Implement a strong, thorough disinfection program for:
    • Areas
    • Stables
    • Equipment
  • Goal: completely eliminate the organism and prevent further spread

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Speakers / sources featured

• Sources explicitly mentioned in the subtitles (not as speakers):
  • Pseudomonas malayi (organism)
  • Disinfectants: hypochlorite, iodine, mercuric chloride
  • Disease/test terms and assays: Mallein test, complement fixation test, indirect hemagglutination, conglutinant complement absorption, dot ELISA, Strauss reaction
  • Differential organisms: Histoplasma phaeosporinosis, Corynebacterium pseudoculosis, Sporotrichum senkai
  • Legal references: Glanders and Far(s) Act (as stated), Glanders and Horses Act of India
• No human speaker names are provided in the provided subtitles.