Infectious Disease Online
Pathology of Glanders
Glanders was first described as a disease of horses in 450 BC by Hippocrates.
Its bacterial aetiology was established in 1882 when the bacillus (now known as Burkholderia mallei) was isolated from a horse dying of glanders.
The cause is Burkholderia mallei, a small, gram-negative, nonmotile bacillus.
Human glanders has both acute and chronic forms, and affects mainly the respiratory system, the skin and subcutaneous soft tissues.
Glanders is a recognized occupational risk for veterinarians, equine butchers, stable hands and laboratory workers.
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The causative agent of glanders, Burkholderia mallei, is highly contagious and leads to chronic disease in horses whereas in donkeys and mules the disease is acute and often fatal.
In humans Burkholderia mallei infection results in a severe clinical course, and is fatal without appropriate therapy.
Its pathogenicity makes Burkholderia mallei a potential biological agent that may be used in bioterroristic attacks.
Although uncommon, glanders remain endemic in South America, Asia, and Africa.
In addition there have been rare infections of laboratory workers in the United States and Canada.
The natural reservoir is equines and transmission to human is by contact through broken skin or by inhalation of contaminated aerosols.
Glanders may also be transmitted from person to person.
The acute disease is characterized by papule at the site of inoculation, followed by bacteremia with severe prostration, fever, vomiting, and generalized pain.
The bacilli drain from the primary papule through lymphatics to regional lymph nodes and then to the blood stream.
Abscesses may form along the draining lymphatics, in the regional nodes and in many organs throughout the body, including the lung, liver, spleen, muscle, joints, and especially the subcutaneous tissues.
The abscesses are composed of a central zone of neutrophils surrounded by a granulomatous perimeter.
Patients with the chronic form of glanders show a low-grade fever, draining abscesses of skin, lymphadenopathy, and hepatospenomegaly.
The lesions begin as abscesses and evolve to granulomas, mimicking tuberculosis.
In its acute form, glanders is almost always fatal, and in the chronic form mortality is more than 50%.
Occurrence of the disease leads to international trading restrictions and infected animals should be immediately culled and safely disposed off.
Some success in treatment has been achieved with sulfonamides.
The lesions are not pathognomonic, and the diagnosis depends on the isolation of Burkholderia mallei or the detection of compliment-fixing antibodies.
Although Burkholderia mallei may be cultured from blood, sputum or pus, its high potential for causing laboratory-acquired infection requires strict containment.
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