Formerly classified as Pseudomonas mallei, the organisms are Gram negative rods with rounded ends, 1.5–3.0 μm long and 0.3–0.6 μm wide, which often stain irregularly. They have no flagellae and are therefore non-motile. The organism is not highly resistant to environmental conditions.
The disease in humans is rare or absent in most parts of the world. Enzootic foci exist in Asia, some eastern Mediterranean countries and parts of the Middle East and central and South America.
Primarily a disease of equines, including horses, donkeys and mules, for which it is highly contagious.
Mode of transmission
The disease is acquired by humans by direct contact with infected animals or contaminated animal tissue, the agent entering the body through skin lesions or through conjunctival, oral or nasal mucous membranes. The disease is not considered to be very contagious from person to person. It is likely to be infectious by aerosol exposure.
Although most cases appear 1–14 days after exposure, the disease can remain latent for many years.
Glanders infection can present in several forms, depending on the route of entry and the site of infection. Initial symptoms may include fever, malaise, myalgia and headache. Localized infection may become apparent a few days after exposure, with pus-forming ulcerations on the skin that may spread over most of the body, or as purulent ulcerations of the mucosa of the nose, trachea, pharynx and lungs.
Pulmonary infection is associated with pneumonia, pulmonary abscesses and pleural effusion. Localized infection in the lobes of the lungs may be apparent in chest X-rays. Untreated bloodstream infections are usually fatal within a few days. Chronic infections are associated with multiple abscesses in the muscles of the arms and legs, or in the spleen or liver. Sub-clinical infections are sometimes detected at autopsy.
Identification may be made by isolation of the microorganism from skin lesions, pus, sputum or blood, followed by direct fluorescent antibody staining or by PCR. Serological tests include complement fixation, agglutination tests and ELISA. Bio-safety Level 2 practices, equipment and facilities are recommended for manipulations involving clinical specimens or experimentally infected laboratory rodents.
Bio-safety Level 3 practices, equipment and facilities are recommended for manipulations involving the concentration of cultures or activities with a high potential for aerosol production.
Medical management and public health measures
Standard precautions should be observed against infection from splashes or other direct contact with draining lesions, blood and contaminated discharges or other contaminated materials. Exudates and dressings should be disinfected by autoclaving, incineration or treatment with standard disinfectants.
Prophylaxis and therapy
No vaccine is available. Owing to the rareness of the disease, the medical literature regarding its therapy is sparse. Sulfadiazine and ceftazidime are recommended for therapeutic use. The organism is also sensitive to tetracyclines, ciprofloxacin, streptomycin, novobiocin, gentamicin, sulfonamides, or a combination of imipenem and doxycycline. There may be relapses even after prolonged antimicrobial therapy.