Glanders is a term describing a highly contagious and life-threatening infection caused by Burkholderia mallei. Because of its potential use as a biological weapon, vast efforts have been made to limit the possibility of human infection, but rare cases have been described in the past several decades. Many tissues can be infected by glanders, including the mucosal surfaces, the lungs, and the skin, while systemic infections and sepsis might also develop. Clinical findings and microbiological studies are necessary for the diagnosis.
Glanders has been long known as a highly contagious and frequently fatal infection of solipeds - horses, donkeys, and mules [1] [2]. Since its initial description, it has been discovered that the causative agent is Burkholderia mallei, a nonmotile gram-negative bacterial microorganism [1]. The majority of infections occurred after direct contact with infected animals, either through abrasions and breaks in the skin, inoculation onto mucosal surfaces (conjunctiva or the oral cavity), or by inhalation, and its highly contagious properties resulted in its classification as a biological weapon (category B) by the Center for Disease Control and Prevention (CDC) [1] [3]. Glanders is now very rarely diagnosed in the Western world because of large efforts to eradicate this bacterial pathogen through euthanizing infected animal hosts [1] [4], and only a few cases were reported in the past century, including a laboratory-acquired case in the United States [5]. However, cases have been reported from other continents, and a number of clinical manifestations are documented [1] [5] [6]. After a highly variable incubation period (several days to a few months), the first clinical symptoms start to appear [1]. Cough, chest pain, tachypnea, and dyspnea, often accompanied by high fever, chills, night sweats, headaches, vomiting, nausea, tachycardia, and fatigue in the case of pulmonary infections, are considered as the most severe form [1]. A papular erosion arising at the site of B. mallei entry with local inflammation and swelling is the main feature of cutaneous glanders, whereas photophobia, excessive lacrimation, nasal discharge, facial swelling, lymphadenopathy and progression to a pulmonary infection are hallmarks of a conjunctival or ocular infection [1]. Finally, disseminated infections and septicemia may develop [1].
The diagnosis of glanders might be quite difficult due to the nonspecific clinical presentation and rarity of the condition in clinical practice. For this reason, the physician should obtain a meticulous patient history during which recent contact with animal hosts (horses, donkeys, and mules) can provide crucial information. The physical examination, although essential for the assessment of the patient's general condition and observation of symptoms that may point to the tissue affected by the infection, will rarely reveal findings that are specific for glanders. Radiographic studies that have been performed in patients who suffered from this infection - ultrasonography and computed tomography (CT), discovered multiple abscesses in different organs (spleen, liver, lungs), but in order to make a definite diagnosis, microbiological identification is necessary [1] [5]. Specific tests for B. mallei are yet to be designed, which is why serological studies (complement fixation tests and indirect hemagglutination assays) are described as somewhat useful in recognizing glanders [1] [7]. Some studies, however, advocate the use of polymerase chain reaction (PCR) as a superior method for detection of B. mallei, although only animal subjects have been evaluated through this method so far [1] [2] [8].