Glanders: causes, symptoms, diagnosis, and treatment

Glanders, also known as farcy, is an infectious disease mainly in solipeds such as horses and donkeys. Occasionally, the disease can be transmitted to humans, causing fever, swollen lymph nodes, skin mucosal lesions, and upper respiratory tract infections. In severe cases, the disease can be fatal.


Causes

Burkholderia mallei is a Gram-negative aerobic bacterium. The bacterium is 5 - 7μm long and resembles corynebacterium diphtheriae. Horses are an important source of infection, and humans are infected by direct contacts with pathogens in the oral and nasal secretions of the infected animals. Burkholderia mallei enters the body through tiny wounds in the skin or mucous membranes. The incidence is associated with occupation, the disease is more common in persons closely contacting with the infected animals, and laboratory workers can be infected through the respiratory tract.


Signs and Symptoms

The incubation period is several days to three weeks. The initial symptoms are fever, headache, and fatigue. Skin lesions are inflammatory papules or vesicles at the site of inoculation, rapidly developing into nodules, pustules, and ulcers, forming irregular depressions with undermined edges, with bases covered by purulent and hemorrhagic exudates. After several days or weeks, other nodules occur along the lymphatic vessels in the adjacent skin and subcutaneous tissue, which are called farcy buds. Subsequently, these nodules rupture, forming abscesses and sinus tracts, with local lymphadenopathy, with pain.

The respiratory mucosa is particularly susceptible to this disease. After accidental inhalation of the bacteria, catarrh occurs initially and is accompanied by nasal hemorrhage and mucoid nasal discharge that is a specific manifestation of the disease. Large areas of necrosis can occur in the hard palate and nasal septum. Under severe conditions, sepsis can occur and involve multiple organs, resulting in disseminated meningoencephalitis, pneumonia, and polyarthritis.

In acute cases, severe skin symptoms and deteriorated general condition may cause death quickly. In chronic cases, mild systemic symptoms are present, cutaneous nodules, abscesses, and ulceration relapse repeatedly, with local lymphadenopathy, and death results from failure after several months to years. Some patients can spontaneously heal.


Diagnosis

Clinically, the occupation in suspicious persons and a history of exposure to the infected animals should be noticed. Gram-negative Burkholderia mallei found in the nasal secretions or skin ulcers and positive results in the serum agglutination test can assist in the definitive diagnosis.


Treatment

The skin lesions at the inoculation site should be excised as soon as possible, and a combination treatment of antibiotics such as sulfonamides, streptomycin, tetracycline, and chloramphenicol for more than 4 weeks should be performed. In vitro studies have shown that the bacteria are highly sensitive to cephalosporins, kitasamycin, doxycycline, imipenem, and ciprofloxacin, which can be used in combination.