Profiles for Health Care Workers (Fact Sheets) - "B" Agents
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Glanders is a zoonotic disease caused by the gram-negative bacillus Burkholderia mallei. Though primarily a disease of horses, mules, and donkeys, human illness can sometimes occur. Glanders is endemic in parts of Africa, Asia, Europe, and Central and South America.
Routes of Exposure:
Humans are primarily exposed to glanders through direct contact with infected animals. Infective Dose & Infectivity: The infective dose is assumed to be low and all people are considered susceptible.
The incubation period ranges from 10 to 14 days.
Infection with glanders can range from asymptomatic acquisition to life-threatening pneumonia and bacteremia. Pulmonary infection can occur from inhalation or hematogenous spread. Chest radiographs can show lobar pneumonia, pulmonary abscesses, pleural effusions, and/or small military lesions. Bacteremia is accompanied by signs of sepsis and can include abscesses throughout the body and multiple cutaneous pustules. Mucous membrane infection manifests as nasal ulcers and nodules that secrete a bloody discharge. After contamination of broken skin, local ulcerative lesions develop with enlarged regional lymph nodes. Some people develop chronic infection with necrotizing granulomas in the liver and spleen and muscles of the arms and legs.
When untreated, septicemia is usually fatal within 7-10 days.
B. mallei is generally transmitted from animals to humans by invasion of nasal, oral, and conjunctival mucous membranes; by inhalation into the lungs; or through lacerated or abraded skin. Additionally, direct contact with an infected person’s body fluids can lead to person-to-person transmission.
Primary contaminations & Methods of Dissemination:
As a bioterrorism weapon, glanders would most likely be delivered via aerosolization.
Secondary Contamination & Persistence of organism:
Secondary cases may occur through improper handling of infected secretions. However, humans have seldom acquired infection from infected animals despite frequent and close contact.
Decontamination & Isolation:
- Patients – Standard precautions should be practiced. Contact precautions should be used with skin lesions and secretions. Patients with direct exposure to aerosols should be washed with soap and water.
- Equipment, clothing & other objects – 0.5% hypochlorite solution (one part household bleach and 9 parts water = 0.5% solution) is effective for environmental decontamination.
Gram stain of lesion exudates reveals small gram-negative bacteria. These stain irregularly with methylene blue. B. mallei grows slowly on ordinary nutrient agar. Agglutination tests are not positive for 7-10 days, and a high background titer in normal sera (1:320 to 1:640) makes interpretation difficult. Complement fixation tests are more specific and are considered positive if the titer is equal to, or exceeds 1:20. Cultures of autopsy nodules in septicemic cases will usually establish the presence of B. mallei.
There is little experience in treating glanders in humans; therefore few antibiotics have been evaluated in vivo. Treatment varies with the type and severity of the clinical disease. Severe disease requires initial parenteral therapy. Prolonged oral antibiotic therapy for many months is required to prevent relapse. Parenteral regimens have included combinations such as cetazidime and trimethoprim-sulfamethoxazole, or imipenem and doxycycline. Various isolates have markedly different antibiotic sensitivities, so each isolate should be tested for its own individual resistance pattern.
There is no vaccine available for human use. Post-exposure chemoprophylaxis has not been established, although it has been suggested that trimethoprim-sulfamethoxazole may be tried.
The differential diagnosis depends on the clinical manifestations. In addition to common causes of pneumonia, potential agents of bioterroism and zoonotic diseases would include melioidosis, plague, and tularemia. The papular or pustular skin lesions of glanders can resemble the rash of smallpox.
- Marty AM. Melioidosis and Glanders In: Physician’s Guide to Terrorist Attack. Roy MJ, ed. Physician’s Guide to Terrorist Attack. Totowa, NJ: Humana Press, Inc.; 2004:143-159
- Kortepeter M, Christopher G, Cieslak T, et al. Medical Management of Biological Casualties Handbook, U.S. Army Medical Research Institute of Infectious Diseases, U.S. Department of Defense; 2001: 37-42
Find the PDF version of this Fact Sheet in the Zebra Manual.