Plague

Abstract

Yersinia pestis, the causative organism of plague, has become of interest recently because of its potential as a weapon in bioterrorism. Y. pestis is a nonmotile, Gram-negative bacillus. Humans are accidental hosts in the natural cycle of plague. Rats, prairie dogs, and squirrels serve as the most common reservoirs of Y. pestis. Y. pestis invades a human host’s lymphoid tissue once introduced through a fleabite. This naturally occurring form of the plague is referred to as bubonic plague. Symptoms of bubonic plague include sudden onset of fever; chills; weakness; and a painful, swollen, erythematous lymph node known as a bubo. Another form of the disease, known as primary pneumonic plague, is transmitted in aerosolized form and infects the lungs, causing rapid death if not treated quickly. This aerosolized form of Y. pestis poses the biggest threat in biological warfare because person-to-person transmission occurs readily. Symptoms of primary pneumonic plague include dyspnea, cough, hemoptysis, and bronchopneumonia. Appropriate antibiotics for treatment of plague include streptomycin, gentamicin, tetracycline, doxycycline, ciprofloxacin, and chloramphenicol. At present, no vaccine is available that protects against pneumonic plague.