Plague pneumonia disease caused by Yersinia pestis

Plague is a zoonotic infection caused by Yersina pesits, a pleomorphic, gram-negative non-spore-forming coccobacillus that is more accurately classified as a subspecies of Y pseudotuberculosis. Animal reservoirs include rodents, rabbits, and occasionally larger animals. Cats become ill and have spread pneumonic disease to man. Dogs may be a significant sentinel animal as well as a reservoir, although do not usually become ill. Flea bites commonly spread disease to man. Person to person spread has not been a recent feature until the purported outbreak of plague and plague pneumonia in India in 1994. Other factors that increase risk of infection in endemic areas are occupation-veterinarians and assistants, pet ownership, direct animal-reservoir contact especially during the hunting season, living in households with an index case, and, mild winters, cool moist springs, and early summers. Clinical presentations include subclinical plague (positive serology without disease); plague pharyngitis; pestis minor (abortive bubonic plague); bubonic plague; septicemic plague; pneumonic plague; and plague meningitis. Most prominent of plague's differential diagnosis are Reye's syndrome, other causes of lymphadenitis, bacterial pneumonias, tularemia, and acute surgical abdomen. Treatment has reduced mortality from 40-90% to 5-18%. The drug of choice (except for plague meningitis) is streptomycin, with tetracyclines being alternatives. Parenteral cholamphenicol is the treatment of choice for plague meningitis. A tetracycline should be administered as chemoprophylaxis to all contacts over the age of 8 years. Plague vaccine is available, but is only partially protective.