Pathogenicity: Causes plague, "The Black Death", so named because of the dark blue areas of skin caused by hemorrhages. In the 14th century this disease destroyed an estimated 25% of the total population of Europe. It can proliferate and survive within phagocytes causing the lymph nodes of groin and armpit to become enlarged producing "buboes"; fever; death in untreated cases is usually within one week of onset of symptoms. There is a mortality rate of 50 to 75%. If bacteria enters lungs, causing "pneumonic plague", the mortality rate reaches nearly 100%.
Transmission: May be transmitted by a vector - fleas; direct contact with animals through skinning or scratches; respiratory droplets from infected people. This organism can initiate disease from more than one portal of entry - their preferred method is through the skin or parenteral router (deposition directly into the tissues beneath the skin and mucous membranes).
Yersinia pestis
