Yersinia pestis Flashcards
Yersinia pestis
Black Plague
Structure
small, pleomorphis, facultatic anaerobe, gram-negative bacillus
Transmitted by
vector
-30 different fleas
-Xenopsylla cheopis(rat flea), Oropsylla montanus (squirrel flea) most common
Is it zoonotic
yes
How long does it last in the environment
<1hour
History
-Europe 1347-1351 from east china
-about 45 million people died
-spread by rats in chips
-lead to persecution of cats->made it worse
Transmission Cycle
-Naive animal/human bit by flea
-direct transmission
-inhalation
Reservoirs
No persistent reservoirs because it is deadly but prefers rodents
domestic cats and black-footed ferrets have high mortality
There are four classification
-rodent species that serve as enzootic reservoir
-rodent species that amplify infections beyond enzootic foci
-resistant non-reservoir hosts, birds, ungulates, and most carnivores
-susceptible non-rodent hosts that may promote some transmission but generally not involved in ecological maintenance
Pathogenesis
transferred through saliva-> phagocytosed by macrophages-> some bacteria killed others kill macrophage-> ruptured from cell-> now cannot be phagocytosed
Spread to draining lymph nodes->transported to liver, spleen, and lungs-> severe bacterial pneumonia-> causes hemorrhage and death
Incubation
1-7 days
Bubonic Clinical Signs
fever, lethargy, swollen, abscessed lymph nodes
-vomiting, diarrhea cellulitis
Pneumonic clinical signs
fever, chills, respiratory distress, coughing
Septicemic clinical signs
fever, lethargy, abdominal pain, anorexia, vomiting, diarrhea, tachycardia, pale mucous membranes
Pathologic lesions
hemorrhagic buboes
necrotic nodules in liver, spleen, and lungs
splenomegaly
suppurative pneumonia
