capsular FI antigen

Virulence V/W antigen

Ratotoxins or exotoxins (toxic proteins): Very toxic to mice and rats

Endotoxins (Lipopolysaccharide):

Main reservoir hosts: Chlorophytes and spp.

Secondary reservoir hosts: Rattus norvegicus and Rattus yellow-breasted, but they are the main sources of human plague infection.

Rat flea bites: rodents – rat fleas – humans

spread through skin

Respiratory droplet transmission

Bubonic plague: 2-5 days

Primary pneumonic plague: hours to 3 days

Bubonic plague: hemorrhagic inflammation and coagulative necrosis of lymph nodes

Pneumonic plague: lung lesions are mainly congestion, edema, and hemorrhage

Septicemic plague: Congestion, edema, hemorrhage and necrosis may occur in various tissues and organs throughout the body.

Yersinia pestis - bubonic plague - septicemic plague - secondary pneumonic plague - primary pneumonic plague

（1） Bubonic plague: The most common, with swollen lymph nodes (unilateral) as the main feature. Prevalent parts: inguinal lymph nodes, armpits, neck and submandibular lymph nodes. Summary: large, hard, painful, and fixed.

（2） Septicemic plague: The most dangerous type, with extremely high case fatality rate. Due to extensive bleeding, ecchymosis, cyanosis, and necrosis of the skin, the body turned black and purple after death, commonly known as "Black Death".

（3） pneumonic plague

（4） Mild plague: mouse plague, mild fever, local lymph node enlargement, mild tenderness, and occasional suppuration.

（5） Other types of plague:

Isolate the bubonic plague until the lymphadenopathy has completely dissipated and then observe for 7 days

Pneumonic plague is isolated until sputum culture is negative 6 times

Contacts will be under medical observation for 9 days, and those who have received vaccinations should be quarantined for 12 days