Yersinia pestis: Yersinia pestis is a Gram-negative bacterium that belongs to the genus Yersinia pestis.

Route of transmission: Mainly transmitted to humans through flea bites or direct contact with infected animal body fluids.

Bubonic plague: mainly invades lymphoid tissue and is characterized by enlarged lymph nodes.

Pneumonic plague: mainly affects the respiratory tract and is the most serious type.

Septicemic plague: Infects multiple organs throughout the body, the disease is the most serious.

Fever: Plague is often accompanied by high fever, which can exceed 39°C.

Headache: Patients often experience headache symptoms that last for a long time.

Fatigue: The patient feels very tired and the fatigue persists, affecting normal life.

Muscle aches: The patient experiences muscle aches throughout the body, similar to cold symptoms.

Symptoms of the bubonic plague stage: If bubonic plague is not treated, lymph node enlargement gradually worsens, and abscesses, ulcers, etc. may occur.

Symptoms of the alveolar stage: If pneumonic plague is not treated in time, patients can enter the alveolar stage within a few hours, with obvious symptoms such as difficulty breathing, coughing and hemoptysis.

Symptoms of the physical illness stage: If septicemic plague is not treated in time, the condition will deteriorate rapidly, leading to multiple organ failure throughout the body, manifesting as high fever, coma, shock and other serious symptoms.