Pneumonic plague is a type of bubonic plague, which is spread mainly through skin infections, digestive tract infections, respiratory infections and rat flea bites. 1. Skin infection: Pneumonic plague can be spread by eating the skin of diseased rodents, or by direct contact with pus, blood or sputum, and then through skin wounds. 2. Digestive tract infection: Pneumonic plague can also be contracted by eating undercooked meat that has been infected with bacteria. 3. Respiratory tract infection: Pneumonic plague can also be contracted through the respiratory tract, such as breathing droplets, breathing, talking and coughing, so that the droplets spread to the human body, thus causing pneumonic plague. 4. Bite of rat fleas: It can be spread through rat fleas. Rat flea bites are a very important mode of transmission. The main transmission route of plague is animals from rodents to fleas to humans. Personal protection is recommended. Strong isolation of patients should be practiced as such patients are highly contagious.