A20-A28: Certain zoonotic bacterial diseases

A20: Plague

The plague represents a group of infectious diseases caused by the bacterium Yersinia pestis, commonly found in small mammals and their fleas. It's transmitted to humans through the bite of an infected flea, contact with contaminated fluid or tissue, or inhaling respiratory droplets from a person or animal with plague pneumonia. The plague typically presents in three forms: bubonic, septicemic, and pneumonic. Bubonic plague, the most common type, is characterized by sudden onset of fever, headache, chills, and weakness, followed by painful swollen lymph nodes. Septicemic plague, where bacteria multiply in the bloodstream, can occur as the first symptom of the plague or may develop from untreated bubonic plague. Pneumonic plague affects the lungs and can spread from person to person. The disease can be fatal if not treated promptly, with death occurring within a day of onset in pneumonic cases.