Plague is a severe, and potentially deadly, infection. It is caused by the organism Yersinia pestis. Wild rodents, like rats, spread the disease to humans.
- When a person is bitten by an infected flea or is infected by handling an infected animal, the plague bacteria move through the bloodstream to the lymph nodes. The lymph nodes swell, causing the painful lumps ("buboes") that are characteristic of bubonic plague. Other symptoms are fever, headache, chills, and extreme tiredness. Some people have gastrointestinal symptoms.
- If pharyngeal plague goes untreated, the bacteria can multiply in the bloodstream and produce plague septicemia (septicemia plague), severe blood infection. Signs and symptoms are fever, chills, tiredness, abdominal pain, shock, and bleeding into the skin another organs. Untreated septicemia plague is usually fatal.
- Pharyngeal plague, develops when the bacteria infect the lungs. People with plague pneumonia have high fever, chills, difficulty breathing, a cough, and bloody sputum. Plague pneumonia is considered a public health emergency because a cough can quickly spread the disease to others. Untreated pneumonic plague is usually fatal.