People usually get it from a flea bite. It may cause swelling in the neck, under the arm, or in the groin area. Septicemic plague occurs when the plague bacteria get into the blood. This could happen through an open cut on the skin. People get very ill with this form of plague.
Pneumonic plague is the least common, but most dangerous, form of plague.
In this form, the bacteria get into the lungs and can be easily passed from one person to another through coughing and sneezing. Cats can get this form and pass it to people, also. Symptoms About 2 to 6 days after being bitten by an infected flea, a person with plague will have fever, restlessness, confusion, extreme tiredness, and other flu-like symptoms. A few days later, one or more buboes may develop. If the person is not treated by a doctor, they may become very ill and even die.