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How can bubonic plague develop into septicemic plague?

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two plague victims with sores lying in bed, while a robed figure gestures above them. — plague Image depicting victims of the sixth biblical plague.

Bubonic plague can progress into septicemic plague when the Yersinia pestis bacteria, which typically colonize and multiply within the lymph nodes, escape into the bloodstream.12

While the infection usually begins when bacteria migrate through the lymphatic system to form painful swellings known as buboes, the bacilli can occasionally enter the circulatory system directly from these nodes or from the initial site of infection. Once the bacteria invade the bloodstream, they cause a systemic infection known as septicemia, or blood poisoning, which characterizes the septicemic form of the disease.12

If left untreated, this progression is highly dangerous, as septicemic plague can lead to death even before the characteristic buboes of the bubonic form have time to appear. Prompt treatment with antibiotics is essential to prevent this severe complication and protect the patient's life.312