Yersinia pestis is a type of bacteria that can be transmitted to humans through the bite of an infected flea or rodent. It’s responsible for the bubonic plague, also known as the Black Death, and can cause symptoms such as a skin lesion at the bite site, fever, headache, and swollen lymph nodes.
This is a serious and often fatal disease if not treated promptly. It was the main cause of death for over 30% of Europe’s population in the 14th century. Today, it is extremely rare in the United States, with only a few cases reported each year, mostly in rural areas of the Southwest.
Treatment for Yersinia pestis infection should begin as soon as symptoms appear. A general practitioner or infectious disease specialist typically prescribes antibiotics.
Main symptoms
The main symptoms of Yersinia pestis infection include:
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Skin lesion at the flea bite site
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Sudden fever over 100.4°F (38°C)
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Persistent chills and shivering
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Severe headache
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General weakness
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Painful, swollen lymph nodes, especially in the armpits or neck
When the bacteria enters the bloodstream, additional symptoms may occur, such as a rapid heart rate, low blood pressure, shock, severe abdominal pain, and purple skin patches.
Symptoms usually begin 2 to 8 days after exposure to the bacteria.
Confirming a diagnosis
A diagnosis of Yersinia pestis infection is made by an infectious disease specialist based on symptoms and a history of being in areas where the disease is known to occur.
To confirm the presence of Yersinia pestis, the doctor may order tests such as sputum, blood, or fluid analysis, and may also perform a biopsy of the affected lymph node.
How transmission occurs
Yersinia pestis can spread to humans in several ways:
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Bites from infected fleas
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Contact with the blood, secretions, or tissues of infected animals
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Scratches or bites from contaminated cats
Less commonly, transmission can happen through droplets in the air from vomit, sneezing, or coughing. In these cases, the bacteria can spread from person to person, so treatment is often carried out in isolation to prevent further transmission.
Bacteria life cycle
Fleas feed on blood, mainly from rodents. If a rodent is infected with Yersinia pestis, the flea becomes infected while feeding. When the rodent dies, the infected flea looks for new hosts to feed on.
This allows the bacteria to spread to other rodents or animals, such as cats or humans, through flea bites.
Each flea can stay infected for months, increasing the chance of spreading the disease to more people and animals. Symptoms typically appear between 2 and 6 days after infection.
Treatment options
Treatment for Yersinia pestis infection should begin as soon as possible under the guidance of an infectious disease specialist, as the bacteria can lead to death in less than 24 hours if left untreated.
Treatment is usually provided in a hospital isolation unit using intravenous antibiotics. The most commonly used antibiotics include:
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Streptomycin
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Tetracycline
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Gentamicin
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Doxycycline
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Chloramphenicol
After symptoms and fever are stabilized, the person can usually return home but must continue taking antibiotics for up to 10 days, even if symptoms have resolved.
How to prevent infection
Prevention is based on controlling rodents and other pests. This includes avoiding garbage accumulation, using flea treatments on pets, and applying insect repellent to avoid flea bites.
It’s also important to wear protective equipment when handling the blood, secretions, or tissues of animals that could be infected.