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Plague
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Infections

Plague

Plague is a rare bacterial infection caused by Yersinia pestis, historically devastating but now manageable through modern antibiotics.

Overview

Plague is an infection caused by the bacterium Yersinia pestis. The bacteria are found mainly in rats and in the fleas that feed on them. People and other animals can contract the disease from rat or flea bites. While it once destroyed entire civilizations, it is now uncommon due to better living conditions and the availability of antibiotics.

Forms of Plague

  • Bubonic plague: Causes the tonsils, adenoids, spleen, and thymus to become inflamed. Symptoms include fever, aches, chills, and tender lymph glands.
  • Septicemic plague: Occurs when bacteria multiply in the blood, causing fever, chills, shock, and bleeding under the skin or in other organs.
  • Pneumonic plague: The most serious form, where bacteria enter the lungs to cause pneumonia. This form can be spread from person to person and could be a bioterror agent.

Diagnosis and Treatment

Lab tests are used to diagnose plague. Treatment involves a strong antibiotic. There is currently no vaccine.

Frequently Asked Questions

The most distinct early sign of bubonic plague is the sudden appearance of painful, swollen lymph nodes (buboes), typically in the groin, armpit, or neck, which often precede or accompany high fever, chills, and severe headache. Unlike the flu, where symptoms are generally systemic and diffuse, plague patients often report extreme tenderness in these specific glandular areas. If you have been in an area with known rodent activity or flea exposure and develop these specific symptoms, seek immediate medical attention, as early antibiotic treatment is critical for survival.
The incubation period for bubonic plague is typically 2 to 6 days, though it can range from 1 to 8 days. During this window, you may not feel ill, but if you recall a flea or rodent bite in an endemic area, you should monitor for fever and swollen glands. If symptoms develop, do not wait for them to worsen; go to an emergency department immediately and inform the triage staff of your potential exposure. Early administration of antibiotics like streptomycin or doxycycline significantly improves outcomes, while delayed treatment can allow the infection to progress to septicemic or pneumonic forms.
There is currently no widely available, FDA-approved vaccine for plague in the United States, though research is ongoing. Treatment relies on strong antibiotics, with streptomycin and gentamicin being the preferred first-line agents for severe cases, while doxycycline, ciprofloxacin, or chloramphenicol are used for less severe cases or prophylaxis. When administered early, antibiotics are highly effective, and the mortality rate drops significantly. However, if treatment is delayed until the infection has progressed to septicemic or pneumonic stages, the mortality rate can rise sharply, underscoring the importance of rapid diagnosis and intervention.
Yes, pneumonic plague is the only form that spreads directly from person to person through respiratory droplets when an infected individual coughs, sneezes, or talks. This makes it highly contagious and potentially a bioterrorism agent. In contrast, bubonic and septicemic plague are primarily transmitted via flea bites or direct contact with infected animal tissues and do not spread easily through the air. Because pneumonic plague can be fatal within 24 to 72 hours if untreated, anyone with a confirmed case is isolated, and close contacts are often placed on prophylactic antibiotics to prevent secondary transmission.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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