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Bubonic plague

The common form of plague, the one behind the Black Death, and today a disease that oral antibiotics cure in most patients treated in time.

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What bubonic plague is

Bubonic plague is the most common form of plague, about 80 to 95 percent of cases worldwide. Yersinia pestis enters through the skin, usually from a flea bite, travels through the lymphatic system to the nearest lymph node and multiplies there. The node swells into a tense, painful lump called a bubo, which gives the disease its name.

How people catch it

  • Flea bites. Fleas that fed on infected rodents, above all the oriental rat flea Xenopsylla cheopis.
  • Handling infected animals. Skinning or butchering rodents, marmots, rabbits or other wildlife without gloves.
  • Eating infected meat. In Mongolia, 7 percent of human cases since 1998 followed eating raw marmot organs, and 59 percent close contact with infected marmots.
  • Pets. Cats are highly susceptible and can carry infected fleas into the home.

Bubonic plague rarely passes between people. Without lung involvement it does not spread through the air.

Symptoms

After an incubation of 1 to 7 days (WHO) or 2 to 8 days (CDC), symptoms start suddenly:

  • fever, chills, headache, body aches and weakness
  • nausea and vomiting
  • one or more swollen, very painful lymph nodes, usually in the groin, armpit or neck

Untreated, the infection can move into the blood (septicemic plague) or the lungs (pneumonic plague), and buboes can turn into open sores.

How dangerous it is

WHO puts the fatality of untreated bubonic plague at 30 to 60 percent; CDC cites 66 percent untreated, falling to 13 percent with antibiotics. In US data, only 9 percent of patients who received at least one dose of an effective antibiotic died, against 52 percent of those who did not.

Treatment

First-line antibiotics for bubonic plague include ciprofloxacin, levofloxacin, moxifloxacin, doxycycline, gentamicin and streptomycin, for 10 to 14 days. A 2025 randomised trial in Madagascar found that 10 days of oral ciprofloxacin alone worked as well as injected drugs followed by ciprofloxacin, which makes treatment possible far from hospitals. See treatment.

Where it occurs

Most human cases reported to WHO between 2019 and 2025 came from DR Congo and Madagascar. Madagascar usually notifies 200 to 400 cases a year, mostly bubonic, in a September to April season. The US averages about seven cases a year in the rural West; Mongolia, China, Peru and Kyrgyzstan report sporadic cases. See the plague map and country profiles.

Prevention

  • Never handle a wild animal found dead; report die-offs of rodents to local authorities.
  • Wear gloves when skinning or butchering animals in endemic areas; do not eat sick animals.
  • Use insect repellent (DEET on skin, permethrin on clothes) outdoors in endemic areas.
  • Treat pets for fleas and keep free-roaming pets off your bed in endemic areas.
  • Seek care at once for fever with a painful swollen lymph node after a possible exposure.

Reference information, not medical advice. With symptoms after a possible exposure, call your local emergency number.

Sources

  1. 01WHO: Plague fact sheet
  2. 02CDC: Signs and symptoms of plague
  3. 03CDC: How plague spreads
  4. 04CDC MMWR: Antimicrobial treatment and prophylaxis of plague (2021)
  5. 05WHO guidelines for plague management (2021)
  6. 06ECDC: Plague factsheet
  7. 07CDC: Plague maps and statistics
  8. 08Kugeler et al., Emerg Infect Dis 2015
  9. 09Randremanana et al., N Engl J Med 2025 (oral ciprofloxacin trial)
  10. 10Kehrmann et al., Emerg Microbes Infect 2020
  11. 11CDC: Preventing plague
Pneumonic plagueThe form that spreads between peopleSymptomsAll three forms comparedPlague mapNatural foci worldwide