Yersinia pestis · Still active today

Bubonic Plague

The disease behind the Black Death is not history — it still infects 1,000–2,000 people a year. What it is, how it spreads, the symptoms, and why modern antibiotics make it survivable.

Short answer

Bubonic plague is a bacterial infection caused by Yersinia pestis, spread mainly by flea bites from infected rodents. It causes fever and painful swollen lymph nodes (buboes). Untreated it kills 30–60%; with early antibiotics most people recover. It still causes about 1,000–2,000 cases a year worldwide, mainly in Madagascar, the DR Congo and Peru.

Key facts

2–8 days

Incubation

30–60%

Untreated fatality

~10%

Treated fatality

1–2K/yr

Cases worldwide

The three forms of plague

Bubonic — the classic form. Flea bite → swollen, painful lymph nodes (buboes). 30–60% fatal untreated.
Septicemic — the bacteria multiply in the bloodstream, blackening fingers and toes (origin of the name “Black” Death). Near-universally fatal untreated.
Pneumonic — infection of the lungs, the only form that spreads person-to-person by airborne droplets. Fatal within 2–3 days untreated.

How it spreads

The classic cycle runs rodent → flea → human. A flea feeds on an infected rodent, the bacteria block its gut, and when the starving flea bites a human it regurgitates Yersinia pestis into the wound. Bubonic plague on its own is not contagious between people — the fear comes from its ability to progress to pneumonic plague, which is.

Treatment today

Modern antibiotics make plague survivable when caught early: gentamicin, the fluoroquinolones (ciprofloxacin, levofloxacin) and doxycycline. Treatment started within 24 hours cuts mortality dramatically. The key risk is delay — plague is rare enough that doctors may not consider it quickly.

Frequently asked questions

What is bubonic plague?

A serious bacterial infection caused by Yersinia pestis, named for the painful swollen lymph nodes (buboes) it produces. Usually transmitted by infected flea bites. Untreated it kills 30–60%; with prompt antibiotics most recover.

What are the symptoms?

2–8 days after infection: sudden fever, chills, headache, weakness, then one or more swollen, extremely painful lymph nodes (buboes), often in the groin or armpit. Untreated it can spread to blood (septicemic) or lungs (pneumonic).

How is it transmitted?

Mostly by the bite of a flea that fed on an infected rodent. People can also catch it handling infected animal tissue. Bubonic plague does not spread person-to-person — but pneumonic plague can, via respiratory droplets.

Is bubonic plague still around today?

Yes — the WHO records roughly 1,000–2,000 human cases a year, mainly in Madagascar, the DR Congo and Peru. The US averages about 7 cases a year in the rural Southwest.

Can bubonic plague be cured?

Yes, with antibiotics (gentamicin, ciprofloxacin, doxycycline), especially within 24 hours of symptoms. Early treatment drops mortality from 30–60% to around 10%.

What is the difference between bubonic plague and the Black Death?

Same bacterium, Yersinia pestis. 'Bubonic plague' is the disease that still occurs today; the 'Black Death' was the 1346–1353 pandemic that killed 75–200 million people.

How can you prevent plague?

Reduce rodent and flea exposure: flea-control on pets, avoid dead/sick rodents, use repellent in endemic areas, rodent-proof homes. No vaccine is widely available for the public.

History

The Black Death — the 1346 pandemic

Pandemic

Spanish Flu 1918 — 50M dead

Disease

Cholera — cause & the 7 pandemics

Tool

PlagueAtlas home — interactive map

Informational only — not medical advice. For symptoms, contact a healthcare professional.