Great Plague of London

The Great Plague of London was a devastating outbreak of bubonic plague that occurred in 1665-1666, killing an estimated 100,000 people—about a quarter of London’s population. Caused by the bacteria Yersinia pestis, it spread through fleas carried by rats and also through person-to-person contact. The disease caused painful swelling of lymph nodes (buboes), fever, and chills. Urban overcrowding, poor sanitation, and close living conditions facilitated its rapid spread. The plague led to widespread fear, quarantine measures, and eventually contributed to public health reforms. It marked one of the last major outbreaks of bubonic plague in England.