Explore the recorded discovery and history of Yersinia pestis, with source links and stated limits.
PHAC describes Y. pestis as a Gram-negative coccobacillus 1 to 3 micrometres in length, ovoid in shape, with characteristic bipolar staining giving a safety-pin appearance; it is non-motile, does not form spores, and grows optimally at 29 to 30 degrees Celsius while surviving from 4 to 40 degrees Celsius. PHAC records 4,547 reported plague cases worldwide from 21 countries between 2010 and 2019, with 94% of reported cases in either the Democratic Republic of the Congo or Madagascar; WHO names the Democratic Republic of the Congo, Madagascar and Peru as the three most endemic countries. Transmission is most commonly through the bite of infected rodent fleas, with pneumonic plague additionally spreading by respiratory droplets.
LPSN records the basonym “Bacterium pestis” Lehmann and Neumann 1896. The epithet comes from the Latin pestis, an infectious or contagious disease, plague — the name records the disease rather than the organism’s features.
LPSN records Yersinia pestis (Lehmann and Neumann 1896) van Loghem 1944, effectively published in Antonie van Leeuwenhoek in a paper on the classification of the plague bacillus, and retained on the 1980 Approved Lists of Bacterial Names. The genus honours Alexandre Yersin. Type strain ATCC 19428 / NCTC 5923.
PHAC records a 2017 outbreak in Madagascar with 597 cases, of which 418 were pneumonic, and 55 deaths. It is included here because it shows the disease is current rather than historical, and because the high pneumonic proportion is unusual; it is not the origin of plague.
These references do not identify a first person ever infected. Plague epidemics are described in historical records centuries before the organism was isolated in the 1890s, so naming milestones cannot date a first case, and the sources bundled here do not establish where the species arose.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.