Explore the recorded discovery and history of Listeria monocytogenes, with source links and stated limits.
PHAC describes L. monocytogenes as a Gram-positive, non-spore forming, rod-shaped coccobacillus measuring 0.5 to 2 micrometres long and 0.5 micrometres in diameter, able to reproduce at temperatures between 1 and 45 degrees Celsius and across pH values from 4.3 to 9.6 — which is why refrigeration does not stop it. CDC estimates that 1,250 people are infected with Listeria and 172 people die from the infection each year in the United States, and describes it as the fourth leading cause of death from foodborne illness there. CDC also states that people outside the higher-risk groups can be infected but rarely become seriously ill, so the same organism produces very different outcomes depending on who eats it.
LPSN records the basonym “Bacterium monocytogenes” Murray et al. 1926. The epithet means monocyte-producing, after the blood-cell change seen in the laboratory animals in which the organism was first studied — a laboratory observation, not a description of human illness.
LPSN records Listeria monocytogenes (Murray et al. 1926) Pirie 1940, effectively published in Science, and retained on the 1980 Approved Lists of Bacterial Names. Type strain ATCC 15313 / DSM 20600 / NCTC 10357.
These references do not identify a first person ever infected. The 1926 description came from laboratory animal work, and the 1940 milestone is a naming decision, so neither dates a first human case or a geographic origin.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.