[2] Listeria is ubiquitous and is primarily transmitted via the oral route after ingestion of contaminated food products, after which the bacteria penetrates the intestinal tract to cause systemic infections.

The disease primarily affects older adults, persons with weakened immune systems, pregnant women, and newborns.

This infection occurs after direct exposure to L. monocytogenes by intact skin and is largely confined to veterinarians who are handling diseased animals, most often after a listerial abortion.

[6] L. monocytogenes is classified in the phylum Actinobacteria and is of the order Bacillales with other gram-positive, low GC content and facultative anaerobic bacteria.

In the United Kingdom, advice along these lines from the Chief Medical Officer posted in maternity clinics led to a sharp decline in cases of listeriosis in pregnancy in the late 1980s.

Studies have shown that Listex P100 is successful at eliminating L. monocytogenes from raw salmon fillet tissue, catfish fillets, fruit, surface-ripened soft cheese, hot dogs, cooked and slices of turkey breast meat, smoked salmon, mixed seafood, chocolate milk, mozzarella cheese brine, iceberg lettuce, cabbage, and sausage.

In the EU, it has stabilized at around 5 cases per annum per million population, although the rate in each country contributing data to EFSA/ECDC varies greatly.

The overall incidence of cardiac infections caused by Listeria is relatively low, with 7–10% of case reports indicating some form of heart involvement.

There is some evidence that small subpopulations of clinical isolates are more capable of colonizing the heart throughout the infection, but cardiac manifestations are usually sporadic and may rely on a combination of bacterial factors and host predispositions, as they do with other strains of cardiotropic bacteria.

[18] An outbreak of listeriosis in Canada linked to a Maple Leaf Foods plant in Toronto, Ontario killed 22 people.

[19] On September 14, 2011, the U.S. Food and Drug Administration warned consumers not to eat cantaloupes shipped by Jensen Farms from Granada, Colorado due to a potential link to a multi-state outbreak of listeriosis.

[24] A final count on December 8 put the death toll at 30: Colorado (8), Indiana (1), Kansas (3), Louisiana (2), Maryland (1), Missouri (3), Nebraska (1), New Mexico (5), New York (2), Oklahoma (1), Texas (2), and Wyoming (1).

[26] The joint investigation found that certain Blue Bell Creameries ice cream products, including bars, scoops and cookies, were the likely source for some or all of these illnesses.

Upon further investigation, the CDC said Blue Bell ice cream had evidence of Listeria bacteria in its Oklahoma manufacturing plant as far back as March 2013.

[28][26][29] On April 20, 2015, Blue Bell issued a voluntary recall of all its products, citing further internal testing that found Listeria monocytogenes in an additional half gallon of ice cream from the Brenham facility.

[39] On 2 March 2018, the New South Wales Food Authority confirmed that investigations into a listeriosis outbreak in rockmelons (cantaloupes) began in January.

[40] The cantaloupes had infected people from Victoria, Queensland, New South Wales and Tasmania, after being grown on a farm in the Riverina region of NSW.

[44] In August 2019, an outbreak was declared in several provinces in Andalusia, southern Spain, as a result of the consumption of a contaminated batch of processed meat products.

[53] On November 9, 2022, the CDC announced that Listeria in deli meats and cheeses had been linked to at least 16 cases of listeriosis, including 13 hospitalizations and 1 death.

[55] In July 2024, listeriosis was found in contaminated Silk and Walmart Great Value brand nut milks and a mandatory recall was issued.

In 2024, 6 people in the United States were hospitalized, and 3 died, due to an outbreak associated with an improperly cleaned ice cream machine used to make milkshakes at a burger restaurant.