Listeriosis

Listeriosis is a bacterial infection most commonly caused by Listeria monocytogenes, although L. ivanovii and L. grayi have been reported in certain cases. It is classified as a foodborne illness and manifests in two principal forms: a non-invasive gastrointestinal presentation and a more severe invasive systemic infection. The organism is ubiquitous in nature, being found in soil, water, and the digestive tracts of various animals, which creates multiple potential pathways for food contamination.

The clinical spectrum of listeriosis ranges from mild, self-limiting gastroenteritis to life-threatening systemic infection. Noninvasive listeriosis, characterized as febrile listerial gastroenteritis, typically presents with diarrhea, fever, headache, and muscle aches following a short incubation period of a few days, primarily affecting otherwise healthy individuals. Invasive listeriosis is a severe form in which bacteria spread from the intestines to the bloodstream or other body sites, potentially causing severe sepsis, meningitis, or encephalitis, sometimes resulting in lifelong harm or death. In pregnant women, infection may result in stillbirth, spontaneous abortion, or preterm birth, though mothers usually survive. The disease may manifest up to two months after consuming contaminated food.

Listeriosis is a relatively rare disease with an incidence ranging from 0.1 to 10 cases per million people per year, varying considerably across countries and regions. Although the absolute number of cases is small, the high mortality rate associated with this infection—estimated at 20-30% overall and resulting in fetal loss or neonatal death in approximately 22% of pregnancy-related cases—makes it a substantial public health concern. Outbreaks have occurred worldwide and have been associated with a variety of food products, including ready-to-eat meat products, dairy products such as soft cheeses and unpasteurized milk, smoked fish, and fresh produce including vegetables and prepared salads.

The primary route of infection is ingestion of food contaminated with high numbers of Listeria monocytogenes. The bacterium's ability to survive and multiply at low temperatures typically found in refrigerators distinguishes it from many other foodborne pathogens and complicates food safety management. Contamination of vegetables may occur through soil or the use of animal manure as fertilizer, while ready-to-eat foods may become contaminated during processing, with bacterial multiplication occurring during distribution and storage. Vertical transmission from pregnant women to unborn babies represents an important secondary route, though human-to-human transmission otherwise remains uncommon.

The primary populations at elevated risk for severe listeriosis include pregnant women and their fetuses or newborns, elderly adults, and individuals with weakened immune systems due to underlying conditions or immunosuppressive therapy. These groups should receive targeted food safety guidance emphasizing avoidance of high-risk foods and strict adherence to safe food handling practices. While rare, severe illness can occasionally occur in persons without these recognized risk factors, underscoring the pathogen's potential virulence.

Control of Listeria requires an integrated approach across all stages of the food chain, including implementation of Good Hygienic Practices, Good Manufacturing Practices, and food safety management systems based on Hazard Analysis Critical Control Point principles. Pasteurization and thorough cooking effectively kill Listeria, making these critical control measures for food safety. Persons in high-risk groups should adhere to specific guidance including respecting shelf-life and storage temperatures on ready-to-eat food labels, avoiding unpasteurized dairy products and certain soft cheeses, and reheating ready-to-eat foods until steaming hot before consumption.

Surveillance for listeriosis requires heightened clinical awareness given the severity of outcomes in vulnerable populations and the potentially prolonged incubation period of up to two months, which can complicate outbreak source attribution. The disease's rarity combined with its high fatality ratio means each case warrants thorough investigation to identify potential food sources and prevent additional cases. Laboratory confirmation requires isolation of the organism from blood or cerebrospinal fluid, and early diagnosis is essential for effective treatment, particularly in pregnant women where prompt antibiotic therapy can prevent fetal or neonatal infection.

1. 1 WHO Fact Sheet. Listeriosis.
2. 2 WHO Q&A. News.
3. 3 Wikidata. listeriosis.
4. 4 Wikipedia. Listeriosis - Wikipedia.

ICD-10

ICD-11

Total cases

3K

Peak month

2023-08

Coverage

2 reporting countries · 2000-01-01 → 2026-05-09