Epidemiology

Although Listeria is widespread in nature and the ingestion of Listeria monocytogenes is relatively common, the annual incidence of listeriosis among humans is low.[9] Most cases are sporadic and are reported in high-income countries; the fatality rate may be high.[10][11][12][13][14]​​​ Incidence data in low-income countries are generally not available.[15]Listeria can be isolated from the stools of up to 5% of healthy adults, and disease may be transmitted from this population.[16]

Immunocompetent patients rarely develop disseminated disease, although they may develop gastroenteritis. The pathogen has a predilection for neonates (age <1 month), adults (especially >50 years), pregnant women (30% of all patients), and immunocompromised people (with HIV/AIDS, cancer, haematological malignancies, those undergoing corticosteroid treatment, or transplant recipients).[1][17][18]​​​ Impaired cellular immunity is associated with increased incidence of the disease.

The annual incidence of laboratory-confirmed listeriosis in the United States is about 0.24 cases per 100,000 population, based on active surveillance across 10 state health departments.[19][20]​​​​​ The US Centers for Disease Control and Prevention (CDC)’s National Notifiable Disease Surveillance System receives approximately 800 confirmed cases annually.[20]​ The incidence of pregnancy-associated listeriosis is approximately 13 times higher than in the general population and nearly 25% of pregnancy-associated cases may result in miscarriage or stillbirth.[7][20]​​​​​

Intensive monitoring and recall of potentially contaminated products has decreased the prevalence of perinatal listeriosis by 44% in the US.[16]

In 2022, 30 countries in the EU/EEA reported 2770 confirmed listeriosis cases, with an age-standardised notification rate of 0.52 cases per 100,000 population. The highest rate was detected among people over 64 years old (2.1 cases per 100,000 population). The number of confirmed listeriosis cases is rising annually in the EU/EEA.[21]

In 2021, 160 listeriosis cases were reported to national surveillance in England and Wales, a 1.9% increase from the 5-year median (157 cases, 2015 to 2019). The crude incidence in 2021 was 0.27 cases per 100,000 population (95% CI 0.23 to 0.31), compared to 0.24 cases per 100,000 in 2019 (95% CI 0.21 to 0.29).[22]

In England and Wales, pregnancy-associated infections accounted for around a fifth of all reported cases in 2021 (n=34, 21.3%), higher than previous years (10.2% to 19.5% between 2012 and 2019). Of the pregnancy-associated cases, where the outcome was known (23 of 29), 79.3% of pregnancies resulted in live births and 20.7% resulted in stillbirth or miscarriage.[22]

The relative risk in the US of listeriosis is significantly higher for Hispanic people, non-Hispanic black people and non-Hispanic Asians than for non-Hispanic white people. Amongst women of childbearing age, the relative risk of listeriosis is higher in non-Hispanic Asian females and Hispanic females than in non-Hispanic white females.[23]

In 2022, a US listeriosis outbreak linked to ice cream resulted in 27 hospitalisations and one death, with CDC recommending all relevant products to be recalled.[24]​ In 2023, a US listeriosis outbreak resulting in 18 hospitalisations was linked to contaminated leafy greens in packed salads.[25]​ In 2024 outbreaks were linked to Queso Fresco and Cotija cheese (23 hospital admissions and 2 deaths), and to sliced deli meats (60 hospitalisations and 10 deaths).[26][27]

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