Incidence of Sporadic Invasive Listeriosis in the United States Remains Stable Despite Aging Population, Disproportionately Affects Some Groups (FoodNet, 2008-2023).

BACKGROUND

Listeriosis is a severe foodborne illness with elevated incidence rates among pregnant women, older adults, individuals with medical comorbidities, and certain racial and ethnic subpopulations. Foodborne Diseases Active Surveillance Network (FoodNet) data allow examination of incidence trends and differences.

METHODS

We analyze sporadic invasive listeriosis cases reported to FoodNet from 2008 to 2023. Incidence rates and rate ratios are calculated overall and by studied period, pregnancy status, age, sex, race, and ethnicity. US Census Bureau demographic projections are used to estimate incidence rate changes expected from changes in the structure of the population with time.

RESULTS

The overall incidence rate of domestically acquired sporadic listeriosis has remained stable in the FoodNet catchment area over the 15-year period, with a latest estimate (2020-2023) of 0.25 (95% confidence interval [95% CI, .22-.30) per 100 000 person-years. No significant temporal trend in any studied subpopulation is observed. Pregnant women have a 64-fold (95% CI, 47-87) higher risk when compared to non-pregnant women of reproductive age. Incidence rate in the non-pregnant population rises with age, and Hispanic, non-Hispanic Asian, and non-Hispanic Black populations have higher rates than non-Hispanic White populations. An increased overall incidence rate would have been expected because of demographic shifts; instead, the observed stable incidence rate suggests approximately 16% lower exposure to Listeria monocytogenes in 2023 compared with 2008.

CONCLUSIONS

Stable listeriosis incidence rates despite demographic shifts suggest reduced population exposure to L monocytogenes. Targeted prevention for disproportionately affected subpopulations, alongside continued efforts to reduce exposure broadly, is needed to further reduce the risk of invasive listeriosis.