Purpose: As the demographic makeup of the United States population changes over time, with respect to ethnicity, pregnancy status, and age distribution, how is the rate of listeriosis expected to change?
Methods: Using estimated rates of listeriosis per subpopulation based on FoodNet data from 2004 to 2009, we evaluated the expected number of cases and incidence rates of listeriosis in the United States population and the pregnant women subpopulation as the demographic composition of the population changes.
Results: If the incidence rate per subpopulation is held constant, the overall United States population listeriosis incidence rate would increase from 0.25 per 100,000 (95% CI: 0.19 to 0.34) in 2010, to 0.28 (95% CI: 0.22 to 0.38) in 2020 and 0.32 (95% CI: 0.25 to 0.43) in 2030 because of the changes in population structure. The pregnancy-associated incidence rate is expected to increase from 4.0 per 100,000 pregnant women (95% CI: 2.5 to 6.5) in 2010, to 4.1 (95% CI: 2.6 to 6.7) in 2020, and 4.4 (95% CI: 2.7 to 7.2) in 2030. We further estimate that a reduction of 12% in the exposure of the population to L. monocytogenes would be needed to maintain a constant incidence rate from 2010 to 2020; assuming infectivity (strain virulence distribution and individual susceptibility) is unchanged. To reduce the overall United States population incidence rate by one third (Healthy People 2020 goal) would require a reduction in exposure (or infectivity) to L. monocytogenes of 48% over the same time period.
Significance: This information will be useful in setting public health targets, developing risk management options, and in interpreting trends in the public health burden of foodborne listeriosis in the United States.