Decreasing listeriosis mortality in the United States, 1990-2005

Abstract

Background: Listeria monocytogenes is among the most virulent foodborne pathogens, with 20% of clinical infections resulting in death. To explore listeriosis-associated mortality in the United States and to evaluate prevention efforts, we reviewed vital records over a 16-year period to assess demographic, temporal, and seasonal trends.

Methods: Nonperinatal listeriosis-associated deaths from 1990 through 2005 were identified from multiple-cause-coded death records and were combined with US census data to calculate mortality rates. Poisson regression was used to model time trends, and logistic regression was used to identify comorbid conditions associated with listeriosis on the death record.

Results: Of the 37,267,946 deaths occurring in the United States during the 16-year study period, 1178 included listeriosis on the death record. Listeriosis-related mortality rates decreased annually by 10.74% from 1990 through 1996 and by 4.26% from 1996 through 2005. Seasonal trends show a distinct peak in mortality from July through October. After adjustment for age, sex, and race/ethnicity, listeriosis was positively associated with human immunodeficiency virus (HIV) infection (odds ratio, 4.19; 95% confidence interval, 3.06-5.73), lymphoid and hematopoietic cancers (odds ratio, 5.27; 95% confidence interval, 4.47-6.22), and liver disease (odds ratio, 2.05; 95% confidence interval, 1.54-2.73) on the death record.

Conclusions: Nonperinatal listeriosis-associated deaths in the United States have decreased, paralleling a decreasing trend in incidence. Strict monitoring of food manufacturing processes, as well as improved treatment for HIV infection, may have played influential roles in preventing human infections. Health care providers should be aware of seasonal listeriosis patterns, as well as conditions predisposing individuals to severe infection and death due to L. monocytogenes infection, to guide strategies for disease management and prevention.