Background: Listeriosis is a relatively rare foodborne disease with significant public health implications. The causative pathogen, Listeria monocytogenes, grows well in refrigeration, is associated with a case-fatality rate of 20%, and causes an estimated 28% of all foodborne disease-related deaths. Nevertheless, data on the risk factors for listeriosis mortality are limited.
Methods: Using the passive surveillance listeriosis database of the County of Los Angeles Department of Public Health, we conducted a 13-year retrospective cohort study to describe nonperinatal listeriosis mortality in Los Angeles County during the period 1992-2004. A nonperinatal listeriosis case was defined as one occurring in a nonpregnant person >42 days of age who resided in Los Angeles County and had a culture positive for L. monocytogenes.
Results: Unconditional multivariable logistic regression analysis of 281 nonperinatal listeriosis cases with 29 main effects variables resulted in finding nonhematological malignancy (odds ratio [OR], 5.92; 95% confidence interval [CI], 1.85-18.9), alcoholism (OR, 4.63; 95% CI, 1.36-15.8), age 70 years (OR, 3.44; 95% CI, 1.50-7.87), steroid medication (OR, 3.34; 95% CI, 1.38-8.08), and kidney disease (OR, 2.94; 95% CI, 1.18-7.31) to be statistically significant risk factors for mortality. Other listeriosis mortality risk factors with adjusted odds ratios >1.5 included blood transfusion, asthma, black race, Asian race, use of antibiotics, hypertension, receipt of chemotherapy, and Hispanic race. Patients admitted to the hospital with a diagnosis of sepsis alone had the highest mortality (23.7%), whereas patients with cases of meningitis alone had the lowest mortality (3.13%).
Conclusions: The findings of this study should be used to help researchers and clinicians focus on specific risk factors to prevent nonperinatal listeriosis-related deaths.