| Introduction. Listeriosis is a relatively new foodborne disease with significant public health indications as the causative pathogen Listeria monocytogenes continues to grow in refrigeration, has a high case-fatality, and causes an estimated 28% of all foodborne disease related deaths. Yet, data on the incidence of listeriosis and risk factors for mortality are lacking.; Methods. A retrospective study was performed to describe the epidemiology of perinatal and non-perinatal listeriosis in Los Angeles County from 1992--2004, assess risk factors for mortality and estimate the level of underreporting. A perinatal listeriosis case was defined as a mother-fetus pair with at least one positive culture of L. monocytogenes between the two. A non-perinatal (NP) listeriosis case was defined as a non-pregnant person >42 days old with a positive culture of L. monocytogenes. California state hospital discharge data (HDD) was compared to the ACDC data to assess the completeness of reporting listeriosis. SAS 9.1 and ArcGIS were used for unconditional multivariate logistic regression and geographic mapping.; Results. With 291 NP and 122 perinatal listeriosis cases, average annual incidence rates were 2.5 NP cases per million LAC residents and 5.9 perinatal cases per 100,000 live births. NP and perinatal case-fatality were 18.6% and 32.2%, respectively. For NP case-fatality, multivariable logistic regression found kidney disease (odds ratio=2.8 (1.2--6.2)), cancer (2.8 (1.1--7.0)), and age (2.4 (1.1--5.3)) to be statistically significant risk factors, while other strong risk factors were blood transfusion (5.2 (0.7--40.4)), alcoholism (2.9 (1.0--8.5)), asthma or lung disease (2.6 (<1.0--7.1)), and steroid medication (1.7 (0.8--3.5)). Assuming the 427 listeriosis cases from the ACDC data and California HDD represented 100% of listeriosis from 1992--2003, underreporting in the ACDC data (n=386 (90%)) would have been 10%. West, South, and Alhambra health districts had the highest incidence rates of listeriosis (6.7, 6.0, and 5.7 cases per million, respectively).; Conclusion. The risk factors for disease incidence and severe outcomes, such as case-fatality, identified in this study should guide health officials in targeting high risk groups, individuals, and geographic areas to reduce the burden of listeriosis. |
