Reduction in the incidence of invasive listeriosis in foodborne diseases active surveillance network sites, 1996-2003.

BACKGROUND: Listeriosis is a leading cause of death among patients with foodborne diseases in the United States. Monitoring disease incidence is an important element of listeriosis surveillance and control.
METHOD: We conducted population-based surveillance for Listeria monocytogenes isolates obtained from normally sterile sites at all clinical diagnostic laboratories in the Foodborne Diseases Active Surveillance Network from 1996 through 2003.
RESULTS: The incidence of laboratory-confirmed invasive listeriosis decreased by 24% from 1996 through 2003; pregnancy-associated disease decreased by 37%, compared with a decrease of 23% for patients > or =50 years old. The highest incidence was reported among Hispanic persons from 1997 through 2001. Differences in incidence by age group and ethnicity may be explained by dietary preferences.
CONCLUSION: The marked decrease in the incidence of listeriosis may be related to the decrease in the prevalence of L. monocytogenes contamination of ready-to-eat foods since 1996. The crude incidence in 2003 of 3.1 cases per 1 million population approaches the government's Healthy People objective of 2.5 cases per 1 million population by 2005. Further decreases in listeriosis incidence will require continued efforts of industry and government to reduce contamination of food and continued efforts to educate consumers and clinicians.