Surveillance for foodborne-disease outbreaks--United States, 1998-2002

Since 1973, CDC has maintained a collaborative surveillance program for collection and periodic reporting of data on the occurrence and causes of foodborne-disease outbreaks (FBDOs) in the United States.

1998-2002.

The Foodborne Disease Outbreak Surveillance System reviews data on FBDOs, defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a common food. State and local public health departments have primary responsibility for identifying and investigating FBDOs. State, local, and territorial health departments use a standard form to report these outbreaks to CDC. In 1998, CDC implemented enhanced surveillance for FBDOs by increasing communication with state, local, and territorial health departments and revising the outbreak report form. Since 2001, reports of FBDOs are submitted through a web application on the Internet called the electronic Foodborne Outbreak Reporting System (eFORS).

During 1998-2002, a total of 6,647 outbreaks of foodborne disease were reported (1,314 in 1998, 1,343 in 1999, 1,417 in 2000, 1,243 in 2001, and 1,330 in 2002). These outbreaks caused a reported 128,370 persons to become ill. Among 2,167 (33%) outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (55%) and the largest percentage of cases (55%). Among bacterial pathogens, Salmonella serotype Enteritidis accounted for the largest number of outbreaks and outbreak-related cases; Listeria monocytogenes accounted for the majority of deaths of any pathogen. Viral pathogens, predominantly norovirus, caused 33% of outbreaks and 41% of cases; the proportion of outbreaks attributed to viral agents increased from 16% in 1998 to 42% in 2002. Chemical agents caused 10% of outbreaks and 2% of cases, and parasites caused 1% of outbreaks and 1% of cases.

Following implementation of measures to enhance outbreak surveillance, the annual number of FBDOs reported to CDC increased during this period compared with previous years. Viral pathogens accounted for an increased proportion of outbreaks each year during this reporting period and a higher proportion of outbreaks of known etiology during this reporting period than preceding reporting periods, probably reflecting the increased availability of improved viral diagnostic tests. S. Enteritidis continued to be a major cause of illness and L. monocytogenes was a major cause of death. In addition, multistate outbreaks caused by contaminated produce and outbreaks caused by Escherichia coli O157:H7 remained prominent.

Methods to detect FBDOs are improving, and several changes to improve the ease and timeliness of reporting FBDO data have been implemented (e.g., a revised form to simplify FBDO reporting by state health departments and improved electronic reporting methods). State and local health departments continue to investigate and report FBDOs as part of efforts to better understand and define the epidemiology of foodborne disease in the United States. At the regional and national levels, surveillance data provide an indication of the etiologic agents, vehicles of transmission, and contributing factors associated with FBDOs and help direct public health actions to reduce illness and death caused by FBDOs.