nd surveillance for potential bioterrorist events, CDC and the Council of State and Territorial Epidemiologists have recently added Q fever and reinstated tularemia to the list of nationally notifiable diseases. CDC continues to collaborate with the Council of State and Territorial Epidemiologists and state health departments to ensure that all nationally notifiable diseases caused by critical biologic agents are reportable in all states.
Caution should be exercised in interpreting specific incidence rates. Incidence rates for study diseases may also be underestimated because they were calculated on the basis of the U.S. population of all 50 states for the mid-study year of 1995, not limited to the population of reporting states for each year. Although rates might be underestimated, the patterns identified would not likely be affected. Although CDC and the Council of State and Territorial Epidemiologists have defined the standard case definitions for all nationally notifiable diseases, differences exist regarding how states interpret and apply these criteria. For example, although observed incidence rates of foodborne botulism were very high among children aged <1 year, these cases might be infant botulism reported as foodborne botulism. Therefore, standardized application of surveillance case definitions needs to be encouraged. Race and ethnicity information is incomplete in NNDSS data, potentially leading to underestimation of race- and ethnicity-specific incidence rates (44,45).
Overall, the incidence of conditions caused by critical microbiologic agents with the potential for use in acts of terrorism is low in the United States, as reported to NNDSS. Therefore, each case report should initially be considered a sentinel event requiring further investigation, especially reports from nonendemic regions of conditions with identified geographic distribution patterns. For potential bioterrorism-related conditions that are endemic and have low incidence, nontraditional surveillance methods (e.g., sentinel emergency department surveillance ) and complementary data sources (e.g., electronic laboratory reporting ) might be used to complement traditional sources of surveillance data (e.g., NNDSS) and can enhance our ability to detect changes in disease incidence.
Ms. Chang is an epidemiologist with the Surveillance Systems Branch, Division of Public Health Surveillance and Informatics, Epidemiology program Office, at the Centers for Disease Control and Prevention. Her research interests include traditional surveillance, bioterrorism syndromic surveillance, and aberration detection methods.
We thank the U.S. state and territorial health departments that conduct notifiable disease surveillance; the Bioterrorism Preparedness and Response Program, National Center for Infectious Disease, Centers for Disease Control and Prevention, for providing assistance and consultation; Ruth Ann Jajosky for comments and suggestions; and John D. Hatmaker for his technical support.
- Centers for Disease Control and Prevention. Update: investigation of bioterrorism-related anthrax and interim guidelines for clinical evaluation of persons with possible anthrax. MMWR Morb Mortal Wkly Rep. 2001;50:941–8.
- Jernigan JA, Stephens DS, Ashford DA, Omenaca C, Topiel MS, Galbraith M, Bioterrorism-related inhalational anthrax: the first 10 cases reported in the United States. Emerg Infect Dis. 2001;7:933–44.
- Centers for Disease Control and Prevention. Bioterrorism alleging use of anthrax and interim guidelines for management—United States, 1998. MMWR Morb Mortal Wkly Rep. 1998;48:69–74.
- Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R, Mauvais S, A large community outbreak of salmonellosis caused by intentional contamination of restaurant salad bars. JAMA. 1997;278:389–95.
- Kolavic SA, Kimura A, Simons SL, Slutsker L, Barth S, Haley CE. An outbreak of Shigella dysenteriae type 2 among laboratory workers due to intentional food contamination. JAMA. 1997;278:396–8.
- LeDuc JM, Ostroff SM, McDade JE, Lillibridge S, Hughes JM. The role of the public heal