Endemic, Notifiable, Bioterrorism-Related Diseases, United States, 1992-1999

Man-huei Chang, M. Kathleen Glynn, Samuel L. Groseclose


Emerging Infectious Diseases. 2003;9(5) 

In This Article

Abstract and Introduction

Little information is available in the United States regarding the incidence and distribution of diseases caused by critical microbiologic agents with the potential for use in acts of terrorism. We describe disease-specific, demographic, geographic, and seasonal distribution of selected bioterrorism-related conditions (anthrax, botulism, brucellosis, cholera, plague, tularemia, and viral encephalitides) reported to the National Notifiable Diseases Surveillance System in 1992 to 1999. Tularemia and brucellosis were the most frequently reported diseases. Anthrax, plague, western equine encephalitis, and eastern equine encephalitis were rare. Higher incidence rates for cholera and plague were noted in the western United States and for tularemia in the central United States. Overall, the incidence of conditions caused by these critical agents in the United States is low. Individual case reports should be considered sentinel events. For potential bioterrorism-related conditions that are endemic and have low incidence, the use of nontraditional surveillance methods and complementary data sources may enhance our ability to rapidly detect changes in disease incidence.

In 2001, anthrax cases associated with the intentional distribution of Bacillus anthracis spores through the postal system re-emphasized that the deliberate exposure of humans to biologic agents can happen in the United States.[1,2] Before the 2001 bioterrorism-associated anthrax events, terrorist attacks (e.g., the bombings of the World Trade Center in New York City in 1993, the Federal Building in Oklahoma City in 1995, and the Olympic Games in Atlanta in 1996; and an increase in intentional anthrax exposure hoaxes [3]) had already created substantial media and public attention because they highlighted our susceptibility to domestic terrorism, including bioterrorism. In addition, smaller focused acts of bacteriologic criminal assault had occurred in the United States, including the intentional contamination of salad bars with Salmonella organisms in 1984 in Oregon[4] and of muffins and pastries with Shigella organisms in Texas in 1996[5]; these acts served as a wake-up call announcing the threat of domestic bioterrorism. All of these events led the United States to revisit and update a national plan for bioterrorism preparedness and response in the late 1990s. In defining the role of the public health community in the detection of and response to bioterrorism, the Centers for Disease Control and Prevention (CDC) identified 10 major areas of need. One of these areas is ensuring reliable and timely disease surveillance and reporting to detect and investigate outbreaks.[6]

In response to global bioterrorism threats, CDC has proposed a list of critical biologic agents that have potential for use in a terrorist incident.[6,7,8,9] This list includes a wide range of biologic agents and prioritizes pathogens into three categories on the basis of their potential to affect the public's health, their potential for dissemination, and special needs for effective public health intervention. Prioritization of bioterrorism "threat" agents facilitates coordinated planning efforts for preparedness and response to bioterrorism at the local, state, and federal levels.

Using this guidance, public health systems can address the threat of bioterrorism by increasing healthcare sector awareness of and surveillance for these bioterrorism-related agents and the diseases they cause.[10] In the United States, public health surveillance for conditions caused by the identified critical biologic agents is conducted in multiple ways. Although data regarding these agents are reported to different national surveillance systems at CDC, no single system is specifically designed for conducting surveillance for all bioterrorism-related agents or conditions. However, many states have routinely conducted surveillance for some of these conditions and report incidence data to CDC's National Notifiable Diseases Surveillance System (NNDSS) each week ( Table 1 ).

We describe disease-specific trends in demographic characteristics and geographic and seasonal distribution of selected conditions caused by critical biologic agents reported to NNDSS. These diseases and conditions include anthrax, botulism, brucellosis, cholera, plague, tularemia, and selected viral encephalitides. By identifying patterns of endemic disease associated with critical agents, we establish a baseline against which future disease incidence can be compared. This process should allow easier identification of unusual reports of disease incidence, which in turn will enhance the ability of the public health community to identify and investigate outbreaks.


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