Public health in the time of bioterrorism - Bioterrorism-Related Anthrax

Emerging Infectious Diseases, Oct, 2002 by Bradley A. Perkins, Tanja Popovic, Kevin Yeskey

On Thursday, October 4, 2001, just 24 days after the tragic events of September 11, the Florida Department of Health and the Centers for Disease Control and Prevention (CDC) confirmed the first case of inhalational anthrax in the United States in more than 25 years. Recognition of this unexpected case is attributed to the alertness of local infectious disease physician Larry Bush, who promptly notified Jean Malecki, director, Palm Beach County Health Department (1,2). By Saturday, October 6, a team of federal, state, and local public health and local law enforcement investigators identified intentional Bacillus anthracis spore contamination at the patient's workplace. These events marked the beginning of the first U.S. outbreak of bioterrorism-related anthrax and (for many of us in clinical medicine, public health, and law enforcement) ushered in the transition from tabletop bioterrorism exercises to real-world investigation and response.

Contingency plans to mitigate bioterrorism-related anthrax outbreaks go back to August 1998, when CDC hosted the "Workshop on Improving Public Health Response to Possible Acts of Bioterrorism." This workshop brought together state and local health departments, public health professional organizations, the U.S. Department of Defense, and the U.S. Department of Justice to examine ways of improving public health preparedness for bioterrorism (CDC, unpub. data). Two investments made as a result of this workshop were the Laboratory Response Network for Bioterrorism and the National Pharmaceutical Stockpile. These early investments were key components of the public health response to the 2001 bioterrorism-related anthrax outbreak.

The Laboratory Response Network was created at the recommendation of the 1998 Workshop's "Diagnosis Working Group," the then Association of State and Territorial Public Health Laboratories (now Association for Public Health Laboratories), and CDC. The Laboratory Response Network is a tiered system of laboratories with capacities defined in an A (lowest tier) through D (highest) pyramid structure (3,4). In support of this structure, procedures for identification of B. anthracis, and other Category A biologic agents, were validated, and in some instances developed (or redeveloped) de novo on the basis of older methods. Protocols were written into standard laboratory procedure manuals. Reagents for testing were standardized, produced, and distributed by CDC to participating laboratories. State health department laboratory scientists were trained to use these methods for identifying B. anthracis, Yersinia pestis (causative agent of plague), and Francisella tularensis (causative agent of tularemia) in the fall and winter of 2000. Capacity for specialized or more developmental diagnostic and other tests for B. anthracis (e.g., real time polymerase chain reaction [PCR] [5], direct fluorescent-antibody assay [6], immunohistochemical testing, molecular subtyping [7], and antimicrobial susceptibility testing [8]) were established at CDC and (in some instances) at a small number of other advanced U.S. laboratories (e.g., U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona). For serologic testing, which was found to be invaluable in identifying anthrax cases during the investigation, existing tests developed for vaccine evaluation were adapted for diagnostic purposes (9). All these laboratory measures were in place before the 2001 anthrax outbreak.

During the acute phase of the outbreak, Laboratory Response Network laboratories processed >121,700 specimens for B. anthracis (the bulk from environmental specimens from areas of suspected or confirmed contamination). Public Health Laboratories (other than CDC) tested 84,000 (69%) specimens; the Department of Defense tested 30,200 (25%) specimens; and CDC tested 7,500 (6%) (CDC, unpub. data). Handling the unusual surge of demand without the support of the Laboratory Response Network is difficult to imagine and would have likely compromised the investigation.

The National Pharmaceutical Stockpile was another investment made as a result of the 1998 Workshop and put in place before the 2001 outbreak. During the outbreak, the pharmaceutical stockpile team transported not only antibiotics, anthrax vaccine, clinical and environmental samples, and B. anthracis isolates but also epidemiologists, laboratory scientists, pathologists, and specialized teams of researchers. Under extreme pressure, the team made 143 sorties to 9 states and delivered 3.75 million antibiotic tablets from October 8, 2001 to January 11, 2002 (CDC, NPS Program Logistics Log, Oct 2001-Jan 2002).

Other earlier public health investments that paid off during the anthrax outbreak investigation were CDC's more than 50-year-old applied epidemiology training program, Epidemic Intelligence Service, and other academic, state and local health department, and CDC efforts to develop the seasoned cadre of field epidemiologists (10,11) that make up the core of public health investigation and response. These epidemiologists, who work in established networks and make up and often lead complex partnerships, comprise the public health front lines of the bioterrorism response team.