Anthrax postexposure prophylaxis in postal workers, Connecticut, 2001 - Bioterrorism-Related Anthrax

Emerging Infectious Diseases, Oct, 2002 by Jennifer L. Williams, Stephanie S. Noviello, Kevin S. Griffith, Heather Wurtzel, Jennifer Hamborsky, Joseph F. Perz, Ian T. Williams, James L. Hadler, David L. Swerdlow, Renee Ridzon

After inhalational anthrax was diagnosed in a Connecticut woman on November 20, 2001, postexposure prophylaxis was recommended for postal workers at the regional mail facility serving the patient's area. Although environmental testing at the facility yielded negative results, subsequent testing confirmed the presence of Bacillus anthracis. We distributed questionnaires to 100 randomly selected postal workers within 20 days of initial prophylaxis. Ninety-four workers obtained antibiotics, 68 of whom started postexposure prophylaxis, and of these, 21 discontinued. Postal workers who never started or stopped taking prophylaxis cited as reasons disbelief regarding anthrax exposure, problems with adverse events, and initial reports of negative cultures. Postal workers with adverse events reported predominant symptoms of gastrointestinal distress and headache. The influence of these concerns on adherence suggests that communication about risks of acquiring anthrax, education about adverse events, and careful management of adverse events are essential elements in increasing adherence.

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On November 20, 2001, Bacillus anthracis was confirmed in blood cultures from a 94-year-old woman in rural Oxford, Connecticut, who was diagnosed with inhalational anthrax and died 1 day later (1,2). No obvious source of exposure to B. anthracis was identified. She was the 22nd patient diagnosed with anthrax in the United States in 2001 (3). Before this case, all patients diagnosed with inhalational anthrax had had contact with intentionally contaminated mail delivered through the postal system, with the exception of a patient in New York City (where an investigation was under way). Since the source of transmission was identified as the mail for all but one anthrax case, investigation of area postal facilities began immediately.

The mail was considered a likely source of contamination for the patient in Connecticut, and postexposure antimicrobial prophylaxis was recommended for postal workers employed in the regional distribution center and local post office serving the patient's area. At the regional postal distribution center, which operates 24 h a day and employs 1,122 workers, employees work one of three 8-h shifts and process approximately 3 million pieces of mail daily.

The regional processing center contains 29 high-speed sorting machines. In contrast, the local post office, a two-room structure with 48 employees, has no high-speed sorting machines. All mail collected in the local post office is sent to the regional processing center. The post office serves two zip code areas; mail requiring sorting for the two zip codes is hand-sorted at the local level by carrier route.

The Connecticut Department of Public Health (CDPH), in consultation with the Centers for Disease Control and Prevention (CDC), recommended postexposure prophylaxis as a precaution to protect the health of the postal workers in these facilities (4). As part of a national distribution center sampling protocol, an independent contractor working for the United States Postal Service (USPS) took environmental samples on November 11, but anthrax spores had not been isolated in the regional distribution center. The decision was made to offer prophylaxis to postal workers pending the results of additional, more focused testing.

The first of many postexposure prophylaxis clinics was held on November 21, 2001. Postal workers were given an initial 10-day course of ciprofloxacin unless contraindicated (57). Nasal swabs were collected from the postal workers at the first clinics to determine if contamination was present in the facilities, rather than to diagnose or define individual exposure (8). B. anthracis was not isolated from any of 485 nasal swabs taken from postal workers.

On November 21, 25, and 28 and December 2, increasingly focused environmental sampling was performed of both the regional distribution center and the local post office to determine whether any contaminated mail had passed through the facilities (9). Samples obtained on November 21 and 25 were negative; samples taken on November 28 and December 2 from four high-speed sorting machines in the regional distribution center were positive. No contamination was identified in the local post office. Based on the positive results, the CDPH recommended that prophylaxis be extended for a full course of 60 days for all postal workers in the regional facility. Facility management conducted a progressive series of town hall meetings to notify postal employees of the test results at the various facilities, as well as results of postal worker nasal swabs. Although contaminated sorting machines were shut down for machine-specific decontamination, the regional distribution facility remained open.

Antimicrobial testing of the Connecticut patient's isolates confirmed the sensitivity of this B. anthracis strain to both doxycycline and ciprofloxacin. For the continuation phase of prophylaxis, doxycycline was offered as the primary antibiotic unless contraindications existed or the workers specifically requested to continue on ciprofloxacin.