Bioterrorism-related inhalational anthrax in an elderly woman, Connecticut, 2001 - Research

Emerging Infectious Diseases, June, 2003 by Kevin S. Griffith, Paul Mead, Gregory L. Armstrong, John Painter, Katherine A. Kelley, Alex R. Hoffmaster, Donald Mayo, Diane Barden, Renee Ridzon, Umesh Parashar, Eyasu Habtu Teshale, Jennifer Williams, Stephanie Noviello, Joseph F. Perz, Eric E. Mast, David L. Swerdlow, James L. Hadler

On November 20, 2001, inhalational anthrax was confirmed in an elderly woman from rural Connecticut. To determine her exposure source, we conducted an extensive epidemiologic, environmental, and laboratory investigation. Molecular subtyping showed that her isolate was indistinguishable from isolates associated with intentionally contaminated letters. No samples from her home or community yielded Bacillus anthracis, and she received no first-class letters from facilities known to have processed intentionally contaminated letters. Environmental sampling in the regional Connecticut postal facility yielded B. anthracis spores from 4 (31%) of 13 sorting machines. One extensively contaminated machine primarily processes bulk mail. A second machine that does final sorting of bulk mail for her zip code yielded B. anthracis on the column of bins for her carrier route. The evidence suggests she was exposed through a cross-contaminated bulk mail letter. Such cross-contamination of letters and postal facilities has implications for managing the response to future B. anthracis-contaminated mailings.

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On November 19, 2001, a suspected case of inhalational anthrax in a 94-year-old woman was reported to the Connecticut Department of Public Health (CTDPH) (1-3). This was the first case of Bacillus anthracis infection reported to the CTDPH since 1968 and the eleventh inhalational anthrax case in the United States since October 4, 2001 (1-6). The patient's symptoms of fever, fatigue, malaise, dry cough, and shortness of breath began 20 days after the last confirmed inhalational anthrax patient became ill and 36 days after the last known intentionally contaminated letters, addressed to U.S. Senators Thomas Daschle and Patrick Leahy, were postmarked in Trenton, New Jersey (1-4) (Figure 1).The patient in Connecticut was not in the known categories of intentionally contaminated letter recipients and was not a postal worker or a mailhandler (1,5). This report describes the epidemiologic and environmental investigation conducted to determine whether her case was related to the other bioterrorism-related cases; whether she was the only case in Connecticut or a sentinel of a larger outbreak; and the source, place, and time of her exposure. The clinical aspects of the case have been described (2,3).

Methods

Isolate Comparison

A subculture of the patient's B. anthracis blood culture isolate was examined for species confirmation, antibiotic susceptibility testing, and molecular subtyping by multiple-locus variable-number tandem repeat analysis, which examines eight loci on the B. anthracis genome (7,8). The isolate was compared with previous bioterrorism-related isolates on the basis of antibiotic susceptibilities and molecular subtyping.

Surveillance

We conducted retrospective surveillance for additional cases of human or animal anthrax in Connecticut for September 1 to November 30, 2001, by using data from death certificates; medical examiner, laboratory, and postal worker absentee records; and surveys of licensed veterinarians. We conducted prospective surveillance for additional cases of human or animal anthrax in Connecticut from November 20 to December 21, 2001, by using reports from hospital admissions, laboratories, healthcare providers, veterinarians, and animal control officers, and also reports from the U.S. Postal Service (USPS) on employee absenteeism (9,10).

Patient Epidemiologic Investigation

In collaboration with local, state, and federal law enforcement agencies, we identified the patient's activities, home visitors, and all places she visited in the 60 days preceding her symptom onset using her personal calendar and interviewing her family, friends, neighbors, physicians, and persons who cleaned her home. We also met with investigators of the 10th inhalational anthrax case from New York City to assess similarities between the two cases.

Patient Environmental Investigation

In the patient's home, environmental samples and selected personal effects were collected for culture during eight inspections conducted from November 20 to December 4. We obtained swab and wipe samples from clean, nonporous surfaces and vacuum samples from large or dusty nonporous or porous surfaces (11). Surface swab samples were collected by using synthetic swabs moistened with sterile saline or sterile water to sample such surfaces as vents; furniture; appliances, including vacuum cleaners; areas with dust; electrostatically charged surfaces, including a television screen; aerosolizing and misting devices, including an inhaler and a perfume bottle; and all places in the home where she might have handled her mail. Vacuum samples were collected by using high-efficiency particulate air (HEPA) vacuum cleaners equipped with a filter collection device to vacuum carpets, furniture, and clothing. Final intensified sampling was performed by using blowers to aerosolize particles throughout the living space, followed by air sampling that used high-volume air filtration devices and the placement of blood agar settle plates throughout the home. Personal effects collected from the home included pieces of mail, file folders, pieces of paper, used tissues, letter openers, pill bottles, an inhaler, photographs, and a calendar. Bulk samples of contents from the bags of vacuum cleaners normally used to clean the home were collected for culture. Nasal swabs were taken from all persons who spent >60 minutes in the patient's home during the 60 days before onset of her symptoms.