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Update: Investigation of Bioterrorism-Related Anthrax --- Connecticut, 2001

CDC and state and local health departments continue investigating cases of bioterrorism-related anthrax. This report revises the number of suspected cases and updates the investigation of a 94-year-old Connecticut (CT) resident who died from inhalational anthrax.

As of December 5, a total of 22 cases of anthrax have been identified; 11 were confirmed as inhalational anthrax, and 11 (seven confirmed and four suspected) were cutaneous. A 54-year-old man who lived in Delaware and who worked at a postal facility in New Jersey (NJ) previously had been classified as having a suspected case of cutaneous anthrax. Additional laboratory findings indicate that the patient's illness no longer meets the CDC surveillance case definition for anthrax (1). Initially, he was classified as having a suspected case because of a lesion on his left hand and elevated levels of antibody (IgG) to the protective antigen component of anthrax toxin. Subsequent biopsies of the skin lesion did not reveal Bacillus anthracis in the tissue, and additional confirmatory antibody tests on serum specimens were negative.

The investigation in CT has not identified any additional cases of anthrax through prospective and retrospective surveillance. For prospective surveillance, hospitals, clinicians, postal facilities, and the state medical examiner have been asked to report daily any persons with clinical findings that might be related to anthrax, including sepsis and pneumonia. To date, 50 such patients have been reported. No evidence of anthrax was found in 43 patients and the remaining seven are being evaluated; preliminary investigations of the seven patients have not identified evidence of anthrax. Retrospective surveillance has included a review of all deaths since September 1 involving residents of Oxford and eight surrounding towns (Beacon Falls, Naugatuck, Ansonia, Derby, Woodbury, Shelton, Seymour, and Southbury [total population: 152,481]); 487 death certificates for persons who died during September--November 2001 have been reviewed. Of the 131 deaths attributed to sepsis, pneumonia, sudden death, respiratory arrest, cardiac arrest, or undetermined cause, 66 occurred in hospitals. Of these, 52 had no apparent anthrax disease. For 14 persons who died soon after arrival to the hospital, review of hospital records revealed no evidence of anthrax, but information in the hospital record was insufficient to determine the specific cause of death, and postmortem examinations were not conducted.

The source of exposure for the case of inhalational anthrax in a 94-year-old woman who lived in Oxford, CT, remains unknown. Multiple environmental samples collected from all places (e.g., the patient's home, church, voting place, restaurants, and cars in which she traveled) the patient was known to have visited during the 60 days preceding illness onset were negative for B. anthracis by culture. Nasal swab specimens were negative from 16 persons epidemiologically linked to the case (e.g., persons who worked in the home and assisted with shopping).

Environmental sampling was performed at the postal processing and distribution center in Wallingford, CT, that serves the towns of Oxford and Seymour and identified B. anthracis spores in three high-speed mail sorters. This facility receives mail from several postal distribution facilities known to have been contaminated by B. anthracis spores, including the postal center in Hamilton, NJ, which was the origination site for envelopes containing B. anthracis powder that were addressed to two U.S. senators. To evaluate potential cross-contamination of envelopes (i.e., an envelope contaminated from another B. anthracis-contaminated envelope or environmental surface), postal sorting records from the Wallingford facility are being examined to determine the timing and pathways of mail delivered to the CT patient and her local relatives and contacts. Sorting records in Hamilton indicated that an envelope addressed to a postal code adjacent to Oxford had been processed using the same automatic canceling machine at Hamilton <1 minute after one of the two B. anthracis powder-containing letters sent to a U.S. senator. This envelope was subsequently sorted at Wallingford and delivered to Seymour. The envelope was received at a residence 4 miles from the home of the CT patient; this envelope was recovered from the recipient and B. anthracis spores were detected on the outside of the envelope; none of the members of this household had clinical evidence of anthrax. No record of mail to the CT case-patient processed at Hamilton was found, and no B. anthracis spores have been recovered from envelopes found at her home.

Reported by: N Lustig, MPH, Pomperaug Health District, Oxford; K Spargo, MPH, Naugatuck Valley Health District, Shelton; W Carver, MD, Office of the Chief Medical Examiner, M Cartter, MD, J Garcia, MD, DM Barden, MT (HHS), DR Mayo, ScD, KA Kelley, DrPH, J Hadler, MD, State Epidemiologist, Connecticut Dept of Public Health. G DiFerdinando, MD, E Bresnitz, MD, State Epidemiologist, New Jersey Dept of Health and Senior Svcs. L Hathcock, PhD, State Epidemiologist, Delaware Div of Public Health. EIS officers, CDC.

Editorial Note:

As of December 5, a total of 11 inhalational anthrax cases have been identified; direct exposure to a B. anthracis-containing envelope was likely in the first nine cases (2). The source of exposure to B. anthracis for the inhalational anthrax cases in CT and New York City (NYC) remain under investigation by public health and law enforcement officials. No direct exposure to B. anthracis-containing envelopes has been identified for these cases. Similar to the first nine cases of inhalational anthrax, exposure to B. anthracis might have occurred through the mail from exposure to an envelope containing B. anthracis powder. No direct exposure to envelopes containing B. anthracis powder has been identified for the inhalational cases in CT and NYC. In the absence of definitive evidence indicating how transmission occurred, infection from a cross-contaminated envelope is one hypothesis being considered by investigators.

Cross-contamination could explain how B. anthracis spores were spread to some postal facilities that did not process the envelopes addressed to the U.S. senators. Approximately 85 million pieces of mail were processed on the days after the implicated envelopes passed through the NJ and the District of Columbia (DC) sorting facilities until they were closed. Both of these facilities had evidence of widespread environmental contamination with B. anthracis. Some of the pieces of mail that passed through these facilities could have been cross-contaminated and, in turn, could have contaminated mail processing equipment or other envelopes processed elsewhere. Despite the high volume of mail distributed to metropolitan areas around these facilities, active surveillance has not identified cases of inhalational anthrax among approximately 10.5 million residents in NJ, DC, Pennsylvania, Maryland, and Virginia or in postal workers since the initial cluster of cases associated with the processing of the implicated letters sent to the U.S. senators. The large population, the duration of active surveillance, and the absence of additional cases of inhalational anthrax indicate that if there is a risk for inhalational anthrax associated with exposure to mail cross-contaminated by the letters addressed to the U.S. senators, it is very low.

Despite this very low risk, persons remaining concerned about their risk may want to take additional steps such as not opening suspicious mail; keeping mail away from your face when you open it and not blowing or sniffing mail or mail contents; washing your hands after you handle the mail; avoiding vigorous handling of mail, such as tearing or shredding mail before disposal; and discarding envelopes after opening mail. However, the effectiveness of these steps in reducing any residual risk is not known.

Suspicious persons or situations should be reported to law enforcement authorities. Health-care providers should remain alert for persons with clinical presentations consistent with early anthrax (3), obtain appropriate diagnostic tests (e.g., blood cultures and chest radiograph) (4), and report suspicious illnesses to local or state public health authorities. Fatalities can be minimized by promptly initiating combination antimicrobial therapy (5). Recommendations for risk reduction for persons with potential occupational exposure are available (6). Public health surveillance for anthrax and research efforts to further define the risk associated with exposure to B. anthracis in the environment as a result of the bioterrorist attack is ongoing. CDC will continue to provide updates as new information becomes available.


  1. CDC. Update: investigation of anthrax associated with intentional exposure and interim public health guidelines, October 2001. MMWR 2001;50:889--93.
  2. CDC. Update: investigation of bioterrorism-related inhalational anthrax---Connecticut, 2001. MMWR 2001;50:1049--51.
  3. Jernigan JA, Stephens DS, Ashford DA, et al. Bioterrorism-related inhalational anthrax: the first 10 cases reported in the United States. Emerg Infect Dis 2001;7:933--44.
  4. CDC. Update: investigation of bioterrorism-related anthrax and interim guidelines for clinical evaluation of persons with possible anthrax. MMWR 2001;50:941--8.
  5. CDC. Update: investigation of bioterrorism-related anthrax and interim guidelines for exposure management and antimicrobial therapy, October 2001. MMWR 2001;50:909--19.
  6. CDC. Interim recommendations for protecting workers from exposure to Bacillus anthracis in work sites in which mail is handled or processed. MMWR 2001;50:961.

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