On October 28, 2001, a local hospital reported a suspected case of inhalational anthrax to DOH. The case-patient was a 61-year-old female with a 3-day history of progressive weakness, chest heaviness, myalgia, cough, and shortness of breath. She was admitted to intensive care with respiratory failure, emergently intubated before being interviewed, and treated with multiple antibiotics and diuretics for a presumptive diagnosis of community-acquired pneumonia, congestive heart failure, or inhalational anthrax. On October 29, nonmotile, gram-positive rods in long chains were isolated from routine blood cultures, and her antibiotic therapy was adjusted to provide for enhanced coverage of inhalational anthrax. That evening, Bacillus anthracis was preliminarily identified from her blood culture isolate and from pleural, fluid, and bronchial washings by polymerase chain reaction (PCR) at the DOH Public Health Laboratory and CDC. The following day, pleural and blood isolates were confirmed as B. anthracis by gamma phage lysis and direct fluorescent antibody testing. The case-patient died on October 31. B. anthracis isolates were subtyped at CDC by multiple-locus variable-number tandem repeat analysis (MLVA) and sequencing of the pagA gene. All isolates were MLVA genotype 62 and pagA genotype I, the same genotype as all other isolates from the 2001 anthrax outbreak in Florida, New Jersey, Washington, D.C., and Connecticut.
We report the results of the epidemiologic and environmental investigation by DOH, CDC, and local and federal law enforcement agencies in response to this isolated case of inhalational anthrax. The objectives of our investigation were to determine the time, location, and route of exposure; to identify any additional cases of cutaneous or inhalational anthrax; to determine whether this case was an isolated case or sentinel case of a larger outbreak; and to guide our public health response.
Immediately after confirming the case-patient's diagnosis, epidemiologists from DOH and CDC and a detective and special agents from the Joint Terrorism Task Force formed joint investigative teams to ensure the rapid and efficient sharing of relevant information between the epidemiologic and criminal investigations. To identify the time and location where the case-patient might have been exposed to anthrax during the 60 days before illness onset, detectives from the NYC Police Department and FBI along with local and federal epidemiologists performed joint interviews of the patient's social, work, and neighborhood contacts. We chose a 60-day period on the basis of the range of the inhalational anthrax incubation period during the Sverdlovsk anthrax outbreak in 1979. We conducted regular interagency meetings to analyze new information collaboratively and strategize about the next steps of the investigations.
We collected information about the case-patient's habits and activities through interviews with co-workers, neighbors, acquaintances, and a mail carrier to uncover any potentially relevant personal details, including places she frequented, and her social contacts. Investigators searched the case-patient's apartment, examined personal effects, reviewed telephone and financial records, and visited four post offices that she was known or thought to have used. To locate persons who might have information regarding activities during the incubation period, we displayed the case-patient's photograph in churches that she reportedly attended and in Chinatown, which she frequented. Employees from 15 businesses near the case-patient's apartment complex and work were interviewed. Members of the NYC Anthrax Investigation Team also met with investigators of the other unexplained inhalational case in Connecticut.
Using the identification number from a subway transit card issued to the case-patient by the New York City Metropolitan Transportation Authority (MTA), we obtained data about her transit activity from October 22 to October 26, indicating which buses and subway stations she entered in the week before onset of illness. The MTA also identified a previous transit card number with boarding times that matched the pattern of subway use linked to her card. Using this information, we were able to approximate her bus and subway travel during the previous month (September 21-October 20).
Our investigation included active case finding and surveillance for additional anthrax cases at the case-patient's workplace and in her apartment complex. We asked all co-workers, patients, and visitors who had spent >1 hour at her workplace during the preceding 2 weeks to report for an interview; at the interview, they were offered antibiotic prophylaxis. We also used the following information to identify additional suspect cases: 1) the hospital's employee health department list of all employees who had been evaluated for fever during the previous 2 weeks; 2) the human resources department list of employees who had missed >1 day of work during this period; 3) interviews regarding symptoms in occupants from 27 of 28 of the neighboring apartments in her complex; and 4) a community meeting in the case-patient's Bronx neighborhood in which the case was discussed and neighbors were encouraged to report illnesses or skin lesions suggestive of anthrax.
In addition, active surveillance for suspect cases was established with the U.S. Postal Service and MTA in NYC because of concern regarding potential exposures in post offices, from mail, or in the subway system. Any ill employee was contacted by DOH staff by telephone and asked about symptoms. Any suspect cases were referred for immediate evaluation and follow-up.
The case-patient was a resident of an apartment in a predominately Hispanic section of the Bronx; she lived alone. She had no known family members in NYC and a limited number of close acquaintances. A refugee from Vietnam, she had lived in the United States for 26 years. Her acquaintances at work and in her neighborhood reported her daily routine and usual activities to be habitual, with a regular work schedule, visits to Chinatown in Manhattan to shop, and trips to post offices and department stores near her workplace and home. Although reportedly friendly and generous, she lived a solitary life. Her apartment was clean and tidy. We collected no information suggesting that she had traveled outside NYC during the 60-day period before onset of illness. Neighbors did not recall any recent visitors to her home. From information received from MTA, we ascertained that she rode the No. 6 Lexington Avenue subway almost daily, traveling from her home in the Bronx to her workplace in Manhattan (Figure).
She had worked full time in an East Side Manhattan hospital for 12 years, delivering supplies from basement stockrooms to clinics and wards within the hospital. She had not missed any work in the several weeks before onset of illness. She did not directly work with or sort mail. The hospital's mail was sorted in a section of one of these stockrooms, where it was placed into wooden mail slots. The mailroom and stockroom staff reported no suspicious packages or letters.
We constructed a timeline of her activities in the several weeks preceding her illness. Although her subway transit card, work records, financial records, and sales receipts allowed us to account for some of her activities, approximately 40% of the nonwork-related hours before her death remained unaccounted for. The criminal investigation found no suspicious letters or activity to connect the case-patient to any of the known anthrax-laden postmarked letters, and no evidence existed that she had visited any of the media sites in NYC affected by this outbreak. Shared information with the investigators in Connecticut indicated that she and the case-patient in that state had little in common.
A total of 232 coworkers, occupants from 27 of 28 neighboring apartment units, 35 acquaintances, and 1,675 hospital patients and visitors were screened for symptoms of cutaneous or inhalational anthrax in connection with this single case. A total of 69 persons with respiratory symptoms and 21 with suspicious skin lesions were followed up by medical evaluation or telephone call. None of these persons were diagnosed with inhalational or cutaneous anthrax.
We contacted all hospital employees listed as ill on absentee (n=60) and employee health (n=88) lists and found them to have recovered from minor illnesses or injuries. Enhanced surveillance in NYC hospitals, the U.S. Postal Service, and emergency departments in NYC have continued since 2001 to 2003. No further cases of anthrax have been identified in NYC.