In October 2001, four cases of inhalational anthrax occurred in workers in a Washington, D.C., mail facility that processed envelopes containing Bacillus anthracis spores. We reviewed the envelopes’ paths and obtained exposure histories and nasal swab cultures from postal workers. Environmental sampling was performed. A sample of employees was assessed for antibody concentrations to B. anthracis protective antigen. Case-patients worked on nonoverlapping shifts throughout the facility. Environmental sampling showed diffuse contamination of the facility, suggesting multiple aerosolization events. Potential workplace exposures were similar for the case-patients and the sample of workers. All nasal swab cultures and serum antibody tests were negative. Available tools could not identify subgroups of employees at higher risk for exposure or disease. Prophylaxis was necessary for all employees. To protect postal workers against bioterrorism, measures to reduce the risk of occupational exposure are necessary.
bioterrorism; Bacillus anthracis; postal facility; inhalational anthrax
In October 2001, the first inhalational anthrax case in the United States since 1976 was identified in a media company worker in Florida. A national investigation was initiated to identify additional cases and determine possible exposures to Bacillus anthracis. Surveillance was enhanced through health-care facilities, laboratories, and other means to identify cases, which were defined as clinically compatible illness with laboratory-confirmed B. anthracis infection. From October 4 to November 20, 2001, 22 cases of anthrax (11 inhalational, 11 cutaneous) were identified; 5 of the inhalational cases were fatal. Twenty (91%) case-patients were either mail handlers or were exposed to worksites where contaminated mail was processed or received. B. anthracis isolates from four powder-containing envelopes, 17 specimens from patients, and 106 environmental samples were indistinguishable by molecular subtyping. Illness and death occurred not only at targeted worksites, but also along the path of mail and in other settings. Continued vigilance for cases is needed among health-care providers and members of the public health and law enforcement communities.
From October 4 to November 2, 2001, the first 10 confirmed cases of inhalational anthrax caused by intentional release of Bacillus anthracis were identified in the United States. Epidemiologic investigation indicated that the outbreak, in the District of Columbia, Florida, New Jersey, and New York, resulted from intentional delivery of B. anthracis spores through mailed letters or packages. We describe the clinical presentation and course of these cases of bioterrorism-related inhalational anthrax. The median age of patients was 56 years (range 43 to 73 years), 70% were male, and except for one, all were known or believed to have processed, handled, or received letters containing B. anthracis spores. The median incubation period from the time of exposure to onset of symptoms, when known (n=6), was 4 days (range 4 to 6 days). Symptoms at initial presentation included fever or chills (n=10), sweats (n=7), fatigue or malaise (n=10), minimal or nonproductive cough (n=9), dyspnea (n=8), and nausea or vomiting (n=9). The median white blood cell count was 9.8 X 10(3)/mm(3) (range 7.5 to 13.3), often with increased neutrophils and band forms. Nine patients had elevated serum transaminase levels, and six were hypoxic. All 10 patients had abnormal chest X-rays; abnormalities included infiltrates (n=7), pleural effusion (n=8), and mediastinal widening (seven patients). Computed tomography of the chest was performed on eight patients, and mediastinal lymphadenopathy was present in seven. With multidrug antibiotic regimens and supportive care, survival of patients (60%) was markedly higher (<15%) than previously reported.
The lack of identified exposures in 2 of the 11 cases of bioterrorism-related inhalation anthrax in 2001 raised uncertainty about the infectious dose and transmission of Bacillus anthracis. We used the Wells-Riley mathematical model of airborne infection to estimate 1) the exposure concentrations in postal facilities where cases of inhalation anthrax occurred and 2) the risk for infection in various hypothetical scenarios of exposure to B. anthracis aerosolized from contaminated mail in residential settings. These models suggest that a small number of cases of inhalation anthrax can be expected when large numbers of persons are exposed to low concentrations of B. anthracis. The risk for inhalation anthrax is determined not only by bacillary virulence factors but also by infectious aerosol production and removal rates and by host factors.
Anthrax; Air microbiology; Infection; Risk; Inhalation exposure; Lethal Dose 50; Ventilation
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.
Bacillus anthracis; inhalational anthrax; bioterrorism; postal facilities; research
On October 31, 2001, in New York City, a 61-year-old female hospital employee who had acquired inhalational anthrax died after a 6-day illness. To determine sources of exposure and identify additional persons at risk, the New York City Department of Health, Centers for Disease Control and Prevention, and law enforcement authorities conducted an extensive investigation, which included interviewing contacts, examining personal effects, summarizing patient’s use of mass transit, conducting active case finding and surveillance near her residence and at her workplace, and collecting samples from co-workers and the environment. We cultured all specimens for Bacillus anthracis. We found no additional cases of cutaneous or inhalational anthrax. The route of exposure remains unknown. All environmental samples were negative for B. anthracis. This first case of inhalational anthrax during the 2001 outbreak with no apparent direct link to contaminated mail emphasizes the need for close coordination between public health and law enforcement agencies during bioterrorism-related investigations.
B. anthracis; inhalational anthrax; bioterrorism; research
On November 19, 2001, a case of inhalational anthrax was identified in a 94-year-old Connecticut woman, who later died. We conducted intensive surveillance for additional anthrax cases, which included collecting data from hospitals, emergency departments, private practitioners, death certificates, postal facilities, veterinarians, and the state medical examiner. No additional cases of anthrax were identified. The absence of additional anthrax cases argued against an intentional environmental release of Bacillus anthracis in Connecticut and suggested that, if the source of anthrax had been cross-contaminated mail, the risk for anthrax in this setting was very low. This surveillance system provides a model that can be adapted for use in similar emergency settings.
On November 11, 2001, following the bioterrorism-related anthrax attacks, the U.S. Postal Service collected samples at the Southern Connecticut Processing and Distribution Center; all samples were negative for Bacillus anthracis. After a patient in Connecticut died from inhalational anthrax on November 19, the center was sampled again on November 21 and 25 by using dry and wet swabs. All samples were again negative for B. anthracis. On November 28, guided by information from epidemiologic investigation, we sampled the site extensively with wet wipes and surface vacuum sock samples (using HEPA vacuum). Of 212 samples, 6 (3%) were positive, including one from a highly contaminated sorter. Subsequently B. anthracis was also detected in mail-sorting bins used for the patient’s carrier route. These results suggest cross-contaminated mail as a possible source of anthrax for the inhalational anthrax patient in Connecticut. In future such investigations, extensive sampling guided by epidemiologic data is imperative.
Bacillus anthracis; anthrax; environmental sampling; postal facility; surface sampling; HEPA vacuum sock; swabs; wipes
After public notification of confirmed cases of bioterrorism-related anthrax, the Centers for Disease Control and Prevention’s Emergency Operations Center responded to 11,063 bioterrorism-related telephone calls from October 8 to November 11, 2001. Most calls were inquiries from the public about anthrax vaccines (58.4%), requests for general information on bioterrorism prevention (14.8%), and use of personal protective equipment (12.0%); 882 telephone calls (8.0%) were referred to the state liaison team for follow-up investigation. Of these, 226 (25.6%) included reports of either illness clinically confirmed to be compatible with anthrax or direct exposure to an environment known to be contaminated with Bacillus anthracis. The remaining 656 (74.4%) included no confirmed illness but reported exposures to “suspicious” packages or substances or the receipt of mail through a contaminated facility. Emergency response staff must handle high call volumes following suspected or actual bioterrorist attacks. Standardized health communication protocols that address contact with unknown substances, handling of suspicious mail, and clinical evaluation of suspected cases would allow more efficient follow-up investigations of clinically compatible cases in high-risk groups.
anthrax; bioterrorism; triage; Centers for Disease Control and Prevention
We used unpublished reports, published manuscripts, and communication with investigators to identify and summarize 49 anthrax-related epidemiologic field investigations conducted by the Centers for Disease Control and Prevention from 1950 to August 2001. Of 41 investigations in which Bacillus anthracis caused human or animal disease, 24 were in agricultural settings, 11 in textile mills, and 6 in other settings. Among the other investigations, two focused on building decontamination, one was a response to bioterrorism threats, and five involved other causes. Knowledge gained in these investigations helped guide the public health response to the October 2001 intentional release of B. anthracis, especially by addressing the management of anthrax threats, prevention of occupational anthrax, use of antibiotic prophylaxis in exposed persons, use of vaccination, spread of B. anthracis spores in aerosols, clinical diagnostic and laboratory confirmation methods, techniques for environmental sampling of exposed surfaces, and methods for decontaminating buildings.
anthrax; Bacillus anthracis; bacterial infections; disease outbreaks; public health; bioterrorism; Centers for Disease Control and Prevention (U.S.); historical article (publication type); zoonoses
The index case of inhalational anthrax in October 2001 was in a man who lived and worked in Florida. However, during the 3 days before illness onset, the patient had traveled through North Carolina, raising the possibility that exposure to Bacillus anthracis spores could have occurred there. The rapid response in North Carolina included surveillance among hospital intensive-care units, microbiology laboratories, medical examiners, and veterinarians, and site investigations at locations visited by the index patient to identify the naturally occurring or bioterrorism-related source of his exposure.
Bacillus anthracis; anthrax; bioterrorism; epidemiology and surveillance
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 21 discontinued. Postal workers who stopped or never started 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.
Anthrax; Bacillus anthracis; prophylaxis; adverse effects; ciprofloxacin; doxycycline; patient noncompliance; Connecticut
At least four Bacillus anthracis–containing envelopes destined for New York City and Washington, D.C., were processed at the Trenton Processing and Distribution Center (PDC) on September 18 and October 9, 2001. When cutaneous anthrax was confirmed in a Trenton postal worker, the PDC was closed. Four cutaneous and two inhalational anthrax cases were identified. Five patients were hospitalized; none died. Four were PDC employees; the others handled or received mail processed there. Onset dates occurred in two clusters following envelope processing at the PDC. The attack rate among the 170 employees present when the B. anthracis–containing letters were sorted on October 9 was 1.2%. Of 137 PDC environmental samples, 57 (42%) were positive. Five (10%) of 50 local post offices each yielded one positive sample. Cutaneous or inhalational anthrax developed in four postal employees at a facility where B. anthracis–containing letters were processed. Cross-contaminated mail or equipment was the likely source of infection in two other case-patients with cutaneous anthrax.
Bacillus anthracis; anthrax; bioterrorism
On October 12, 2001, two envelopes containing Bacillus anthracis spores passed through a sorting machine in a postal facility in Washington, D.C. When anthrax infection was identified in postal workers 9 days later, the facility was closed. To determine if exposure to airborne B. anthracis spores continued to occur, we performed air sampling around the contaminated sorter. One CFU of B. anthracis was isolated from 990 L of air sampled before the machine was activated. Six CFUs were isolated during machine activation and processing of clean dummy mail. These data indicate that an employee working near this machine might inhale approximately 30 B. anthracis-containing particles during an 8-h work shift. What risk this may have represented to postal workers is not known, but the risk is approximately 20-fold less than estimates of sub-5 micron B. anthracis-containing particles routinely inhaled by asymptomatic, unvaccinated workers in a goat-hair mill.
Bacillus anthracis; anthrax; risk assessment; occupational exposure
Bacillus anthracis infection is rare in developed countries. However, recent outbreaks in the United States and Europe and the potential use of the bacteria for bioterrorism have focused interest on it. Furthermore, although anthrax was known to typically occur as one of three syndromes related to entry site of (i.e., cutaneous, gastrointestinal, or inhalational), a fourth syndrome including severe soft tissue infection in injectional drug users is emerging. Although shock has been described with cutaneous anthrax, it appears much more common with gastrointestinal, inhalational (5 of 11 patients in the 2001 outbreak in the United States), and injectional anthrax. Based in part on case series, the estimated mortalities of cutaneous, gastrointestinal, inhalational, and injectional anthrax are 1%, 25 to 60%, 46%, and 33%, respectively. Nonspecific early symptomatology makes initial identification of anthrax cases difficult. Clues to anthrax infection include history of exposure to herbivore animal products, heroin use, or clustering of patients with similar respiratory symptoms concerning for a bioterrorist event. Once anthrax is suspected, the diagnosis can usually be made with Gram stain and culture from blood or surgical specimens followed by confirmatory testing (e.g., PCR or immunohistochemistry). Although antibiotic therapy (largely quinolone-based) is the mainstay of anthrax treatment, the use of adjunctive therapies such as anthrax toxin antagonists is a consideration.
Bacillus anthracis; diagnosis; pathogenesis; treatment
In October 2001, two inhalational anthrax and four cutaneous anthrax cases, resulting from the processing of Bacillus anthracis–containing envelopes at a New Jersey mail facility, were identified. Subsequently, we initiated stimulated passive hospital-based and enhanced passive surveillance for anthrax-compatible syndromes. From October 24 to December 17, 2001, hospitals reported 240,160 visits and 7,109 intensive-care unit admissions in the surveillance area (population 6.7 million persons). Following a change to reporting criteria on November 8, the average of possible inhalational anthrax reports decreased 83% from 18 to 3 per day; the proportion of reports requiring follow-up increased from 37% (105/286) to 41% (47/116). Clinical follow-up was conducted on 214 of 464 possible inhalational anthrax patients and 98 possible cutaneous anthrax patients; 49 had additional laboratory testing. No additional cases were identified. To verify the limited scope of the outbreak, surveillance was essential, though labor-intensive. The flexibility of the system allowed interim evaluation, thus improving surveillance efficiency.
Bacillus anthracis; anthrax; surveillance; bioterrorism
Workers’ compensation insurance in some states may not provide coverage for medical evaluation costs of workplace exposures related to potential bioterrorism acts if there is no diagnosed illness or disease. Personal insurance also may not provide coverage for these exposures occurring at the workplace. Governmental entities, insurers, and employers need to consider how to address such situations and the associated costs. The objective of this study was to examine characteristics of workers and total costs associated with workers’ compensation claims alleging potential exposure to the bioterrorism organism B. anthracis.
We examined 192 claims referred for review to the Ohio Bureau of Workers’ Compensation (OBWC) from October 10, 2001, through December 20, 2004.
Although some cases came from out-of-state areas where B. anthracis exposure was known to exist, no Ohio claim was associated with true B. anthracis exposure or B. anthracis-related illness. Of the 155 eligible claims, 126 included medical costs averaging $219 and ranging from $24 to $3,126. There was no difference in mean cost for government and non-government employees (p=0.202 Wilcoxon).
The number of claims and associated medical costs for evaluation and treatment of potential workplace exposure to B. anthracis were relatively small. These results can be attributed to several factors, including no documented B. anthracis exposures and disease in Ohio and prompt transmission of recommended diagnostic and prophylactic treatment protocols to physicians. How employers, insurers, and jurisdictions address payment for evaluation and treatment of potential or documented exposures resulting from a potential terrorism-related event should be addressed proactively.
In 2001, a bioterrorism attack involving Bacillus anthracis spore-laced letters resulted in 22 cases of inhalation anthrax, with five fatalities. This incident identified gaps in our health care system and precipitated a renewed interest in identifying both therapeutics and rapid diagnostic assays. To address those gaps, well-characterized animal models that resemble the human disease are needed. In addition, a rapid assay for a reliable diagnostic marker is key to the success of these efforts. In this study, we exposed African green monkeys to B. anthracis spores; examined clinical signs and physiological parameters, including fever, heart rate, complete blood count, and bacteremia; and evaluated the PCR assay and electrochemiluminescence (ECL) immunoassay for the biomarkers protective antigen and capsule. The results demonstrated that although there were neither objective clinical nor physiological signs that consistently identified either infection or the onset of clinical anthrax disease, the African green monkey is a suitable animal model exhibiting a disease course similar to that observed in the rhesus model and humans. We also demonstrated that detection of the biomarkers protective antigen and capsule correlated with bacterial loads in the blood of these nonhuman primates. The ECL immunoassay described here is simple and sensitive enough to provide results in one to two hours, making this assay a viable option for use in the diagnosis of anthrax, leading to timely initiation of treatment, which is a key component of B. anthracis therapeutic development.
The biological attacks with powders containing Bacillus anthracis sent through the mail during September and October 2001 led to unprecedented public health and law enforcement investigations, which involved thousands of investigators from federal, state, and local agencies. Following recognition of the first cases of anthrax in Florida in early October 2001, investigators from Centers for Disease Control and Prevention (CDC) and the Federal Bureau of Investigation (FBI) were mobilized to assist investigators from state and local public health and law enforcement agencies. Although public health and criminal investigations have been conducted in concert in the past, the response to the anthrax attacks required close collaboration because of the immediate and ongoing threat to public safety. We describe the collaborations between CDC and FBI during the investigation of the 2001 anthrax attacks and highlight the challenges and successes of public health and law enforcement collaborations in general.
police power; anthrax; quarantine; bioterrorism response; Bacillus anthracis; law; criminal investigation; Federal Bureau of Investigation
The CDC recommend 60 days of oral antibiotics combined with a three-dose series of the anthrax vaccine for prophylaxis after potential exposure to aerosolized Bacillus anthracis spores. The anthrax vaccine is currently not licensed for anthrax postexposure prophylaxis and has to be made available under an Investigational New Drug protocol. Postexposure prophylaxis based on antibiotics can be problematic in cases where the use of antibiotics is contraindicated. Furthermore, there is a concern that an exposure could involve antibiotic-resistant strains of B. anthracis. Availability of alternate treatment modalities that are effective in prophylaxis of inhalation anthrax is therefore highly desirable. A major research focus toward this end has been on passive immunization using polyclonal and monoclonal antibodies against B. anthracis toxin components. Since 2001, significant progress has been made in isolation and commercial development of monoclonal and polyclonal antibodies that function as potent neutralizers of anthrax lethal toxin in both a prophylactic and therapeutic setting. Several new products have completed Phase I clinical trials and are slated for addition to the National Strategic Stockpile. These rapid advances were possible because of major funding made available by the US government through programs such as Bioshield and the Biomedical Advanced Research and Development Authority. Continued government funding is critical to support the development of a robust biodefense industry.
antibiotic treatment; biodefense funding; inhalation anthrax; lethal factor; medical countermeasures; prophylactic antibodies; protective antigen; vaccination
In July 1993, a liquid suspension of Bacillus anthracis was aerosolized from the roof of an eight-story building in Kameido, Tokyo, Japan, by the religious group Aum Shinrikyo. During 1999 to 2001, microbiologic tests were conducted on a liquid environmental sample originally collected during the 1993 incident. Nonencapsulated isolates of B. anthracis were cultured from the liquid. Multiple-locus, variable-number tandem repeat analysis found all isolates to be identical to a strain used in Japan to vaccinate animals against anthrax, which was consistent with the Aum Shinrikyo members’ testimony about the strain source. In 1999, a retrospective case-detection survey was conducted to identify potential human anthrax cases associated with the incident, but none were found. The use of an attenuated B. anthracis strain, low spore concentrations, ineffective dispersal, a clogged spray device, and inactivation of the spores by sunlight are all likely contributing factors to the lack of human cases.
Bacillus anthracis; bioterrorism; anthrax; epidemiology; Aum Shinrikyo; Japan
In 2001, envelopes loaded with Bacillus anthracis spores were mailed to Senators Daschle and Leahy as well as to the New York Post and NBC News buildings. Additional letters may have been mailed to other news agencies because there was confirmed anthrax infection of employees at these locations. These events heightened the awareness of the lack of understanding of the mechanism(s) by which objects contaminated with a biological agent might spread disease. This understanding is crucial for the estimation of the potential for exposure to ensure the appropriate response in the event of future attacks. In this study, equipment to simulate interactions between envelopes and procedures to analyze the spread of spores from a “payload” envelope (i.e., loaded internally with a powdered spore preparation) onto neighboring envelopes were developed. Another process to determine whether an aerosol could be generated by opening contaminated envelopes was developed. Subsequent generations of contaminated envelopes originating from a single payload envelope showed a consistent two-log decrease in the number of spores transferred from one generation to the next. Opening a tertiary contaminated envelope resulted in an aerosol containing 103 B. anthracis spores. We developed a procedure for sampling contaminated letters by a nondestructive method aimed at providing information useful for consequence management while preserving the integrity of objects contaminated during the incident and preserving evidence for law enforcement agencies.
After the human anthrax cases and exposures in 2001, the Illinois Department of Public Health received an increasing number of environmental and human samples (1,496 environmental submissions, all negative for Bacillus anthracis). These data demonstrate increased volume of submissions to a public health laboratory resulting from fear of bioterrorism.
anthrax; bioterrorism; Bacillus anthracis; dispatch
Anthrax is a disease of human beings and animals caused by the encapsulated, spore-forming, Bacillus anthracis. The potential role of insects in the spread of B. anthracis to humans and domestic animals during an anthrax outbreak has been confirmed by many studies. Among insect vectors, the house fly Musca domestica is considered a potential agent for disease transmission. In this study, laboratory-bred specimens of Musca domestica were infected by feeding on anthrax-infected rabbit carcass or anthrax contaminated blood, and the presence of anthrax spores in their spots (faeces and vomitus) was microbiologically monitored. It was also evaluated if the anthrax spores were able to germinate and replicate in the gut content of insects. These results confirmed the role of insects in spreading anthrax infection. This role, although not major, given the huge size of fly populations often associated with anthrax epidemics in domestic animals, cannot be neglected from an epidemiological point of view and suggest that fly control should be considered as part of anthrax control programs.
The October 2001 anthrax attacks heralded a new era of bioterrorism threat in the U.S. At the time, little systematic data on mental health effects were available to guide authorities' response. For this study, which was conducted 7 months after the anthrax attacks, structured diagnostic interviews were conducted with 137 Capitol Hill staff workers, including 56 who had been directly exposed to areas independently determined to have been contaminated. Postdisaster psychopathology was associated with exposure; of those with positive nasal swab tests, PTSD was diagnosed in 27% and any post-anthrax psychiatric disorder in 55%. Fewer than half of those who were prescribed antibiotics completed the entire course, and only one-fourth had flawless antibiotic adherence. Thirty percent of those not exposed believed they had been exposed; 18% of all study participants had symptoms they suspected were symptoms of anthrax infection, and most of them sought medical care. Extrapolation of raw numbers to large future disasters from proportions with incorrect belief in exposure in this limited study indicates a potential for important public health consequences, to the degree that people alter their healthcare behavior based on incorrect exposure beliefs. Incorrect belief in exposure was associated with being very upset, losing trust in health authorities, having concerns about mortality, taking antibiotics, and being male. Those who incorrectly believe they were exposed may warrant concern and potential interventions as well as those exposed. Treatment adherence and maintenance of trust for public health authorities may be areas of special concern, warranting further study to inform authorities in future disasters involving biological, chemical, and radiological agents.