October 19, 2001 / 50(41);889-893
Update: Investigation of Anthrax Associated with Intentional Exposure and
Interim Public Health Guidelines, October 2001
On October 4, 2001, CDC and state and local public health authorities
reported a case of inhalational anthrax in Florida (1).
Additional cases of anthrax subsequently have been reported from Florida and New
York City. This report updates the findings of these case investigations, which
indicate that infections were caused by the intentional release of Bacillus
anthracis. This report also includes interim guidelines for postexposure
prophylaxis for prevention of inhalational anthrax and other information to
assist epidemiologists, clinicians, and laboratorians responding to intentional
For these investigations, a confirmed case of anthrax was defined as 1) a
clinically compatible case of cutaneous, inhalational, or gastrointestinal
illness* that is laboratory confirmed by isolation of B. anthracis from
an affected tissue or site or 2) other laboratory evidence of B. anthracis
infection based on at least two supportive laboratory tests. A suspected case
was defined as 1) a clinically compatible case of illness without isolation of
B. anthracis and no alternative diagnosis, but with laboratory evidence
of B. anthracis by one supportive laboratory test or 2) a clinically
compatible case of anthrax epidemiologically linked to a confirmed environmental
exposure, but without corroborative laboratory evidence of B. anthracis
Laboratory criteria for diagnosis of anthrax consist of 1) isolation and
confirmation of B. anthracis from a clinical specimen collected from an
affected tissue or site or 2) other supportive laboratory tests, including (a)
evidence of B. anthracis DNA by polymerase chain reaction (PCR) from
specimens collected from an affected tissue or site, (b) demonstration of B.
anthracis in a clinical specimen by immunohistochemical staining, or (c)
other laboratory tests (e.g., serology) that may become validated by laboratory
On October 2, the Palm Beach County Health Department (PBCHD) and the Florida
Department of Health (FDOH) were notified of a possible anthrax case in Palm
Beach County. The suspected case was identified when a gram stain of
cerebrospinal fluid (CSF) revealed a gram-positive bacilli. An epidemiologic
investigation was initiated by FDOH, PBCHD, and the FDOH state laboratory. The
state laboratory and CDC confirmed B. anthracis from a culture of CSF on
October 4. Later the same day, FDOH and CDC epidemiologists and laboratory
workers arrived in Palm Beach County to assist PBCHD with the investigation. As
of October 16, two confirmed cases of inhalational anthrax have been identified.
The index patient was a 63-year-old male resident of Palm Beach County who
sought medical care at a local hospital on October 2 with fever and altered
mental status. Despite antibiotic therapy, his clinical condition deteriorated
rapidly, and he died on October 5. An autopsy performed on October 6 confirmed
the cause of death as inhalational anthrax. An investigation revealed no obvious
exposures to B. anthracis.
On October 1, the second patient, a 73-year-old co-worker of the index
patient, was admitted to a local hospital for pneumonia. On October 5, a nasal
swab was obtained from the patient that yielded a positive culture for B.
anthracis. Subsequent testing revealed positive PCR tests for B.
anthracis in hemorrhagic pleural fluid and reactive serologic tests. The
patient remains hospitalized on antibiotic therapy. Enhanced case finding and
retrospective and prospective surveillance systems were initiated in Palm Beach,
and surrounding counties. Environmental assessments and sampling were performed
at the index patient's home, work site, and travel destinations for the 60 days
preceding symptom onset. Environmental sampling revealed B. anthracis
contamination of the work site, specifically implicating mail or package
delivery. Environmental samples of other locations the patient visited,
including extensive sampling of his home, were negative.
Questionnaires were administered to employees at the index patient's work
site. Postexposure prophylaxis was administered, and nasal swabs were obtained
from those with exposure to the work site for >1 hour since August 1. Of 1,075
nasal swabs performed, one was positive for B. anthracis. Environmental
and co-worker testing indicated contamination of specific locations at the work
site. The investigation and environmental sampling are ongoing.
On October 9, the New York City Department of Health notified CDC of a person
with a skin lesion consistent with cutaneous anthrax. CDC sent a team to New
York City to provide epidemiologic and laboratory support to local health
officials. As of October 16, two persons with confirmed cases of cutaneous
anthrax have been identified. One person with confirmed anthrax was a
38-year-old woman who had handled a suspicious letter postmarked September 18 at
her workplace. The letter contained a powder that subsequently was confirmed to
contain B. anthracis. On September 25, the patient had a raised lesion on
the chest, which over the next 3 days developed surrounding erythema and edema.
By September 29, the patient developed malaise and headache. On October 1, a
clinician examined the patient and described an approximately 5 cm long
oval-shaped lesion with a raised border, small satellite vesicles, and profound
edema. The lesion was nonpainful and was associated with left cervical
lymphadenopathy. Serous fluid from the lesion was obtained and was negative by
gram stain and culture. The patient was prescribed oral ciprofloxacin. Over the
next several days, the lesion developed a black eschar, and a biopsy was
obtained and sent to CDC for testing. The tissue was positive by
immunohistochemical staining for the cell wall antigen of B. anthracis.
The other person with confirmed cutaneous anthrax was a 7-month-old infant
who visited his mother's workplace on September 28. The next day, the infant had
an apparently nontender, massively edematous, weeping skin lesion on his left
arm; he was treated with intravenous antibiotics. Over the next several days,
the lesion became ulcerative and developed a black eschar; clinicians
presumptively attributed the lesion to a spider bite. The infant's clinical
course was complicated by hemolytic anemia and thrombocytopenia, requiring
intensive care. The diagnosis of cutaneous anthrax was first considered on
October 12 after the announcement of the other confirmed anthrax case in New
York City. A serum specimen collected on October 2 was positive for B.
anthracis by PCR testing at CDC; a skin biopsy obtained on October 13 was
positive by immunohistochemical staining at CDC for the cell wall antigen of
B. anthracis. No suspicious letter with powder was identified at the
mother's workplace. Both patients were treated with ciprofloxacin and are
B. anthracis grew from swabs (two nasal and one facial skin swab) from
three other persons, suggesting exposure to anthrax. One of the exposures was in
a law enforcement officer who brought the letter containing B. anthracis
from the index patient's workplace to the receiving laboratory. The other two
exposures were in technicians who had processed the letter in the laboratory.
Environmental sampling in both workplaces is ongoing and investigations of other
exposed persons continue.
Reported by: L Bush, MD, Atlantis; J Malecki, MD, Palm Beach County Health
Dept, Palm Beach; S Wiersma, MD, State Epidemiologist, Florida Dept of Health. K
Cahill, MD, R Fried, MD; M Grossman, MD, Columbia Presbyterian Medical Center; W
Borkowsky, MD, New York Univ Medical Center, New York, New York; New York City
Dept of Health. National Center for Infectious Diseases; and EIS officers, CDC.
The findings in this report indicate that four confirmed cases of anthrax
have resulted from intentional delivery of B. anthracis spores through
mailed letters or packages. These are the first confirmed cases of anthrax
associated with intentional exposure in the United States and represent a new
public health threat.
Anthrax is an acute infectious disease caused by the spore-forming bacterium
B. anthracis. It occurs most frequently as an epizootic or enzootic
disease of herbivores (e.g., cattle, goats, or sheep) that acquire spores from
direct contact with contaminated soil. Humans usually become infected through
direct contact with B. anthracis spores from infected animals or their
products (e.g., goat hair), resulting in cutaneous anthrax (2)
(Box 1). Inhalational and gastrointestinal are other forms
of the disease in the natural setting (4,5). Human-to-human transmission
has not been documented.
Clinical laboratorians should be alert to the presence of Bacillus
species in patient specimens. In particular, laboratorians should suspect B.
anthracis when the specimen is from a previously healthy patient with a
rapidly progressive respiratory illness or a cutaneous ulcer. If B. anthracis
is suspected, laboratories should immediately notify the health-care provider
and local and state public health staff. For rapid identification of B.
anthracis, state and local health departments should access the Laboratory
Response Network for Bioterrorism (LRN). LRN links state and local public health
laboratories with advanced capacity laboratories---including clinical, military,
veterinary, agricultural, water, and food-testing laboratories. Laboratorians
should contact their state public health laboratory to identify their local LRN
Postexposure prophylaxis is indicated to prevent inhalational anthrax after a
confirmed or suspected aerosol exposure. When no information is available about
the antimicrobial susceptibility of the implicated strain of B. anthracis,
initial therapy with ciprofloxacin or doxycycline is recommended for adults and
children (Table 1). Use of tetracyclines and
fluoroquinolones in children has adverse effects. The risks for these adverse
effects must be weighed carefully against the risk for developing
life-threatening disease. As soon as penicillin susceptibility of the organism
has been confirmed, prophylactic therapy for children should be changed to oral
amoxicillin 80 mg/kg of body mass per day divided every 8 hours (not to exceed
500 mg three times daily). B. anthracis is not susceptible to
cephalosporins or to trimethoprim/sulfamethoxazole, and these agents should not
be used for prophylaxis.
CDC is assisting other states and local areas in assessing anthrax exposures.
Additional information about anthrax and the public health response is available
at <http://www.bt.cdc.gov>. This information
was current as of 4 p.m., eastern daylight time, October 17, 2001.
Ongoing investigation of anthrax---Florida, October 2001. MMWR 2001;50:877.
- CDC. Human
anthrax associated with an epizootic among livestock---North Dakota, 2000.
DA, Rotz LD, Perkins BA. Use of anthrax vaccine in the United States:
recommendations of the Advisory Committee on Immunization Practice (ACIP).
MMWR 2000;49(no. RR-15).
- Brachman PS. Inhalational anthrax. Ann NY Acad Sci 1980;353:83--93.
- Brachman PS, Kaufmann A. Anthrax. In: Evans AS, Brachman PS, eds.
Bacterial infections of humans. New York, New York: Plenum Medical Book
* Cutaneous illness is characterized by a skin lesion
evolving from a papule, through a vesicular stage, to a depressed black eschar;
edema, erythema, or necrosis without ulceration may be present. Inhalational
illness is characterized by a brief prodrome resembling a "nonspecific febrile"
illness that rapidly progresses to a fulminant illness with signs of sepsis
and/or respiratory failure, often with radiographic evidence of mediastinal
widening; signs of bacterial meningitis may be present. Gastrointestinal
illness is characterized by severe abdominal pain usually accompanied by bloody
vomiting or diarrhea followed by fever and signs of septicemia.
BOX 1. Clinical forms of anthrax
Clinical Forms of Anthrax
The following clinical descriptions of anthrax are based on experience in
adults. The clinical presentation of anthrax in infants is not well defined.
Inhalational. Inhalational anthrax begins with a brief prodrome
resembling a viral respiratory illness followed by development of hypoxia and
dyspnea, with radiographic evidence of mediastinal widening. Inhalational
anthrax is the most lethal form of anthrax and results from inspiration of
8,000--50,000 spores of Bacillus anthracis (3).
The incubation period of inhalational anthrax among humans typically ranges from
1--7 days but may be possibly up to 60 days. Host factors, dose of exposure, and
chemoprophylaxis may affect the duration of the incubation period. Initial
symptoms include mild fever, muscle aches, and malaise and may progress to
respiratory failure and shock; meningitis frequently develops. Case-fatality
estimates for inhalational anthrax are extremely high, even with all possible
supportive care including appropriate antibiotics.
Cutaneous. Cutaneous anthrax is characterized by a skin lesion
evolving from a papule, through a vesicular stage, to a depressed black eschar.
The incubation period ranges from 1--12 days. The lesion is usually painless,
but patients also may have fever, malaise, headache, and regional
lymphadenopathy. The case fatality rate for cutaneous anthrax is 20% without,
and <1% with, antibiotic treatment.
Gastrointestinal. Gastrointestinal anthrax is characterized by severe
abdominal pain followed by fever and signs of septicemia. This form of anthrax
usually follows after eating raw or undercooked contaminated meat and can have
an incubation period of 1--7 days. An oropharyngeal and an abdominal form of the
disease have been described. Involvement of the pharynx is usually characterized
by lesions at the base of the tongue, dysphagia, fever, and regional
lymphadenopathy. Lower bowel inflammation typically causes nausea, loss of
appetite, and fever followed by abdominal pain, hematemesis, and bloody
diarrhea. The case-fatality rate is estimated to be 25%--60%. The effect of
early antibiotic treatment on the case-fatality rate is not established.
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