|
Overview
of Recent Broadcast by CDC, AHA, AMA and
Public Health Training Network re.
Anthrax
(State
labs are pushed to the limit and
hospital-based laboratorians may soon be
called upon to detect anthrax.)
By
Daniella Ki
"I
have a request," Secretary of the
U.S. Department of Health and Human
Services Tommy Thompson told an audience
of clinical professionals recently.
"At the present time, we've had
6,000 inquiries that have come into our
State Department
regarding anthrax exposure. Our
state laboratories are overrun by
requests and analyses so that they are
overwhelmed. I am hoping clinical
professionals can assist us in trying to
reduce this number of requests and also
be able to help out the
laboratories."
Thompson,
speaking at a recent informational
broadcast sponsored by the Centers for
Disease Control and Prevention, American
Hospital Association, American Medical
Association and Public Health Training
Network, was one of a group of experts
who presented clinical guidelines and
procedures for the early recognition,
diagnosis, treatment and reporting of
anthrax exposure. During the broadcast,
"Anthrax: What Every Clinician
Should Know," Thompson's words,
along with the other panelists, seemed
to reiterate what laboratorians were
already beginning to suspect. As fear
and panic coupled
with real threats of anthrax
exposure continue to make daily
headlines, diagnostic testing for the
infection will soon be too much for
government and state laboratories to
contend with and clinical environments
may be asked to lend a hand. Key to
offering invaluable help to the already
inundated state and government labs will
be clinical professionals with a solid
grasp of what the infection is, how to
properly diagnose it and how to report a
potential outbreak to authorities.
Understanding
Anthrax
Anthrax
is an acute infectious disease caused by
the spore-forming bacterium Bacillus
anthracis.
Before terrorist attacks using
the potentially lethal bacteria, anthrax
was most commonly found in mammals such
as cattle, sheep and goats, but was also
detected in humans who had been exposed
to infected animals.
Anthrax
infection occurs in three forms:
cutaneous, inhalation and
astrointestinal. Symptoms vary depending
on how the disease was contracted but
usually occur within seven days of
exposure.
The symptoms of cutaneous anthrax
usually include a raised itchy bump,
often misdiagnosed as a spider or insect
bite. The area then turns into a
painless ulcer with a black center.
Approximately 20 percent of untreated
cases result in death.
Conversely,
inhalation anthrax is usually fatal.
Symptoms resemble a common cold but then
lead to severe breathing problems and
shock after several days.
Gastrointestinal
anthrax usually follows consumption of
contaminated meat and is characterized
by an acute inflammation of the
intestinal tract. Symptoms include
nausea, loss of appetite, vomiting,
fever, abdominal pain, vomiting blood
(with blood) and severe diarrhea. About
25 percent to 60 percent of cases are
fatal.
- Testing
Until
now, anthrax infection was extremely
rare, and even now in the wake of
terrorist scares, the number of people
affected by the bacteria is still very
low. However,
in the case of an unfortunate
epidemic, laboratorians must be
prepared. According to the panelists,
upon suspecting anthrax, laboratorians
must immediately notify the local or
state health department and local or
state health laboratory.
According
to David Stephens, MD, a member of the
Meningitis and Special Pathogens
division of CDC and professor of
Medicine, director of the Division of
Infectious Diseases, Emory University
School of Medicine, the diagnosis of
cutaneous anthrax is done through blood
culture and biopsy. Polymerase chain
reaction (PCR) is also available, as is
immunofluorescence and
immunohistochemistry, which were the
methods used in the diagnosis of the
current cases.
Rapid
diagnostic tests for anthrax such as
enzyme-linked immunosorbent assay for
protective antigen and PCR are available
at reference laboratories. Given the
limited availability of these tests and
the time required to dispatch specimens
and perform assays, rapid diagnostic
testing would be primarily for
confirmation of diagnosis and
determining in vitro susceptibility to
antibiotics. In addition, these tests
will be used in the investigation and
management of anthrax hoaxes.
Microbiological
studies are a potential means to an
identification of outbreak. The most
useful microbiologic test is the
standard blood culture, which should be
grown in six to 24 hours. If the lab has
been alerted to the possibility of
anthrax, a review of colonial morphology
should provide a preliminary diagnosis
12 to 24 hours later. If cutaneous
anthrax is suspected, a Gram stain and
culture of vesicular fluid will confirm
the diagnosis.
Though
the nation has been put on high alert
for the bacteria, panelists reminded
clinical professionals that they are at
the frontline of public health and must
remain in control.
" I think it is very
important that we do not panic. We must
remain vigilant," said Dr.
Stephens.
"Individuals must be exposed
to B. anthracis spores to develop
anthrax. To cause disease, spores must
enter the skin, they must be swallowed
or inhaled. The disease can be prevented
after exposure to anthrax spores by
early treatment with appropriate
antibiotics. Lastly, anthrax is not
spread from person to person."
"
I keep thinking back to my medical
training, where the old line was if you
hear hoof beats, think horses, not
zebras. Unfortunately, what we need to
do now is still think horses, but in the
back of your mind think there could be a
zebra in this pack," said Jeffrey
Koplan, MD, MPH, director, CDC, and
moderator of the web cast. "Think
about whether or not there is anything
unusual about this case that doesn't fit
in with other ones. Have I seen a few
similar patterns that don't fit the
bill? Should there be extra laboratory
tests as unlikely as it might be-blood
test, culture, a patient that doesn't
seem to be getting better on
antibiotics? It's that vigilance that
caused an infectious disease specialist
in Palm Beach County to say, 'something
doesn't fit in this patient, I'm going
to ask for an anthrax culture.'
Remaining
calm but alert is the way we will deal
with any potential anthrax
outbreaks."
A free video tape of this Web
cast is available by calling
1-877-252-1200.
- Reference
-
- Inglesby,
T, Henderson, D, Bartlett, J, et al
Anthrax as a Biological Weapon. JAMA
1999;281(18):1735-1745.
|
|
