Anthrax is an acute infectious disease caused by the spore-forming bacterium
Bacillus anthracis. Anthrax most commonly occurs in wild and domestic lower
vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but
it can also occur in humans when they are exposed to infected animals or to
tissue from infected animals or when anthrax spores are used as a bioterrorist
weapon.
Transmission
How is anthrax transmitted?
Anthrax is not known to spread from one person to another person. B.
anthracis spores can live in the soil for many years, and humans can become
infected with anthrax by handling products from infected animals or by inhaling
anthrax spores from contaminated animal products. Anthrax can also be spread by
eating undercooked meat from infected animals. It is rare to find infected
animals in the United States. Anthrax spores can be used as a bioterrorist
weapon, as was the case in 2001, when Bacillus anthracis spores had been
intentionally distributed through the postal system, causing 22 cases of
anthrax, including 5 deaths.
What are the types of anthrax infection?
Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and
gastrointestinal.
Cutaneous:
Most (about 95%) anthrax infections occur when the
bacterium enters a cut or abrasion on the skin, such as when handling
contaminated wool, hides, leather or hair products (especially goat hair) of
infected animals. Skin infection begins as a raised itchy bump that resembles
an insect bite but within 1-2 days develops into a vesicle and then a painless
ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic
(dying) area in the center. Lymph glands in the adjacent area may swell. About
20% of untreated cases of cutaneous anthrax will result in death. Deaths are
rare with appropriate antimicrobial therapy.
Inhalation:
Initial symptoms may resemble a common cold – sore throat,
mild fever, muscle aches and malaise. After several days, the symptoms may
progress to severe breathing problems and shock. Inhalation anthrax is usually
fatal.
Gastrointestinal:
The intestinal disease form of anthrax may follow
the consumption of contaminated meat and is characterized by an acute
inflammation of the intestinal tract. Initial signs of nausea, loss of
appetite, vomiting, fever are followed by abdominal pain, vomiting of blood,
and severe diarrhea. Intestinal anthrax results in death in 25% to 60% of
cases.
What are the case fatality rates for the various forms of anthrax?
Early treatment of cutaneous anthrax is usually curative, and early treatment
of all forms is important for recovery. Patients with cutaneous anthrax have
reported case fatality rates of 20% without antibiotic treatment and less than
1% with it. Although case-fatality estimates for inhalational anthrax are based
on incomplete information, the rate is extremely high, approximately 75%, even
with all possible supportive care including appropriate antibiotics. Estimates
of the impact of the delay in postexposure prophylaxis or treatment on survival
are not known. For gastrointestinal anthrax, the case-fatality rate is estimated
to be 25%-60% and the effect of early antibiotic treatment on that case-fatality
rate is not defined.
Symptoms
What are the symptoms for anthrax?
These symptoms can occur within 7 days of infection:
Fever (temperature greater than 100 degrees F). The fever may be
accompanied by chills or night sweats.
Flu-like symptoms.
Cough, usually a non-productive cough, chest discomfort, shortness of
breath, fatigue, muscle aches
Sore throat, followed by difficulty swallowing, enlarged lymph nodes,
headache, nausea, loss of appetite, abdominal distress, vomiting, or diarrhea
A sore, especially on your face, arms or hands, that starts as a raised
bump and develops into a painless ulcer with a black area in the center.
How can I know my cold or flu is not anthrax?
Many human illnesses begin with what are commonly referred to as "flu-like"
symptoms, such as fever and muscle aches. However, in most cases anthrax can be
distinguished from the flu because the flu has additional symptoms. In previous
reports of anthrax cases, early symptoms usually did not include a runny nose,
which is typical of the flu and common cold.
Preventive/Vaccine
Which antibiotics does CDC recommend for prevention of inhalational anthrax?
In selecting an antibiotic, we will be guided by the organism's culture and
sensitivity results, history of allergic reactions, age and health status
factors and antibiotic availability. 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, or levofloxacin for adults.
If an anthrax event occurs, should people buy and store antibiotics?
There is no need to buy or store antibiotics, and indeed, it can be
detrimental to both the individual and to the community. First, only people who
are exposed to anthrax should take antibiotics, and health authorities must make
that determination. Second, individuals may not stockpile or store the correct
antibiotics. Third, under emergency plans, the federal government can ship
appropriate antibiotics from its stockpile to wherever they are needed.
What drugs are FDA-approved for treatment of anthrax?
Ciprofloxacin, doxycycline and penicillin are FDA-approved for the treatment
of anthrax in adults and children.
Is there a vaccination for anthrax?
A protective vaccine has been developed for anthrax; however, it is primarily
given to military personnel. Vaccination is recommended only for those at high
risk, such as workers in research laboratories that handle anthrax bacteria
routinely. The antibiotics used in post exposure prophylaxis are very effective
in preventing anthrax disease from occurring after an exposure.
Is the anthrax vaccine available to the public?
A vaccine has been developed for anthrax that is protective against invasive
disease, but it is currently only recommended for high-risk populations. CDC and
academic partners are continuing to support the development of the next
generation of anthrax vaccines.
Who should be vaccinated against anthrax?
The Advisory Committee on Immunization Practices (ACIP) has recommended
anthrax vaccination for the following groups:
Persons who work directly with the organism in the laboratory.
Persons who work with imported animal hides or furs in areas where
standards are insufficient to prevent exposure to anthrax spores.
Persons who handle potentially infected animal products in high-incidence
areas; while incidence is low in the United States, veterinarians who travel
to work in other countries where incidence is higher should consider being
vaccinated.
Military personnel deployed to areas with high risk for exposure to the
organism.
.
Testing
Can I get screened or tested to find out whether I have been exposed to
anthrax?
There is no screening test for anthrax; there is no test that a doctor can do
for you that says you've been exposed to or carry it. The only way exposure can
be determined is through a public health investigation. Nasal swabs and
environmental tests, are not tests to determine whether an individual should be
treated. These kinds of tests are used only to determine the extent of exposure
in a given building or workplace.
What is a nasal swab test?
A nasal swab involves placing a swab inside the nostrils and taking a
culture. The CDC and the U.S. Department of Health and Human Services do not
recommend the use of nasal swab testing by clinicians to determine whether a
person has been exposed to Bacillus anthracis, the bacteria responsible for
anthrax, or as a means of diagnosing anthrax. At best, a positive result may be
interpreted only to indicate exposure; a negative result does not exclude the
possibility of exposure. Also, the presence of spores in the nose does not mean
that the person has inhalational anthrax. The nose naturally filters out many
things that a person breathes, including bacterial spores. To have inhalational
anthrax, a person must have the bacteria deep in the lungs, and also have
symptoms of the disease.
Another reason not to use nasal swabs is that most hospital laboratories
cannot fully identify anthrax spores from nasal swabs. They are able to tell
only that bacteria that resemble anthrax bacteria are present.
If patients are suspected of being exposed to anthrax, should they be
quarantined or should other family members be tested?
Anthrax is not known to spread from one person to another person. Therefore,
there is no need to quarantine individuals suspected of being exposed to anthrax
or to immunize or treat contacts of persons ill with anthrax, such as household
contacts, friends, or coworkers, unless they also were also exposed to the same
source of infection.
Treatment
What is the treatment for patients with inhalational and cutaneous anthrax?
CDC made treatment recommendations for cases of inhalational and cutaneous
anthrax associated with the bioterrorism attack of 2001. These recommendations
can be found in the MMWR, 10/26/2001; 50(42), 909-919.
What drugs are FDA-approved for treatment of anthrax?
Ciprofloxacin, doxycycline and penicillin are FDA-approved for the treatment
of anthrax in adults and children.
Safety Issues/Mail
How can mail get cross-contaminated with anthrax?
CDC does not have specific studies to address this, however,
cross-contamination of the mail could occur during the processing, sorting, and
delivery of mail when an envelope comes in contact with an envelope, piece of
equipment (e.g., an electronic sorting machine), or other surface that is
contaminated with Bacillus anthracis spores. In addition, airborne spores in
contaminated postal facilities before they were cleaned might play a role.
When there is a known incident, how can I prevent anthrax exposure from
cross-contaminated mail?
There are no scientifically proven recommendations for preventing exposure.
However, there are some common-sense steps people can take:
Do not open suspicious mail
Keep mail away from your face when you open it
Do not blow or sniff mail or mail contents
Avoid vigorous handling of mail, such as tearing or shredding
Wash your hands after handling the mail
Discard envelopes after opening mail.
What should people do when they get a letter or package with powder?
Handling of Suspicious Packages or Envelopes*
Do not shake or empty the contents of any suspicious package or envelope.
Do not carry the package or envelope, show it to others or allow others to
examine it.
Put the package or envelope down on a stable surface; do not sniff, touch,
taste, or look closely at it or at any contents which may have spilled.
Alert others in the area about the suspicious package or envelope. Leave
the area, close any doors, and take actions to prevent others from entering
the area. If possible, shut off the ventilation system.
WASH hands with soap and water to prevent spreading potentially infectious
material to face or skin. Seek additional instructions for exposed or
potentially exposed persons.
If at work, notify a supervisor, a security officer, or a law enforcement
official. If at home, contact the local law enforcement agency.
If possible, create a list of persons who were in the room or area when
this suspicious letter or package was recognized and a list of persons who
also may have handled this package or letter. Give this list to both the local
public health authorities and law enforcement officials.
*These recommendations were published on October 26, 2001, in "Update:
Investigation of bioterrorism-related anthrax and interim guidelines for
exposure management and antimicrobial therapy" MMWR 2001; 50(42):909-919.
What is the risk for getting anthrax from handling my own mail?
If there is a risk for inhalational anthrax associated with exposure to
cross-contaminated mail, it is very low. For example, about 85 million pieces of
mail were processed on the few days in 2001 after envelopes containing Bacillus
anthracis (addressed to two U.S. senators) passed through the New Jersey and
District of Columbia sorting facilities until they were closed. Despite the fact
that both of these facilities had evidence of widespread environmental
contamination with B. anthracis spores and the fact that public health officials
had been aggressively looking for anthrax cases, no new cases of anthrax were
identified during that time.
When the possibility of cross-contamination of the mail exists, should I take
antibiotics?
Preventive antibiotics are not recommended for persons who routinely open or
handle mail, either at home or at the workplace. Antimicrobial prophylaxis is
recommended only in certain specific situations such as for persons exposed to
an air space known to be contaminated with aerosolized Bacillus anthracis or for
persons in a postal sorting facility in which an envelope containing B.
anthracis spores was processed. CDC's complete recommendations on antimicrobial
prophylaxis are contained in the November 9, 2001 MMWR. Additional
recommendations for use of vaccine as part of post-exposure prophylaxis are
contained in the November 15, 2002 MMWR 51(45):1024-1026
.
What kinds of anthrax worker safety guidelines have been issued?
The recommendations are divided into four categories. They are engineering
controls, administrative controls, housekeeping controls, and personal
protective equipment for workers. The guidelines describe measures that should
be implemented in mail-handling/processing sites to prevent potential exposures
to B. anthracis spores.