What is Anthrax? Transmission, Symptoms, Vaccine

by CDC

What is anthrax?

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 inhalation 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 inhalation 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.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.