Fact Sheet: Anthrax (Bacillus Anthracis)

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 (sheep, cattle, goats and other herbivores). Until the middle of the 20th century when an effective veterinary vaccine was developed, and the subsequent advent of antibiotics, anthrax was one of the foremost causes of uncontrolled mortality in cattle, sheet, goats, horses and pigs worldwide.

How common is Anthrax and how is it spread?

Anthrax is most common in agricultural regions where it occurs in animals. Most areas of the world are still affected by anthrax including South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean and the Middle East. It is also still reported sporadically in North America. Humans usually contract Anthrax either directly or indirectly through contact with infected animals or their products. The anthrax bacteria can also live in the soil for many years. Humans may become infected with anthrax by inhaling contaminated soil particles or by handling hides, wool or hair from diseased animals. Infection in the intestinal tract can occur from eating undercooked meat from a diseased animal. Anthrax is a seasonal disease; incidence in any one place is usually related to temperature, rains or drought; however, the conditions that predispose to outbreaks differ from location to location. Climate probably acts directly or indirectly by influencing the way in which an animal comes into contact with the spores (for example, grazing closer to the soil in dry periods when grass is short or sparse, or movement of herds to restricted sites when water becomes scarce).

What are the forms of Anthrax and what are the symptoms?

Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal.

Cutaneous: About 95% of anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated animal products (wool, hides, leather or hair). 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. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.

Intestinal: 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.

How soon after infection do symptoms appear?

Incubation is usually seven days.

Can anthrax be spread from person-to-person?

Spreading infection from person-to-person is highly unlikely. So in visiting or managing a patient with inhalational anthrax, contagion should not be a concern.

How is anthrax diagnosed?

Anthrax is diagnosed by isolating the bacteria from the blood, skin lesions or respiratory secretions or by measuring specific antibodies in the blood of persons with suspected cases.

Does past infection with anthrax make a person immune?

A second infection with this disease is highly unlikely.

How many cases of anthrax in humans have been reported in the United States?

Human anthrax is a rare disease in the United States. Only about 18 cases of inhalation anthrax were reported from 1900 to 1978. Approximately 224 U.S. cases of skin infection were reported between 1944 and 1994. However, in Africa, the nation of Zimbabwe experienced a terrible epidemic of skin anthrax between 1979 and 1985, with more than 10,000 cases reported.

What is the treatment?

Doctors can prescribe effective antibiotics. To be effective, treatment should be initiated early. If left untreated, the disease can be fatal. Natural strains of anthrax may be resistant to many antibiotics, but most are sensitive to penicillin. Either of two antibiotics is recommended: doxycyline and ciprofloxacin. Because anthrax spores can remain hidden in the lungs for a long time, it is recommended that treatment continue for at least 60 days. It is also recommended that people NOT stockpile antibiotics. Treatment should not be started unless on the advice of a physician or public health authorities. These drugs can have serious side effects for some individuals.

Is there a way to prevent infection?

In countries where anthrax is common and vaccination levels of animal herds are low, humans should avoid contact with livestock and animal products and avoid eating meat that has not been properly slaughtered and thoroughly cooked. Also, an anthrax vaccine has been licensed for use in humans, and is reported to be 93% effective in protecting against anthrax. Self-dosing with antibiotics is not recommended. This could have enormous health consequences.

How can I tell the difference between the flu and an anthrax infection?

Early symptoms of inhalation anthrax are the same as those of a case of the flu. Treatment to prevent anthrax begins only after a person has had a suspected exposure. There is no quick test to show whether a person has been exposed to the anthrax bacteria. If a cold or flu seems to suddenly become worse, seek immediate medical attention.

What is the anthrax vaccine?

The anthrax vaccine is manufactured and distributed by BioPort Corporation, Lansing, Michigan. The vaccine is a cell-free filtrate vaccine, which means it contains no ded or live bacteria in the preparation. The final product contains no more than 2.4 mg of aluminum hydroxide as adjuvant. Anthrax vaccines intended for animals should not be used in humans.

Who should get vaccinated?

The Advisory Committee on Immunization Practices has recommend 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. (Incidence is low in the United States, but 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 (as when it is used as a biological warfare weapon). The anthrax Vaccine Immunization Program in the U.S. Army Surgeon General’s Office can be reached at 1-877-GETVACC (1-877-438-8222). http://www.anthrax.osd.mil
  • Pregnant women should be vaccinated only if absolutely necessary.

Are there adverse reactions to the vaccine?

Mild local reactions occur in 30% of recipients and consist of slight tenderness and redness at the injection site. Severe local reactions are infrequent and consist of extensive swelling of the forearm in addition to the local reaction. Systemic reactions occur in fewer than 0.2% of recipients.

What should I do if I think I’ve received a package or letter containing anthrax?

Most importantly, don’t panic. If you think the letter or package contained anthrax or any other infectious agent, here are some steps to take:

  • Don’t shake or empty the package or envelope. Do not try to clean up any spilled powder or fluid.
  • Put the envelope or package into a plastic bag or other container to prevent the contents from leaking out. If you are unable to locate a container, cover the envelope or package with clothing, paper or a trash can and DO NOT remove the cover.
  • Get everyone out of the room and close the door. Keep others from entering the room.
  • Immediately wash your hands with soap and warm water.
  • Call the local police and report the incident. If you are at work, calling the local building security officer and/or your supervisor.
  • Make a list of all individuals who were in the room when you opened the package. Give the list to the local police and public health authorities.
  • Remove all contaminated clothing and put it into a plastic bag that can be sealed. Give the bag of contaminated clothing to the police as soon as possible.
  • Shower with soap and water as soon as possible. DO NOT use bleach or disinfectant.
  • DO NOT start taking antibiotics unless advised to do so by your physician or the local public health authorities