Cutaneous anthrax

Definition

Cutaneous anthrax is an infection of the skin due to direct contact with the bacteria Bacillus anthracis.

Alternative Names

Anthrax - skin

Causes, incidence, and risk factors

Anthrax is caused by the bacteria Bacillus anthracis. While anthrax commonly affects hoofed animals such as sheep and goats, humans may get sick from anthrax, too. The most common type of anthrax infection in people is cutaneous anthrax, an infection of the skin.

The main risk factor for getting cutaneous anthrax is contact with animal hides or hair, bone products, and wool, as well as contact with infected animals. Therefore, those most at risk for anthrax include farm workers, veterinarians, and tannery and wool workers.

Cutaneous anthrax occurs after the bacteria touch a cut or scrape on the skin.

Anthrax is a potential agent for use as a biological weapon or for bioterrorism. In 2001, bioterrorist activities involving the United States Postal Service infected 22 people with anthrax. Seven survivors had confirmed cases of cutaneous anthrax. Most bioterrorism experts have concluded that it is technologically difficult to use anthrax effectively as a weapon on a large scale.

Symptoms

Between 1 and 12 days after exposure, an itchy sore develops, similar to an insect bite. This sore may blister and form a black ulcer (sore), which is usually painless. It is usually surrounded by significant swelling. A scab often develops, and then dries and falls off within 2 weeks, although complete healing can take longer.

Some patients also have painful lymph nodes, fever, headache, and a general ill-feeling (malaise).

Signs and tests

A culture of the skin lesions should be done to identify the bacteria that cause anthrax.

Treatment

Cutaneous anthrax is treated with antibiotics, most often doxycycline or ciprofloxacin. Ciprofloxacin has been the antibiotic of choice during a suspected anthrax outbreak.

Because anthrax spores may take up to 60 days to grow, the length of treatment is usually 60 days.

Expectations (prognosis)

The outlook is excellent when anthrax is treated. Death is extremely rare when antibiotics are promptly given.

Complications

In some cases, the infection can spread through the bloodstream, leading to shock and death.

Calling your health care provider

Call your health care provider if you know you have been exposed to anthrax, or if you develop a skin lesion as described above.

Prevention

For individuals who have been truly exposed to anthrax (but have no signs and symptoms of the disease), preventive antibiotics such as ciprofloxacin, penicillin, or doxycycline may be offered, depending on the particular strain of anthrax.

Cutaneous anthrax is not known to spread from person to person. Household contacts of individuals with cutaneous anthrax do not need antibiotics unless they have also been exposed to the same source of anthrax.

An anthrax vaccine is available to selected military personnel, but not to the general public.

References

Inglesby TV, O'Toole T, Henderson DA, et al. Anthrax as a Biological Weapon, 2002. JAMA. 2002;287:2236-2252.

Lucey DR. Anthrax. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 317.

Reissman DB, Whitney EA, Taylor TH Jr, et al. One-Year Health Assessment of Adult Survivors of Bacillus anthracis Infection. JAMA. 2004;291:1994-1998.