Anthrax, a once obscure disease, is a household name now. While the media hype has calmed down, the disease is still high on the CDC's list of possible bioterrorism agents. There are 3 types of anthrax - inhalational, gastrointestinal, and cutaneous. The inhalational form is the most talked about and the most deadly, but did you know there were 7 confirmed cases of cutaneous anthrax in 2001? One case occurred in a 7-month-old infant who was exposed to anthrax spores from the mother's workplace. What is cutaneous anthrax and is it as deadly as the inhalational form?
A Disease of Animals
Anthrax is actually a zoonotic disease, meaning it affects mainly animals, not humans. The animals affected are herbivores such as sheep, cattle, horses, and goats. Prior to September 11, humans were infected by handling contaminated animal products such as hides, hair, blood, and excrement from infected animals.
The bacteria that causes anthrax is Bacillus anthracis, a gram-positive, encapsulated, spore-forming bacteria. Cutaneous anthrax occurs when either the spores or the bacteria enter the body through a cut or abrasion. In most cases, symptoms begin to develop within 48 hours, although a range of 2-7 days has been seen.
Cutaneous anthrax begins as a small, red, itchy bump or papule at the site of infection. Within about 2 days, the bump develops into a fluid-filled blister that eventually ruptures. The lesion dries into a coal-black scab that covers an area of dead skin, hence the name anthrax (Greek for "coal").
Cutaneous Anthrax Pictures
These pictures show the progression of the disease:
If untreated, cutaneous anthrax is fatal in 20% of cases due to spread of the bacteria throughout the body and the release of deadly toxins in the bloodstream. However, with appropriate treatment, cutaneous anthrax is deadly in only 1% of cases. Even with proper treatment, the area of dead skin may continue to evolve.
Cutaneous anthrax, like the more deadly inhalational anthrax, is treated with antibiotics. The CDC recommends first-line treatment with ciprofloxacin or doxycycline. Other recommended antibiotics are erythromycin and penicillin. At this point the best course of action is to treat with ciprofloxacin and obtain bacterial cultures to test for specific antibiotic sensitivities. These results, usually available after 72 hours, can direct further antibiotic therapy. Cases of naturally occurring cutaneous anthrax are treated with a 10-14 day course of antibiotics. However, a full 60-day course of antibiotics is recommended for cases of cutaneous anthrax associated with bioterrorism.
The Food and Drug Administration (FDA) licensed a vaccine in 1970 for workers at high risk of occupational exposure to anthrax. The vaccine is reported to be 92.5% effective in protecting against cutaneous and inhalational anthrax combined. In the 1990's the US military began a mandatory vaccination program that was halted because of production problems with the manufacturer. In February 2002, vaccine production was resumed after the manufacturer met FDA requirements. Mandatory vaccination of active duty service members has not yet been resumed, and the vaccine is not currently available for use by the general public. The CDC has offered the vaccine as a part of its investigational new drug protocol, but has no recommendation as to which patients should receive it.