Risk Assessment: Tools, Techniques, and Their Applications

20.4 Anthrax Example

The causative agent is Bacillus anthracis, a gram-positive bacilli commonly found in soil and carried by herbivores such as cows and sheep (6). As a spore-forming organism, it can lay dormant in the soil for years. There are three forms of anthrax. The first is gastrointestinal anthrax. This is usually secondary to infected meat. When aerosolized, anthrax can present as a viral disease of the upper respiratory tract with fever. The spores are inhaled and brought into the lungs. From there, they are carried to the mediastinal lymph nodes and release the active bacteria. This carries a risk of 100% mortality without very early use of antibiotics. In the anthrax letter attacks that occurred in 2001, there were five fatalities. These were all from inhalational anthrax. Death was after 7 days of symptoms and the deaths occurred without prompt use of appropriate antibiotics. Treatment includes ciprofloxacin or doxycycline. Cutaneous anthrax develops from spores being introduced into an open wound through the skin. Initially, a painless blister develops. Then, a black necrotic lesion develops. Prior to the common use of antibiotics, this would lead to death in one-fifth of all cases.