Biological Warfare (cont.)
William C. Shiel Jr., MD, FACP, FACR
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
IN THIS ARTICLE
Anthrax Exposure Symptoms, Signs, and Diagnosis
Anthrax bacteria occur worldwide. The United States Working Group on Civilian Biodefense and the Centers for Diseases Control and Prevention (CDC) have identified anthrax as one of a few biological agents capable of causing death and disease in sufficient numbers to cripple a developed region or urban setting. The organisms known as Bacillus anthracis may ordinarily produce disease in domesticated as well as wild animals such as goats, sheep, cattle, horses, and swine. Humans become infected by contact with infected animals or contaminated animal products. Infection occurs mainly through the skin and rarely by breathing spores or swallowing them. Spores exist in the soil and become active when the organisms in the carcass are exposed to air.
Apart from biological warfare, anthrax in humans is rare. In the United States, only 127 cases of anthrax appeared in the early years of the 20th century and dropped to about one per year during the 1990s.
Signs and Symptoms
Skin anthrax (cutaneous): Infection begins when the spores enter the skin through small cuts or abrasions. Spores then become active in the host (human or animal) and produce poisonous toxins. Swelling, bleeding, and tissue death may occur at the site of infection.
Inhalation anthrax: In inhalation anthrax, the spores are inhaled into the lungs where they become active and multiply. There they produce massive bleeding and swelling inside the chest cavity. The germs then can spread to the blood, leading to shock and blood poisoning, which may lead to death.
Mouth, throat, GI tract (oropharyngeal and gastrointestinal): These cases result when someone eats infected meat that has not been cooked sufficiently. After an incubation period of two to five days, victims with oropharyngeal disease develop a severe sore throat or sores in the mouth or on a tonsil. Fever and neck swelling may occur. The victim may have trouble breathing. GI anthrax begins with nonspecific symptoms of nausea, vomiting, and fever. These are followed in most victims by severe abdominal pain. The victim may also vomit blood and have diarrhea.
Doctors will perform various tests, especially if anthrax is suspected.
The most useful microbiologic test is the standard blood culture, which is almost always positive in victims with anthrax throughout their bodies. Blood cultures should show growth in six to 24 hours and if the laboratory has been alerted to the possibility of anthrax, biochemical testing should provide a preliminary diagnosis 12-24 hours later. However, if the laboratory has not been alerted to the possibility of anthrax, there is the chance that the organism may not be identified correctly.
Rapid diagnostic tests for anthrax and its proteins include polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and direct fluorescent antibody (DFA) testing. Currently, these tests are only available at national reference laboratories.
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