Anthrax

What is anthrax?

Anthrax is a life-threatening infectious disease that normally affects animals, especially ruminants (such as goats, cattle, sheep, and horses). Anthrax can be transmitted to humans by contact with infected animals or their products. In recent years, anthrax has received a great deal of attention as it has become clear that the infection can also be spread by a bio terrorist attack or by biological warfare. Anthrax does not spread from person to person.

What causes anthrax?

The agent of anthrax is a bacterium called Bacillus anthracis. While other investigators discovered the anthrax bacillus, it was a German physician and scientist, Dr. Robert Koch, who proved that the anthrax bacterium was the cause of a disease that affected farm animals in his community. Under the microscope, the bacteria look like large rods. However, in the soil, where they live, anthrax organisms exist in a dormant form called spores. These spores are very hardy and difficult to destroy. The spores have been known to survive in the soil for as long as 48 years.

How is anthrax contracted?

Anthrax can infect humans in three ways. The most common is infection through the skin, which causes an ugly sore that usually goes away without treatment. Humans and animals can ingest anthrax from carcasses of dead animals that have been contaminated with anthrax. Ingestion of anthrax can cause serious, sometimes fatal disease. The most deadly form is inhalation anthrax. If the spores of anthrax are inhaled, they migrate to lymph glands in the chest where they proliferate, spread, and produce toxins that often cause death.

How common is anthrax?

Anthrax is now rare in humans in the United States and developed countries. It still occurs today, largely in countries lacking public-health regulations that prevent exposure to infected goats, cattle, sheep, and horses and their products. In the last few years, there have been rare cases of anthrax in people exposed to imported animal hides used to make drums. Drum players, drum makers, and their family members have been infected in this way. The major concern for those of us in western countries (who don't play drums) is the use of anthrax as an agent of biological warfare.

How long is the incubation period with anthrax?

The incubation period (the period between contact with anthrax and the start of symptoms) may be relatively short, from one to five days. Like other infectious diseases, the incubation period for anthrax is quite variable and it may be weeks before an infected individual feels sick.

What kinds of diseases does anthrax cause?

There are three forms of disease caused by anthrax: cutaneous (skin) anthrax, inhalation anthrax, and gastrointestinal (bowel) anthrax.

CUTANEOUS ANTHRAX

The cutaneous (skin) form of anthrax starts as a red-brown raised spot that enlarges with considerable redness around it, blistering, and hardening. The center of the spot then shows an ulcer crater with blood-tinged drainage and the formation of a black crust called an eschar. There are swollen glands (lymph nodes) in the area. Symptoms include muscle aches and pain, headache, fever, nausea, and vomiting. The illness usually resolves in about six weeks, but deaths may occur if patients do not receive appropriate antibiotics.

INHALATION ANTHRAX

The first symptoms are subtle, gradual and, flu-like (influenza). In a few days, however, the illness worsens and there may be severe respiratory distress. Shock, coma and death follow. Inhalation anthrax does not cause a true pneumonia. In fact, the spores get picked in the lungs up by scavenger cells called macrophages. Most of the spores are killed. Unfortunately, some survive and are transported to glands in the chest called lymph nodes. In the lymph nodes, the spores that survive multiply, produce deadly toxins, and spread throughout the body. Severe hemorrhage and tissue death (necrosis) occurs in these lymph nodes in the chest. From there, the disease spreads to the adjacent lungs and the rest of the body. Inhalation anthrax is a very serious disease, and unfortunately, most affected individuals will die even if they get appropriate antibiotics. Why is this so? The antibiotics are effective in killing the bacteria, but they do not destroy the deadly toxins that have already been released by the anthrax bacteria.

GASTROINTESTINAL ANTHRAX

Now rare, anthrax of the bowels (gastrointestinal anthrax) is the result of eating undercooked, contaminated meat. The symptoms of this form of anthrax include nausea, loss of appetite, bloody diarrhea and fever followed by abdominal pain. The bacteria invade through the bowel wall. Then the infection spreads throughout the body through the bloodstream (septicemia) with deadly toxicity.

How is the diagnosis made of anthrax?

The history, including the occupation of the person, is important. The bacteria may be found in cultures or smears in cutaneous (skin) anthrax and in throat swabs and sputum in pulmonary anthrax. Chest X-rays may also show characteristic changes in and between the lungs. Once the anthrax is disseminated, bacteria can be seen in the blood using a microscope. Of course, if anthrax is deliberately spread, the manifestations of the disease may be unusual. Indeed, in the bioterrorism attack in the U.S. in 2001, anthrax spores were spread through the postal system as a white powder mailed with letters.

How is anthrax treated?

In most cases, early treatment can cure anthrax. The cutaneous (skin) form of anthrax can be treated with common antibiotics such as penicillin, tetracycline, erythromycin, and ciprofloxacin (Cipro). The pulmonary form of anthrax is a medical emergency. Early and continuous intravenous therapy with antibiotics may be lifesaving. In a bioterrorism attack, individuals exposed to anthrax will be given antibiotics before they become sick. A vaccine exists but is not yet available to the general public. Most experts think that the vaccine will also be given to exposed individuals who are victims of a bioterrorist attack. Of note, anthrax is a reportable disease. That means that local or state health agencies must be notified if a case of anthrax is diagnosed. These agencies can better characterize the anthrax so that the affected individual can receive the most effective treatment for that particular organism

How can anthrax be prevented?

Public-health measures to prevent contact with infected animals are invaluable. There is a vaccine available for people at high risk (such as veterinarians, laboratory technicians, employees of textile mills processing imported goat hair, and members of the armed forces). The Department of Defense and the U.S. Centers for Disease Control and Prevention are working very hard to prevent a bioterrorist attack and to be prepared to deal with the consequences if one occurs. For anthrax and other infectious diseases, vaccines with greater efficacy and fewer side effects are under development. Currently, most vaccines are given by injection into fat or muscle below the skin. Early studies in experimental animals are showing promise for an oral vaccine for anthrax. Obviously, a pill is easier to take than a shot, and the pill may even be a safer and more effective route of administration.

Anthrax At A Glance

• Anthrax is an infection by bacteria transmitted from animals.
• Anthrax causes skin, lung, and bowel disease and can be deadly.
• Anthrax is diagnosed by cultures from infected tissues.
• Anthrax is treated by antibiotics.
• Anthrax can be prevented.
• Sadly, the greatest threat of anthrax today is through a bioterrorist attack.
• Federal, state, and local agencies are working hard to deal with this bioterrorist threat.