Anthrax
Introduction
Anthrax is a disease caused by the bacterium Bacillus anthracis. This bacterium is housed in a hardy spore — a cell that is dormant, but may come to life in the right conditions. Anthrax usually affects livestock, but — as the world has become fully aware — it also infects humans. A naturally occurring disease known since biblical times, anthrax has been developed into a modern biological weapon.
What can you do to protect yourself and your family against anthrax? First, don't panic. The average American's risk of exposure to anthrax remains exceedingly low, despite anthrax spores delivered through the mail in the United States in 2001. Second, arm yourself with information to fully understand this microscopic invader.
Signs and Symptoms
Anthrax occurs in three forms, with different signs and symptoms. Signs and symptoms usually occur within seven days of exposure to the bacterium, but, with inhalation anthrax, they can take up to 42 days to appear.
- Cutaneous anthrax. This form of anthrax infects the skin. It is contracted by direct contact with the bacterium, when anthrax spores enter a cut, blister or abrasion on your skin. The infection begins as a raised, sometimes itchy bump resembling an insect or spider bite. But within a day or two, the bump develops into an open, usually painless sore with a black center. In fact, the term "anthrax" comes from the Greek word for coal black, "anthracis," because of this characteristic black scab, which is actually dead tissue. Cutaneous anthrax is the most common form of the disease, accounting for 95 percent of cases, and it's also the mildest form of the disease. With treatment, cutaneous anthrax is fatal in less than 1 percent of cases. However, there is a slight danger that the infection may spread. Signs of spreading include fever, chills and swollen lymph glands central to the area of the sore.
- Gastrointestinal anthrax. It's possible to contract this form of anthrax by eating undercooked meat from an infected animal. Gastrointestinal anthrax causes sores (ulcers) within your intestines — much like the sores that appear on the skin in the cutaneous form. Initial signs and symptoms include nausea, vomiting, loss of appetite and fever, followed by abdominal pain, vomiting of blood and severe, bloody diarrhea. This form of anthrax is extremely rare. It has never been documented in the United States. But it is fatal in 25 percent to 60 percent of cases.
- Inhalation (pulmonary) anthrax. It's possible to contract this form of anthrax by inhaling anthrax spores. Initial signs and symptoms of inhalation anthrax resemble those of the flu — sore throat, mild fever, malaise, fatigue, muscle aches and mild chest discomfort. These first signs and symptoms may last for a few hours or a few days, and they may appear to subside briefly. However, soon afterwards, the disease progresses, producing a high fever, breathing problems and shock. The disease destroys lung tissue and may spread to the brain, causing meningitis. Researchers believe that inhalation anthrax is fatal in approximately 75 percent of cases, even with appropriate treatment. However, of the 11 people infected with inhalation anthrax in the United States in 2001, six survived.
Causes
Anthrax isn't new. Some historians believe anthrax was one of the Egyptian plagues at the time of Moses.
Anthrax disease is caused by a rod-shaped bacterium, Bacillus anthracis, which normally resides as a spore in the soil. These spores are extremely hardy. They're resistant to sunlight and have been known to survive in soil for many years. Anthrax spores remain dormant until they find their way into a host to infect — an animal or a human.
Anthrax primarily affects wild and domestic livestock — such as sheep, cattle, horses, goats and camels — that contract intestinal anthrax by eating spores from the soil. Anthrax once was common in most areas where livestock are raised. But in modern times, animal vaccination programs have greatly reduced the natural occurrence of the disease among both animals and humans in much of the world.
Outbreaks of animal anthrax still occur in places that don't have widespread livestock immunization programs, such as Central and South America, eastern and southern Europe, Asia, Africa, the Caribbean, and the Middle East. Naturally occurring anthrax is rare in the United States.
Historically, most human cases of anthrax occurred as a result of exposure to infected animals or their meat or hides. In fact, anthrax used to be known as woolsorters' disease because people who worked with wool in the 18th century often contracted inhalation anthrax from handling spore-contaminated wool in enclosed factory spaces.
Treatment
Treatment for all three forms of anthrax depends on oral or intravenous (IV) antibiotics. Treatment is most effective when started as early as possible.
Some strains of anthrax may be more responsive to one type of antibiotic than to another. Ciprofloxacin (Cipro), doxycycline and penicillin are FDA-approved for treatment of anthrax in adults and children. However, your doctor may prescribe other antibiotics or a combination of antibiotics.
These medications work by killing the anthrax bacteria. However, antibiotics may fail in inhalation anthrax once symptoms become severe because the bacteria may already have released large amounts of toxin that aren't affected by antibiotics. Scientists are working to develop an anthrax antitoxin that could neutralize the toxin produced by anthrax bacteria.
If you've been exposed to anthrax, your doctor will likely prescribe a 60-day course of antibiotics. If you have inhalation anthrax, you'll likely be hospitalized and treated with intravenous antibiotics.
Anthrax isn't spread person to person. So a person with anthrax doesn't have to be quarantined or isolated. If you were in contact with someone with anthrax, you'll need to be treated only if you were exposed to a source of anthrax infection.
Prevention
In addition to treating anthrax, antibiotics can prevent infection in anyone exposed to anthrax. Ciprofloxacin and doxycycline are FDA-approved for post-exposure prevention of anthrax.
The government is working to increase the nation's supply of antibiotics, in the event of a large-scale anthrax attack. Since Sept. 11, 2001, the CDC has expanded the National Pharmaceutical Stockpile (NPS) to include more antibiotics and medical supplies, additional pediatric supplies and antibiotics, as well as antidotes for chemical agents. These supplies are strategically placed so medical supplies can be delivered throughout the United States quickly.
The NPS program is also responsible for storing and transporting the anthrax vaccine, to ensure rapid distribution of vaccines in an emergency.
Anthrax vaccine
An anthrax vaccine for animals was developed in 1881. The FDA approved a human vaccine in 1970, which has mostly been used by military personnel. The human vaccine consists of three shots given two weeks apart followed by three additional shots given at six, 12, and 18 months. Annual booster shots are recommended to maintain immunity.
The human anthrax vaccine doesn't contain live anthrax bacteria, so it can't cause the illness. Side effects may include soreness at the injection site, a flu-like reaction and possibly more serious allergic reactions. The anthrax vaccine isn't recommended for children, pregnant women or older adults. It's an effective, but not a 100 percent protective vaccine.
The vaccine isn't available to the public. Instead, the vaccine is reserved for:
- Active-duty U.S. military personnel who are deployed to areas with high risk of exposure to anthrax
- People who work with anthrax in a laboratory setting
- People who handle potentially infected animal products in areas of the world where anthrax is a threat to livestock
- People who work with imported animal hides or furs from areas with a high incidence of anthrax
Avoiding contact with infected animals
In countries where anthrax is common and vaccination levels of animal herds are low, it's wise to avoid contact with livestock and animal products and to avoid eating meat that hasn't been properly slaughtered and cooked.
Other preventive measures include carefully handling dead animals suspected of having the disease and providing good protection when processing hides, fur, wool or hair.
Keeping the mail safe
Letters containing anthrax have been mailed in the United States. As a result, the U.S. Postal Service continues to take measures to keep the mail safe. For example, state-of-the-art Biohazard Detection Systems were installed in 50 major mail-processing facilities in 2004. These systems provide a new level of protection through early warning if biohazards are detected.
Informations obtained from National Institute of Health.