Biotech Watch

Anthrax

What Is Anthrax?

Anthrax is a disease caused by the bacterium Bacillus anthracis, which is housed in a hardy spore. The disease 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 recently become a biological weapon of concern.

Anthrax occurs in three forms:

Cutaneous anthrax. This form infects the skin, causing a sore with a black center. It occurs when a cut, blister or other skin wound comes into contact with anthrax spores. Left untreated, up to 20 percent of cases of cutaneous anthrax progress to a dangerous bloodstream infection called septicemia, which can be fatal.
Intestinal anthrax. You can contract this form by consuming meat from an infected animal. About 25 percent to 60 percent of untreated cases of intestinal anthrax result in death.
Inhalation anthrax. This most deadly form of the disease occurs when you inhale enough anthrax spores to infect the lungs. Once the infection has spread, inhalation anthrax is fatal in about 90 percent of cases.

Fortunately, all three forms can be prevented or treated with antibiotics. However, to be most effective, treatment must begin early. An anthrax vaccine exists, but unlike antibiotics is in short supply.

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 recent anthrax cases in the United States beginning in October 2001. Second, arm yourself with information to fully understand this microscopic invader.

Coping with war

Signs and Symptoms

Signs and symptoms of anthrax vary depending on how the disease was contracted. People can contract any of three forms of anthrax. Signs and symptoms of the various forms are as follows:

Cutaneous anthrax. You can contract anthrax by contact of the bacterium with an open wound. Anthrax spores can enter a cut, blister or abrasion on the skin, causing a localized skin (cutaneous) infection at the site, typically within a week to 12 days of exposure. 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 characteristic black center. In fact, the term anthrax comes from the Greek word for "coal black," anthracis, because of this black scab, which is actually dead tissue. Cutaneous anthrax is the mildest form of the disease. It's effectively treated with antibiotics. Shortly after antibiotics are started, the wound begins to heal, possibly leaving a scar. A slight danger with cutaneous anthrax is that the infection may spread, signs of which include fever, chills and swollen lymph glands near the area of the sore. With treatment, cutaneous anthrax is fatal in less than 1 percent of cases.
Intestinal anthrax. You can contract anthrax by eating undercooked meat from an infected animal. Intestinal anthrax causes sores (ulcers) within the intestines — much like the sores that appear on the skin in the cutaneous form. The first signs and symptoms of intestinal anthrax generally show up within a day to a week after eating contaminated meat. Initial signs and symptoms include nausea and vomiting, loss of appetite and fever followed by abdominal pain, vomiting of blood and severe, bloody diarrhea. You may also develop sores in your mouth and throat in addition to abdominal signs and symptoms. Untreated intestinal anthrax can be fatal, but with antibiotic treatment, it rarely is.
Inhalation (pulmonary) anthrax. You can contract anthrax by inhaling enough anthrax spores. The spores, once lodged in the respiratory tract, can take anywhere from a day, to a week, to 2 months to become active. Once they become active, signs and symptoms develop. Initial signs and symptoms resemble those of the flu or a cold — sore throat, mild fever, malaise, fatigue, muscle aches and mild chest discomfort. These first signs and symptoms may last for a few hours to a few days before they may appear to subside briefly. However, soon after — within 3 days of onset of symptoms — the disease progresses, producing a high fever and breathing problems. The disease destroys lung tissue and may spread to the brain causing meningitis. Antibiotics can reduce the risk of death, especially if started within the first few days of symptoms.

Causes

Anthrax isn't new. Anthrax is believed to have been one of the Egyptian plagues at the time of Moses. It's just never made as many headlines before.

Anthrax disease is caused by a rod-shaped bacterium, Bacillus anthracis, which normally resides as spores in the soil. Each bacterium changes into a spore in which it hibernates until it finds its way into a host to infect — an animal or human. Anthrax spores are extremely hardy. They're resistant to sunlight and have been known to survive in soil for decades.

Anthrax spores are invisible to the naked eye, odorless and tasteless. The spores measure between 1 and 5 microns in size. That's small, considering 1 micron is one-thousandth of a millimeter. The spores are so small that millions would fill but a thimble.

Anthrax primarily affects farm animals — sheep, cattle, horses, goats and pigs. Like humans, animals can contract three forms of anthrax. They can develop cutaneous anthrax if spores come in contact with a cut or sore on their hide. They contract intestinal anthrax by eating spores from soil. They can also inhale anthrax spores and develop inhalation anthrax. In animals, anthrax is almost always fatal.

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 anthrax still occur in countries — such as Mexico, South America, eastern and southern Europe, Asia, Africa, the Caribbean and the Middle East — that don't have widespread livestock immunization programs. In the United States, naturally occurring anthrax is rare. However, a few cases of animal infection with anthrax have most often been reported in Texas, Louisiana, Mississippi, Oklahoma and South Dakota.

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 1800s often contracted cutaneous anthrax from handling spore-contaminated wool.

Anthrax as a biological weapon
To date, the worst documented outbreak of inhalation anthrax in humans occurred in Russia in 1979. Anthrax spores were accidentally released from a laboratory near the town of Sverdlovsk, killing 68 people. Beginning in October 2001, cases of inhalation anthrax have been reported in the United States.

Several countries — including the United States, Britain, Iraq, Germany, Japan and the former Soviet Union — are believed to have experimented with anthrax as a biological weapon. It's suspected that Iran, Libya, North Korea and Syria also are pursuing germ warfare capabilities.

Anthrax raises concerns as a biological weapon because:

It's not difficult to obtain. Anthrax cultures are used in biological research. Samples of anthrax exist at some universities, research laboratories, military laboratories, zoos and public health clinics worldwide. In addition, anthrax theoretically could be isolated and grown from the remains of an animal that died of anthrax or from nearby soil. An individual or group with knowledge of microbiology and the right equipment could grow anthrax in a relatively short period of time.
It's highly lethal. Experts calculate that 100 kilograms (220 pounds) of anthrax aerosolized over a city on a clear, calm night could kill 130,000 to 3 million people — making such an attack as lethal as a hydrogen bomb. The small size of anthrax spores means they would be likely to infect people indoors as well as those outdoors.
It's hardy. Anthrax spores are resistant to environmental damage. During World War II, the British government experimented with anthrax on an island off the coast of Scotland. More than 40 years later, spores survived in abundance on the island. To clean up the island, workers had to remove tons of topsoil and soak the remaining ground with a formaldehyde mixture.

People intent on creating widespread anthrax infection would most likely spread anthrax by spraying it or releasing it into a ventilation system. However, making anthrax into a form that can be aerosolized requires growing a large number of spores, drying them and combining them with a powdery substance. That's difficult for the perpetrators to do, and they may contaminate themselves. In addition, the release of anthrax spores could be difficult to control once deployed because of the wind, making anthrax a less effective weapon of mass destruction.

Anthrax spores come in different sizes. The smaller the size, the more easily the spores can make it into the body upon inhalation to cause illness. There are also hundreds of naturally occurring strains of anthrax, some which are more resistant to antibiotics than others. Genetically altered strains could prove more difficult to treat. However, it takes advanced skill to produce anthrax of uniform size or of increased virulence.

Potentially, animals could be purposely infected with anthrax. But animals with anthrax die very quickly, and their meat turns blackish in color, so it's unlikely that infected animals would ever make it to or be used in a meatpacking plant. There's little information available about the risks of food or water being contaminated directly with anthrax spores.

For now, experts say that biological agents such as anthrax are used more as a threat against individuals, such as by sending anthrax through the mail, rather than threats against large groups.

Risk Factors

Anthrax isn't contagious. People who get inhalation anthrax, for example, don't exhale spores. There are no reports of the disease spreading from one person to another.

To contract anthrax, you must come in direct contact with anthrax spores. However, you can be exposed to anthrax spores and not become infected. Your risk depends on the amount of exposure and the virulence of the strain of anthrax to which you're exposed. People who test positive for anthrax spores in their nasal passageways, for example, may never develop inhalation anthrax.

When To Seek Medical Advice

For anthrax spores to be used as a biological weapon, they have to be processed into a powderlike form that will disperse in the air. Refined anthrax spores form a fine, white dust. Crude preparations have a brownish tint like sand and are clumpier. Powder that contains anthrax spores could be mailed in a letter and dispersed when the letter is opened. However, a lot of innocuous substances in our environment come in powder form, from sugar to plaster dust.

If you believe that you're at risk of anthrax exposure — for example, you work in an environment where anthrax has been detected — immediately notify authorities for testing. If you develop signs and symptoms of the disorder following exposure to animals or animal products in parts of the world where anthrax exists, seek prompt medical attention.

Symptoms of influenza — a common illness during the fall and winter months — resemble those of early inhalation anthrax. If evidence suggests that you may have been exposed to anthrax and you develop signs and symptoms of infection, see a doctor for evaluation and care.

Screening And Diagnosis

Unlike a bomb, the damage of a large-scale anthrax attack — if it were to happen — wouldn't be immediately and readily apparent. It would take the outbreak of many anthrax cases to raise suspicion that an attack had occurred.

If exposure to anthrax is suspected, field tests can help determine whether a substance contains anthrax spores or whether an area — such as a mailroom, desk or ventilation system — may be contaminated.

In addition, various tests can help doctors determine whether a person has been exposed to anthrax or has the disease.

Field tests
If you find a suspicious powder that you think may contain anthrax, immediately contact local law enforcement authorities. In turn, they can contact hazardous-material teams trained to test for materials such as anthrax.

Wearing protective suits, the team collects samples of the substance and samples from surfaces that may have been contaminated. The samples are then checked for signs of Bacillus anthracis bacteria.

Testing for anthrax in the environment traditionally hasn't been easy, because anthrax bacteria can easily be confused with other bacteria. Anthrax is a member of the large Bacillus family of bacteria. But so are germs that cause mild food poisoning and other germs that are harmless to people.

Typically, testing for anthrax occurs in stages. The first rapid field tests give an idea within a few hours whether anthrax contamination is a possibility. But the tests aren't definitive. The next stage is to have samples cultured in a lab. This involves incubating a sample in a lab dish containing special nutrients that spur any bacteria present to grow. The test takes several hours to several days until it becomes apparent whether anthrax is present. If anthrax is found, scientists then use a DNA fingerprinting technique to identify the specific strain of anthrax. The entire process may take several days.

Testing for anthrax has improved with the introduction of a new rapid field test for anthrax, developed by researchers at Mayo Clinic, Rochester, Minn., and Roche Laboratories of Indianapolis. The new test can detect anthrax in a suspicious substance (or in a person's blood) in less than an hour. The test should be available in select laboratories nationwide by early December 2001, and later in laboratories in other countries.

With the new rapid field test, samples are still collected from a potentially contaminated area. But the samples can then be sent immediately to a laboratory that can run the rapid test. The new test uses PCR (polymerase chain reaction) technology to detect the DNA of anthrax bacteria and is highly effective in detecting anthrax.

Identifying the DNA of anthrax also helps identify the strain of anthrax present — information that may help determine where the anthrax may have originated. A record of each known naturally occurring strain of anthrax and where it exists naturally is kept on file at the U.S. Los Alamos National Laboratory in New Mexico.

The new rapid DNA test also can be used to detect anthrax infection in humans. The laboratory test should help enable doctors to begin more timely treatment of people who have been exposed to anthrax, and should help alleviate undue anxiety for people who haven't been exposed.

If anthrax is found in the environment, then the areas — such as a mailroom, desk or ventilation system — that are contaminated are sterilized with special washes.

Should you have your home or office checked for anthrax? Some home-testing kits for anthrax are marketed, but these require some skill to use and can't provide definitive results. Some U.S. companies have hired private firms to test their buildings for anthrax. But, overall, scientists say that random checking of homes and offices is neither necessary nor practical. Nationwide, a limited although growing number of people possess anthrax-testing expertise, and they're needed to monitor areas at known risk.

Human tests
In addition to examining you and inquiring about your health status and where you work, doctors can administer tests that may determine whether you've been exposed to anthrax or have the disease.

Doctors will want to rule out other, much more common conditions that may be causing your symptoms, such as influenza (flu) or common causes of pneumonia. For example, rapid flu tests are available in many doctors' offices that can help doctors quickly diagnose a case of influenza.

Tests to detect and diagnose anthrax include:

Skin biopsy. A sample of a suspicious lesion on your skin can be sent to a lab to check for microscopic evidence of cutaneous anthrax.
Sputum testing. To diagnose inhalation anthrax, respiratory secretions can be cultured to check for the presence of anthrax bacteria.
Blood tests. If you have possible symptoms of any form of anthrax, doctors can order blood tests. Blood samples are sent to a lab and can be cultured to check for the presence of anthrax bacteria in the blood. Blood tests can also check for antibodies to anthrax, as your body tries to fight off the infection on its own. However, antibodies may not develop until several weeks after exposure. With the availability of Mayo Clinic's new rapid anthrax test, blood samples can be tested for anthrax much more quickly than in the past. In less than an hour, doctors may be able to answer "yes" or "no" to the question of whether a person has anthrax.
Chest X-ray. Doctors may look for changes on a chest X-ray that may help indicate inhalation anthrax. Since inhalation anthrax infects both the lungs and lymph nodes in the chest, there's often a very characteristic appearance on chest X-ray.
Endoscopy and stool samples. To diagnose intestinal anthrax, doctors may examine your throat or intestines with the aid of an endoscope — a thin, flexible tube with a video camera at its tip that can be inserted into your throat or intestines to check for anthrax lesions. Stool samples can be tested for the presence of anthrax bacteria.
Spinal tap. Sometimes doctors may need to take a sample of spinal fluid to confirm a diagnosis of anthrax meningitis. This involves doctors inserting a needle into the spinal canal and drawing out fluid for testing.

There's no definitive test for exposure to anthrax, in the absence of overt infection. Doctors can swab the inside of your nose. Airborne anthrax spores can become trapped in nasal passages. However, the presence of anthrax spores in your nose doesn't mean that you will become ill. In addition, a negative test doesn't rule out exposure. The Centers for Disease Control and Prevention (CDC) isn't recommending the use of nasal swab testing to diagnose inhalation anthrax.

Because there's no definitive test for exposure to anthrax, doctors may place anyone who may have been exposed to a contaminated area on a course of prescription antibiotics to prevent the disease.

If a case of anthrax is suspected or confirmed, doctors have been advised to contact local and state health officials immediately. This helps alert government and health leaders — and the public — of a possible outbreak.

Emergency response teams trained to respond to biological attacks are being assembled in major U.S. cities. Efforts also are under way to increase doctors' knowledge of how to recognize and treat anthrax.

Spinal tap (lumbar puncture)

Treatment

Doctors treat anthrax with oral or intravenous (IV) antibiotics.

Some strains of anthrax may be more responsive to one type of antibiotic than another. Doctors can use several antibiotics to treat or prevent the present strain of anthrax infections in the United States. They include:

Penicillin
Tetracycline (Achromycin V, Apo-Tetra)
Doxycycline (Doryx, Monodox)
Amoxicillin (Amoxil, Polymox)
Ciprofloaxacin (Cipro)
Erythromycin
Chloramphenicol (Chloromycetin)

All three forms of anthrax can be treated with antibiotics. Cutaneous anthrax is the most responsive to treatment. Intestinal anthrax also responds well to treatment. Inhalation anthrax, the deadliest form, also can be treated. But, whatever the form, treatment is most effective when started as early as possible. Untreated inhalation anthrax is often fatal, but death is far less likely with early, appropriate care.

Antibiotics work by killing the anthrax bacteria. Anthrax spores that are inhaled, ingested or come in contact with breaks in the skin cause infection by transforming into active, virulent bacteria. For example, in inhalation anthrax, the spores enter the upper respiratory tract or lungs and undergo their transformation into bacteria there. The bacteria then migrate to the lymph nodes and into the bloodstream and other parts of the body, multiply by the millions and eventually produce toxins that cause severe damage to tissues.

Antibiotics usually fail in inhalation anthrax once symptoms become severe because, by that time, the bacteria already have released large amounts of toxin that aren't affected by antibiotics. However, scientists are trying to develop an anthrax antitoxin that — unlike antibiotics — could neutralize the toxin produced by anthrax bacteria.

If you've been exposed to anthrax, your doctor likely will prescribe an antibiotic. If you have any form of anthrax, you may need to take antibiotics for as long as 2 months. If you have inhalation anthrax, you likely will be hospitalized and treated with high-dose antibiotics.

Anthrax isn't spread person to person. So a person with anthrax doesn't have to be quarantined or isolated. Those who are in contact with the person need to be treated only if they were exposed to a source of anthrax infection.

Prevention

Antibiotics can prevent infection in anyone exposed to anthrax. The U.S. government is working to increase the nation's supply of antibiotics, in the event of a large-scale anthrax attack.

Currently, the CDC houses enough antibiotics to treat several million people. There are other large stores of antibiotics, as well. The maker of ciprofloxacin, Bayer, has markedly increased production of the drug in response to recent anthrax outbreaks. Other antibiotics also can be mass-produced quickly, if needed on short notice.

In addition to antibiotics, there's an anthrax vaccine.

Anthrax vaccine
An anthrax vaccine for animals was developed in 1939. The human vaccine was approved by the Food and Drug Administration (FDA) in 1970. The human vaccine consists of three shots given 2 weeks apart followed by three additional shots given at 6, 12, and 18 months. Annual booster shots are recommended to maintain immunity.

The human vaccine could conceivably be given immediately to anyone exposed to or who has anthrax and repeated 2 weeks later to augment protection from antibiotics.

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 flulike reaction and possibly more serious allergic reactions. The anthrax vaccine isn't recommended for use in children, pregnant women or older people. It's an effective but not 100-percent protective vaccine.

The vaccine isn't currently available to the public. Instead, the vaccine — which is in short supply — is reserved for:

Active-duty U.S. military personnel who might be involved in conflict. Currently, only Special Forces receive the shot.
People who work with anthrax in a laboratory setting.
Agricultural workers in areas of the world where anthrax is a threat to livestock.
People who work with imported animal hides or furs from high-incidence countries.
Travelers at risk of exposure to animals or animal products in high-incidence countries.

The only manufacturer of the anthrax vaccine for humans is Bioport Corp., in Lansing, Mich. The company had stopped shipments of anthrax vaccine, but it recently renovated its plants and plans to begin producing the vaccine again. In addition, two newer anthrax vaccines are in clinical trials. However, it may be years before the United States can build up a large stockpile of anthrax vaccine for use in the general public. The anthrax vaccine for animals can't be used in humans.

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 avoid eating meat that hasn't been properly slaughtered and cooked.

Other means of preventing the spread of anthrax include carefully handling dead animals suspected of having the disease and providing good protection when processing hides, fur, wool or hair.

Irradiating the mail
Letters containing anthrax recently have been mailed in the United States. Since then, the U.S. Postal Service is considering the use of devices that irradiate mail — using radiation to kill microorganisms — in mail-processing centers across the country. In fact, the U.S. Postal Service has already begun placing mail destined for Washington, D.C., addresses through irradiation equipment in an effort to sanitize it.

It's hoped that irradiation will kill anthrax spores in unopened envelopes that are passed through the device. The equipment is similar to that used in the food industry to kill bacteria in food.

Irradiation doesn't make letters or packages radioactive or dangerous in other ways — although it could prove damaging to computer disks, film and credit cards sent through the mail. But how successful irradiating machines would be and how practical their use, considering that the postal service handles billions of pieces of mail a year, is still under study.

Self Care

What can you do to protect yourself and your family from anthrax? You can arm yourself with information and answers:

Should you call your doctor and ask to be vaccinated against anthrax? No. The anthrax vaccine isn't available to the public at this time. Your health would be better served by receiving the influenza vaccine. The flu kills an estimated 20,000 Americans annually.
Should you call your doctor and ask for a prescription for antibiotics? No. Stocking up on antibiotics for anthrax will only have the effect of depleting the supply for people who need them for more immediate reasons. Ciprofloxacin and other antibiotics should be used only when there's a medical need as determined by a doctor. In addition, widespread use of antibiotics to prevent anthrax could increase the chances of antibiotic-resistant strains of anthrax and other bacteria developing.
Should you buy a gas mask? It's unclear whether masks that you can buy over-the-counter (OTC) would do any good in an anthrax attack. Unlike gas masks worn by hazardous-material teams, most OTC gas masks can't filter out anthrax spores. In addition, anthrax can't be seen or smelled. If it were released, you wouldn't see a cloud of anthrax coming toward you, so you wouldn't know when to put on a gas mask. Even if you were to wear a gas mask, it wouldn't necessarily be clear to you when it would be safe to remove the mask. The government isn't recommending that people buy gas masks.

Coping Skills

Recent anthrax scares may have left you feeling jittery. However, a few cases of anthrax — as scary as they are — don't represent an epidemic. The most prudent course of action right now is to keep a healthy perspective and to stay on top of current events.

While anthrax should be taken seriously, the threat shouldn't be exaggerated. There are more than 270 million people living in the United States. To date, relatively few American citizens have contracted anthrax.

Events in the United States after Sept. 11, 2001, have increased public awareness of the risk of anthrax and other bioterrorism agents. U.S. government and health officials are on high alert for outbreaks of anthrax, and plans are under way to address potential large-scale outbreaks. For example, the U.S. government is studying high-tech sensors that could provide early detection of an anthrax attack.

Government and health officials urge people not to panic but instead to use common sense. To reduce your exposure to anthrax and to feel more secure:

Report any suspicious substance to local authorities. If you come in contact with a clearly suspicious substance, don't sniff, touch, taste or look closely at it. Don't try to clean it up. Move away from the substance. Alert others in the area about the substance. Leave the area, close any doors, and take actions to prevent others from entering the area. If possible, shut off the area's ventilation system. Those exposed to the substance should wash their hands with soap and water. Then report the substance to local law enforcement authorities. Seek additional instructions for exposed or potentially exposed persons.
Report any suspicious mail to local authorities. Don't open a suspicious envelope or package. Don't shake or empty the contents. Don't carry the envelope or package, show it to others, or allow others to examine it. Don't sniff, touch, taste, or look closely at it or any contents that may have spilled. Instead, put the envelope or package on a stable surface. Then alert others in the area about the suspicious envelope or package. Leave the area, close any doors and take actions to prevent others from entering the area. If possible, shut off the area's ventilation system. Those who had contact with the suspicious item should wash their hands with soap and water. Then report the suspicious mail to local authorities. Seek additional instructions for exposed or potentially exposed persons.
Leave a contaminated area. If there's any question that a room has been contaminated by an unknown, airborne agent, turn off fans or ventilation units in the area. Then leave the area immediately. Close the door or section off the area to prevent others from entering. Summon emergency help. If possible, also shut down all air-handling systems in the building.

If you're concerned about coming in contact with anthrax spores while opening your mail at home or work, wash your hands with soap and water when you're finished to reduce your risk.

— November 5, 2001 —

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