This is Sarah Long. And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today we tell about the disease anthrax.
Eight weeks have passed since the terrorist attacks in New York and Washington, D-C. Now Americans are concerned about recent discoveries of the deadly bacteria that cause the disease anthrax.
The presence of anthrax has been confirmed in a series of incidents in Washington, D-C, New York City, New Jersey, Florida and other states. Anthrax particles were found in letters that had been mailed to several places, including major news organizations and congressional offices. This has led to the closing of several government office buildings and mail centers.
Federal investigators say evidence suggests that the anthrax was sent through the mail in an organized act of biological terrorism. They say the attacks may be linked to the terrorist attacks in the United States on September Eleventh.
Several people have died of anthrax. Several other people have been infected with a severe form of the disease. Many other people have been tested. Many people are taking medicines to protect against the disease if anthrax was found in buildings where they work.
Only a small number of people so far have been infected with anthrax. However, these incidents are spreading fear and confusion across the country. They also are raising many questions about the disease.
Anthrax is a disease of warm-blooded animals. It most commonly affects cattle and other animals that eat plants. However, it also can affect people who deal with infected animals or animal products. Anthrax can not be passed from one person to another.
Anthrax is caused by the bacterium Bacillus anthracis. It is found naturally in the environment. The bacteria have protective coverings called spores. The spores are like seeds. They can live for hundreds of years in the soil. They can survive through extreme heat, lack of rain, and other severe environmental conditions.
Anthrax can be found anywhere in the world. It is most common in developing countries, where it affects animals.
Animals can get the bacteria while eating plants by loosening anthrax spores in the soil. The animal eats or breathes in the spores and may become infected. Animals can be given vaccine medicines to prevent the disease.
In people, the disease can appear in three forms: cutaneous anthrax, intestinal anthrax and inhalation anthrax.
Cutaneous anthrax is the most common kind of infection. People can become infected this way if the bacteria enter through a cut in the skin. The disease is most often found among people who work with infected animals or animal products. Cutaneous anthrax causes a painful, black area on the skin. However, it rarely causes death.
Intestinal anthrax is caused by eating infected meat. It can cause high body temperature, vomiting and stomach pain. It often can be cured.
The most severe form of the disease is inhalation anthrax. This happens when a person breathes the spores into the lungs. Inhalation anthrax is most often found among people who work with animal hair and wool in areas where the disease affects animals.
Inhalation anthrax is deadly if a person breathes in thousands of extremely small spores. Large spores may get caught in the nose or throat, where they are less dangerous. But the small spores can travel to the lungs.
The body's defense system against disease attacks some spores, but carries others to the lymph nodes in the chest. Once there, the spores change into a deadly form. The bacteria grow and spread to the rest of the body. This may take a day, a week or as many as two months. As infection spreads to the rest of the body, the bacteria produce poisons that enter the blood. These poisons can cause a build-up of fluids in the lung, tissue destruction and death.
Doctors treat infected people with medicines called antibiotics. They have proven effective in fighting the disease in most cases. Antibiotics can treat the disease if it is discovered early. The antibiotics ciprofloxacin, penicillin and doxycycline are all effective treatments. An anthrax infection is especially dangerous because people do not know they have been infected until signs begin to appear. Signs of the disease usually begin to appear within a few days. Chest X-rays can help doctors tell if a person has inhaled anthrax.
Early signs are similar to the disease influenza. They may include high body temperature, muscle pain and a cough. These are usually followed by severe breathing problems and death if the disease is not treated.
Anthrax spores are hard to kill. Antibiotics halt the development of the disease by fighting the bacteria as they grow from the spores. However, antibiotics do not fight the poisons that the bacteria produce. To work best, the antibiotics need to be active in the blood for as long as spores might be present in the lungs or in other places in the body. Health officials say people should take antibiotics for sixty days to treat or protect against anthrax infection.
There is a vaccine designed to prevent some forms of anthrax. However, it is not being given to the public at this time. The United States government has a limited supply for members of the armed forces.
Anthrax is considered a major threat because of its ability to be used as a biological weapon. Biological weapons are living microorganisms. Biological and chemical agents are most effective when spread into the air. These agents are often placed in bombs or artillery shells that are designed to explode into the air and spread poisons over an enemy. Many biological and chemical agents have no color, smell or taste. So an attack could take place without the victims knowing it.
Experts say anthrax is one of the easiest biological agents to manufacture. It can be grown in a laboratory. It spreads easily through the air over a large area. It can be made into a form that is easily inhaled. It is easily stored and is dangerous for a long period of time. It also costs very little to make.
Anthrax has been used in laboratory experiments for more than one-hundred years. Many scientists have used anthrax for traditional research purposes. The bacteria also have been genetically changed for biological weapons research. Several countries have experimented with anthrax in their biological weapons programs. They include the United States and the former Soviet Union.
Anthrax spores in nature stick together in particles too large to be breathed in. Experts say that the individual anthrax spore is extremely small, about one micron wide. For example, two-thousand spores lined up would measure only two millimeters. Particles that are five microns or bigger are usually trapped in the upper part of the respiratory system. To be an effective weapon, anthrax spores are reproduced so that they are smaller than five microns. Experts say making such anthrax spores requires special laboratory equipment and a great deal of skill.
Until now, there has not been much information about treatment for human anthrax. The only research that had been done was based on animal studies. Until last month, only about eighteen cases had been reported in the United States since Nineteen-Hundred. The last incident took place twenty-three years ago. The victims were mostly people who processed wool, goat hair or animal skins.
As a result, officials at the Centers for Disease Control and Prevention in Atlanta, Georgia say there is only limited medical experience for treating human anthrax. In fact, they say there have been no controlled human studies on treating the deadliest form of anthrax, the inhaled version.
Biological weapons were sometimes used with horrible effects in several wars during the Nineteen-Hundreds. However, they have rarely been used by terrorists. Experts say biological weapons are among the most serious threats to national and international security.
This SCIENCE IN THE NEWS program was written by Cynthia Kirk. This is Sarah Long. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.