Anthrax: a scientific look at the tiny bacterium that has ignited huge public health concerns

With anthrax recently becoming a major threat to America's safety, there has been much unease in the world of science causing researchers around the country to dive into discovering ways of safegaurding against the dangerous white powdery substance, the form that is known to have threatened groups of America in the past month.

Anthrax is an acute infectious disease that can be found in nature. It is caused by the bacterium Bacillus anthracis, which forms spores and occurs in the vertebrates of herbivores such as cattle and sheep. If a human is exposed to the infected animal or it's tissue, he can become infected cutaneously, gastrointestinally, or through inhalation. Although uncommon in the United States, the spores can live in the soil of farming regions for many years and humans can become infected from even handling the infected animal products or eating undercooked meat from infected animals.

There are varied symptoms of anthrax infection depending on the manner in which it was contracted. The most common manner has been cutaneous (skin), through which about twenty percent of untreated cases result in death. he symptoms include a bump that looks like an insect bite but develops into an ulcer with a black area in the center and swelling of the lymph glands in areas surrounding the ulcer. This is treatable with antimicrobial therapy.

Intestinal infection of anthrax is characterized by nausea, loss of appetite, vomiting, fever, abdominal pain, vomiting of blood, and severe diarrhea. This form of the disease results in death in approximately 40 percent of all cases.

The form of infection that is most feared is through inhalation. Initially the symptoms resemble a common cold, but in days a human will undergo severe breathing problems and can go into shock. Inhalation is usually fatal. Infection occurs when spores enter the lungs and migrate to the lymph nodes. There they change to bacterial form and multiply to produce toxins causing the mentioned symptoms. The toxins are responsible for destroying structures in the chest and causing bleeding.

Possibly even more feared, is the fact that anthrax can also be engineered to enhance the deadly effects is taking its hold on our country in the face of the recent terrorist attacks. Anthrax is very easy to manufacture and can be easily spread throughout the air to cover a large area. Therefore, the threat of infection by inhalation is very serious and very dangerous.

In America, a vaccine for anthrax was developed in the 1950's and 1960's when there was a high threat to American troops in Korea and Southwest Asia. It was licensed by the Food and Drug Administration in 1970 and has since been given to veterinarians, workers in wool factories and livestock workers among others. The way the vaccine works is to help the immune system fight against the growth of bacteria and the production of the toxins that lead to disease and death.

Since humans cannot be used in clinical trials for the vaccine in research, rhesus monkeys were used to examine the effectiveness of the vaccine. 25 monkeys were vaccinated with 2 doses and challenged with anthrax aerosol 8-38 weeks later to which all survived. 10 monkeys were vaccinated at zero and two weeks then were challenged with anthrax aerosol two years later. Nine of them survived. 10 monkeys were vaccinated only one time and challenged with anthrax aerosol six weeks later from which all survived. 20 monkeys vaccinated at zero and four weeks then were challenged with anthrax aerosol 10 to 20 weeks later. 18 survived.

Recent findings by researchers at Harvard Medical School were released just a couple of weeks ago as to their study of a drug that neutralizes the deadly toxins caused by the anthrax infection. This drug was tested on rats as they were injected with ten times the lethal dose of anthrax toxin along with the newly developed toxin inhibitor. The rats did not experience symptoms for as long as one week whereas they normally would have dies within a few hours of this exposure. These findings are evidence that a drug such as this can be a possible ally against anthrax.

The problem with antibiotics is that they cannot kill the toxin that the bacterium secretes. The administration of the drug is futile if the toxins are already present in large amounts since they are the cause of the symptoms that lead to death. The toxins are actually composed of protease (protein-digesting enzyme) and seven small pieces attach to the host cell to form a pore. The protease can slide through this pore into the cell to destroy the inside of the cell. The researched antitoxin is a series of more than 20 linked copies of a small protein. They can latch onto the pore to prevent the protease from entering the cell.

There is also the possibility of using an altered form of the protein that forms the pore as an antitoxin. R. John Collier, from Harvard, writes that, "It would be hard for a bioterrorist to find a strain of anthrax that could resist either approach, because the toxin has only a few probably inconsequential differences from strain to strain."

There are many medical advances on the frontier in regards to the treatment and prevention of anthrax. With the United States budget on Anti-Terrorism increased from the $11 billion spent last year, the research will continue and we will see many advances in the near future.