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Biomedical Terror

By Rachel Nielsen

Advanced technology affords many benefits to human beings, but it also provides instruments of mass destruction. For example, advanced biological technology may provide cures for illnesses but it also provides instruments of biological terrorism. When war involves these microscopic, deadly, biological agents, it takes on a new and frightening dimension. Human beings harnessing the power of bacteria to kill large quantities of people sounds like science fiction. Unfortunately, we now hear about use of these biological agents not only from novels, but also from newspaper stories.

Biological weapons are frightening, in part, because of limited public understanding of this type of warfare. The popular and uninformed opinion on biological warfare is that huge communities of people will be wiped out in one fell swoop by fatal infections. In this paper I will answer basic questions about biological warfare to provide a better understanding of what biological warfare means and how we can defend against it. Although biological warfare is frightening, it will not necessarily lead to the destruction of life on Earth. These infections are often fatal if untreated, but people can survive the illness if they seek appropriate medical treatment.

Merriam-Webster defines biological warfare as, "warfare involving the use of living organisms (as disease germs) or their toxic products as weapons."(2) From this definition, all pathogenic organisms are potential biological weapons. Anthrax, smallpox, plague, botulinum toxin, and tularemia all could be used. Bacteria used as biological weapons are those that are deadly, cheap, and able to infect many individuals through aerosols, or canisters that propel the bacteria into the air for the victims to breathe.

Anthrax

Weapon-grade anthrax spores have been used in the recent terrorist attacks against the United States. The perpetrators mailed anthrax spores in letters to various locations, including all three braches of the government. Five deaths resulted from this attack (8). Anthrax is an exceptionally dangerous bacterial infection. Bacillus anthracis forms endospores in the dormant phase of the organism. In contrast to the organism's active phase, these spores can survive for decades without nourishment (i.e. outside of a host). Spores develop and multiply again when they find a favorable environment. Animal or human hosts provide an environment rich in materials for B. anthracis to thrive. The spore-forming abilities of B. anthracis make it a preferred agent for biological warfare because spores are easy to make and to release into the air in mass quantities for enemies to breathe.

Anthrax spores infect inhalationally, cutaneously (on the skin), and gastrointestinally; patient-to-patient transfer is unlikely. Of these three, inhalational infection is the most deadly. The spores develop into bacterial cells in the lungs and are subsequently transported to lymph nodes via lymphatics, vessels carrying tissue fluids. As the bacteria continue to grow, they release large amounts of toxic chemicals into the host organism. In the early stages of the infection, symptoms include fevers, difficulty breathing, coughing, headaches, vomiting, chills, bodily weakness, and abdominal and chest pains. At this stage of the infection, antibiotics such as doxycycline and ciprofloxacin kill the bacteria and allow the patient to heal. Early detection is unlikely unless the doctor has reason to specifically look for B. anthracis because the early symptoms are similar to those of the cold or flu.

If the infection progresses, then the toxins produced by the bacteria cause hemorrhaging (blood escapes from blood vessels), edema (fluid escapes from the lymphatics), and necrosis (mass death of cells) in the host organism. Death can occur within 24 hours once the infection reaches this critical level. At this point, antibiotics cannot help the patient because of the high amount of toxin in the bloodstream. Early detection is essential for patient recovery.

Preventative measures, such as antibiotics and vaccinations, can and will provide a strong defense against enemies attacking with B. anthracis. A vaccination exists for anthrax, and recently the United States mandated that all individuals in the military receive one. The high cost of producing these vaccines prevents the country from offering the vaccination to the entire population. Only a wide-scale attack using anthrax will prompt the government to expend such resources. The unavailability of this vaccine leads to wide scale dependence on antibiotics. Treatment with antibiotics is effective and a more reasonable solution to an attack than every person receiving a vaccination for B. anthracis. In the event of a large-scale attack with anthrax, a regime of preventative antibiotics will need to be available in order to protect individuals exposed to the spores in their living environment (5).

Smallpox

During the French and Indian Wars, the British military used the smallpox virus as one of the first biological weapons against the Native Americans. British soldiers gave Native Americans blankets previously used by smallpox sufferers, and 50% of the members of the tribes subsequently died from this infection. Even though an effective vaccine exists for this virus now, it has again become a possible agent for biological warfare because widespread vaccination was discontinues in 1980. At this time, all naturally occurring strains of smallpox were eradicated from the Earth. Additionally, in 1999, all known sources of smallpox virus were destroyed, so hopefully it is no longer a threat (7).

Transmission of the smallpox virus occurs when the virus finds a beneficial growing environment in the individual's respiratory tract. Viruses travel to the lymph nodes, spleen, and bone marrow where they begin to multiply. Traveling in red blood cells, smallpox viruses take up residence in the skin tissue, where they proceed to infect the skin cells, causing a widespread rash. In the case of smallpox infection, the patient experiences a high fever, bodily pain, exhaustion and weakness accompanied by headache and backache within the first two weeks. During this time the rash develops into pustular lesions, and if the patient recovers these lesions leave large pitted scars. Patients typically die during the second week of infection from the large amount of viral organisms circulating in the bloodstream, which diminish the ability of the kidneys to clean the blood.

Unlike anthrax, smallpox can be transmitted from one infected person to others. This infectiousness makes it a more effective weapon because far more people can be infected by a single application of the virus. The patient is the most contagious for about a week after the rash associated with the infection appears. Scabs forming over the lesions mark the phase when the patient is no longer infectious.

Since viruses are not self-propagating, they are more difficult to use as biological weapons. The possibility of using smallpox as a biological weapon arises because many humans are susceptible to the disease, since they no longer receive vaccinations for it. As with anthrax, the most effective way to spread smallpox is as an aerosol. Isolation, observation, and attempted vaccination of all people exposed to smallpox are the only ways to deal with an outbreak. Vaccination within four days of exposure to the virus helps individuals fight off the virus. The mortality rate of untreated individuals is fifty percent, and with effective vaccination, chances of surviving smallpox infection are very great (4).

Plague

Throughout history the black plague has been one of the most devastating bacterial killers. Fleas on rats carry Yersinis pestis, the bacterial agent of the pneumonic plague. When these infected fleas bite humans, the humans develop the plague. This mode of transportation makes the bacteria extremely mobile, and human beings living in crowded places are especially susceptible to infection. Like smallpox, the plague is communicable, and can spread from one person to another. The most effective way to use Y. pestis as a biological weapon is via an aerosol that would infect all organisms that breathed in the contaminated air.

In the naturally occurring infection, Y. pestis enters the host's bloodstream after an infected flea bites the victim. The immediate symptoms are fever, chills, weakness, and extremely swollen lymph nodes. The bacteria then move to the lymph nodes where they grow and multiply, destroying the lymph nodes. Subsequently re-released into the bloodstream, the bacteria cause clots to form in blood vessels, sending the patient into shock and eventually a coma. Without lymph nodes to fight off the infection, and without antibiotic treatment, patients die of the infection at this point.

Inhaled Y. pestis presents differently in patients. The first symptoms of the inhaled pneumonic plague are cough, difficulty breathing, chest pain, presence of blood in sputum, and eventual development of severe pneumonia. The bacterium proceeds the same way through the body as naturally occurring Y. pestis infections. If victims are untreated, death usually occurs within two to six days of exposure to the bacteria.

Recommended treatment for the victims of an attack with Y. pestis is with antibiotics such as streptomycin, gentamicin, or medicines from the classes of tetracycline or fluoroquinolone. Determination of antibiotic resistance of the bacteria will dictate what antibiotic should be used to fight epidemic. To be effective, administration of antibiotics needs to happen within 24 hours of the victim's exposure to the bacteria. Since this is another bacterial infection, antibiotic treatment is extremely effective if the illness is treated early enough (6).

Botulinum toxin

Clostridium botulinum produces botulinum toxin, which makes an infection with this bacteria pathogenic. Between 1990 and 1995, the Japanese cult Aum Shinriky released botulinum toxin in downtown Tokyo, Japan on three different occasions. These unsuccessful attacks on United States military camps did not cause any deaths. This information implies that botulinum toxin is not an ideal bioterrorist agent. Also, since C. botulinum is not contagious, these bacteria would affect only the people who are exposed to the weapon itself. Again, C. botulinum would be an ineffective biological weapon for inflicting many deaths.

Two naturally occurring forms of botulism include infection caused by food-borne bacteria and infection from receiving a deep puncture wound. The third, human-devised, form of infection is inhalation botulism. Regardless of means of entry, once the bacteria has entered the system it produces botulinum toxin, which travels via the bloodstream to the neuromuscular junction, the gap between cells where electrochemical signals, by means of acetylcholine molecules, are sent from the neuron to the muscle cell. The toxin binds to the neuron, irreversibly blocking acetylcholine release, and the neuron cannot send the signal to the muscle cell that makes it move. This toxin ultimately causes paralysis. The severity of the paralysis depends on the amount of toxin absorbed into the body of the victim. Symptoms include difficulty seeing, speaking, and swallowing as the patient looses more and more control over muscular function.

The mortality due to naturally occurring botulism declined significantly from 25% from 1950-1959 to 6% from 1990-1996. Early treatment, within 12-72 hours of exposure, with equine antitoxin limits the damage to the nerve tissue and therefore plays an important role in the overall recovery of the patient. Since the toxin is not a living organism, antibiotics cannot be utilized to treat this infection. Those who survive botulism may suffer from paralysis. However, the body's ability to regenerate muscle fibers makes recovery possible. This process can take weeks to months depending on the severity of the case. While patients recover from the botulism attack they may require the assistance of a ventilator, feeding tube, and prophylactic medicines for secondary illnesses for weeks to months after exposure. At this phase in the infection, antibiotics become crucial in keeping the patient free of extraneous infections (1).

Tularemia

Tularemia, caused by the bacteria Francisella tularensis, is extremely infectious and can be contracted from exposure to as few as 10 bacteria. F. tularensis can be transmitted through the water supply and can survive for weeks at low temperatures in aquatic and terrestrial environments. This resilience makes F. tularensis an easy bacteria to distribute to a large quantity of people. Aerosol dispersion is another viable mode of using these bacteria as biological weapons. Thankfully, this infection is not very contagious.

Francisella tularensis infects hosts through the skin, mucous membranes, gastrointestinal tract, and lungs. The organism first targets the lymph nodes, lungs, spleen, liver, and kidneys, where it grows and multiplies inside macrophages, cells that play a central role in the destruction of some other bacteria, but not this one. By using the host's immune system to the infecting organism's own advantage, F. tularensis not only gains the ability to better survive the host body's defenses, but then uses the immune response to propagate its own cells. From there, the bacteria move to other organs in the host's body. Without treatment, the patient develops lung lesions. Naturally occurring airborne tularemia primarily causes a pleuropneumonic infection, characterized by inflammation of the lungs. Nonspecific early symptoms include fever, headache, chill, general body pain, runny nose, and soar throat. Within 3-5 days, more serious respiratory problems become apparent. The lungs fill up with fluid, which leads to the patient's death due to suffocation.

The FDA has not approved the vaccination for F. tularensis yet, but even if it does, approval does not guarantee the vaccine's availability to the general public. Antibiotics are effective for treating patients infected with this bacterium. Doctors usually prescribe streptomycin and gentamicin to treat F. tularensis infection. Again, treatment needs to occur early in the infection, since it otherwise kills patients very quickly with its irreversible damage to the lungs (3).

Conclusion

These five examples are just a small sample of the potential biological killers. Anthrax, the plague, and tularemia can all be combated effectively with antibiotics if the infections are caught early enough. Vaccinations for smallpox could be started again if the threat of infection becomes apparent, but this is unlikely since all of the smallpox in the world has supposedly been eradicated. The reassuring aspect of this vaccination is that it can be administered after exposure to the virus and still be effective. In the case of botulinum toxin, early detection of the infection and subsequent administration of the anti-toxin has saved lives. Even though the prospect of attacks with these biological agents is scary, defenses exist against these infections.

Also, biological weapons are not as easy to make and use as popularly believed, and therefore they will not kill as many people as other weaponry that exists. Many of the human-implemented attacks have not been successful at killing many people. The most effective outbreaks are the natural ones, and humans have not been able to replicate them.

Most importantly, individuals need to stay informed on the potential harm this type of technology can do, so that when an attack happens we will be prepared. Having this knowledge can save your life.

Works Cited

1. Amon, Stephen S., Robert Schechter, Thomas V. Inglesby, Donald A. Henderson, John G. Bartlett, Michael S. Ascher, Edward Eitzen, Anne D. Fine, Jerome Hauer, Marcelle Layton, Scott Lillibridge, Michael T. Osterholm, Tara O'Toole, Gerald Parker, Trish M. Perl, Philip K. Russell, David L. Swerdlow, Kevin Tonat, for the Working Group on Civilian Biodefense. "Botulinum Toxin as a Biological Weapon." JAMA. Vol. 285 no. 8. 28 Feb 2001. http://jama.ama-assn.org/issues/v285n8/ffull/jst00017.html (17 Oct 2001).

2. "Biological Warfare." Merriam-Webster's Collegiate Dictionary. 2001. http://www.m-w.com/cgi-bin/dictionary (17 Oct 2001).

3. Dennis, David T., Thomas V. Inglesby, Donald A. Henderson, John G. Bartlett, Michael S. Ascher, Edward Eitzen, Anne D. Fine, Arthur M. Friedlander, Jerome Hauer, Marcelle Layton, Scott R. Lillibridge, Joseph E. McDade, Michael T. Osterholm, Tara O'Toole, Gerald Parker, Trish M. Perl, Philip K. Russell, Kevin Tonat, for the Working Group on Civilian Biodefense . "Tularemia as a Biological Weapon." JAMA. Vol. 285 no. 21. 6 Jun 2001. http://jama.ama-assn.org/issues/v285n21/ffull/jst10001.html (17 Oct 2001).

4. Henderson, Donald A., Thomas V. Inglesby, John G. Bartlett, Michael S. Ascher, Edward Eitzen, Peter B. Jahrling, Jerome Hauer, Marcelle Layton, Joseph McDade, Michael T. Osterholm, Tara O'Toole, Gerald Parker, Trish Perl, Philip K. Russell, Kevin Tonat, for the Working Group on Civilian Biodefense. "Smallpox as a Biological Weapon." JAMA. Vol. 281 no. 22. 9 Jun 1999. http://jama.ama-assn.org/issues/v281n22/ffull/jst90000.html (17 Oct 2001).

5. Inglesby, Thomas V., Donald A. Henderson, John G. Bartlett, Michael S. Ascher, Edward Eitzen, Arthur M. Friedlander, Jerome Hauer, Joseph McDade, Michael T. Osterholm, Tara O'Toole, Gerald Parker, Trish M. Perl, Philip K. Russell, Kevin Tonat, for the Working Group on Civilian Biodefense. "Anthrax as a Biological Weapon." JAMA. Vol. 281 no. 18. 12 May 1999. http://jama.ama-assn.org/issues/v281n18/ffull/jst80027.html (17 Oct 2001).

6. Inglesby, Thomas V., David T. Dennis, Donald A. Henderson, John G. Bartlett, Michael S. Ascher, Edward Eitzen, Anne D. Fine, Arthur M. Friedlander, Jerome Hauer, John F. Koerner, Marcelle Layton, Joseph McDade, Michael T. Osterholm, Tara O'Toole, Gerald Parker, Trish M. Perl, Philip K. Russell, Monica Schoch-Spana, Kevin Tonat, for the Working Group on Civilian Biodefense. "Plague as a Biological Weapon." JAMA. Vol. 283 no. 17. 3 May 2000. http://jama.ama-assn.org/issues/v283n17/ffull/jst90013.html (17 Oct 2001).

7. Madigan, Michael T., John M. Martinko, and Jack Parker. Brock Biology of Microorganisms, Ninth Edition. New Jersey: Prentice Hall, 2000.

8. Thomas, Evan, and Eleanor Clift. "Who Killed Kathy Nguyen?" Newsweek 12 Nov. 2001: 30-34.