Immunizations Bioterrorism

Since 9/11, citizens of the world at large have been faced with the specter of a new kind of warfare: bioterrorism. The idea of defending a population from the scourge of deliberately inflicted diseases such as smallpox, bubonic plague, anthrax, tularemia and other biological agents seems almost the stuff of fiction.

The “Captain Trips” virus of Stephen King’s epic work The Stand paints a stark yet realistic view of what an unchecked biological threat could do to a population. Current research focuses on the development of vaccines and other strategies to identify, contain, and protect against bioterrorism attacks.

Smallpox

Use of the smallpox vaccine ended in the US in 1972 after the disease was considered to be eradicated from our country. The smallpox vaccine is a live vaccine that uses a “pox-like” viral strain known as vaccinia.

Serious risks appear to be very slight in healthy individuals who do not have any medical conditions that could be aggravated by vaccination. Muscle stiffness in the neck, slight dizziness for short periods of time, and skin rashes are some of the most common side effects. However, an estimated one to two individuals out of every one million injected would die from an adverse reaction if a widespread vaccination program were to take place. Smallpox vaccine risks are higher for people who have dermatitis or other skin conditions, individuals who are immunocompromised, and for those who have heart conditions.

Current recommendations are for the immunization of medical workers, particularly those who risk contact with infected patients, and military personnel. If a threat were to become more eminent, the Centers for Disease Control and Prevention (CDC) assures us that enough smallpox vaccine is on hand to provide widespread protection.

Anthrax

Known formally as the bacterium Bacillus anthracis, anthrax is another major biological agent that can occur in three forms: gastrointestinal, cutaneous, and inhalational. Most cases can be effectively treated with antibiotics if administered early enough. Prevention strategies are aimed at both “passive” immunization and “active” immunization. The passive treatment uses the injection of preformed antibodies against anthrax, whereas the active treatment uses a traditional vaccine to stimulate antibody production. In light of recent world events, research is ongoing to develop these methods and make them available on a large scale. Clinical trials are underway to test the safety and efficacy of these vaccines.

The Black Plague

The Black Plague, which wiped out countless millions in Asia and Europe in the 14th Century, was caused by a bacterium Yersinia pestis. Because the bacteria is carried by rodents and fleas, simple measures such as increased sanitation have all but eradicated this disease. However, the severity of infection with this microorganism has people wondering about its potential use in bioterrorism. Although a plague vaccine is not currently available, antibiotic treatment is effective if administered early enough.

Zoonotic Diseases as Bioterrorism Threats

Aside from plague, other zoonotic diseases (diseases transmitted from animals to humans) have been a focus of bioterrorism research. From conditions as mild as ringworm, to life-threatening illnesses such as rabies, tuberculosis and tuleremia, providing vaccines for domestic animals will become a necessary line of defense.

Tularemia, a disease similar to plague, has no true immunization formula and has been estimated to cause 250,000 casualties with 19,000 deaths from a mere 50 kilograms of aerosol spray. Though explored as a biological weapon prior to World War II, tularemia has only recently resurfaced as a bioterrorism concern.

Perhaps no zoonotic disease is more frightening than the Ebola virus. Very little is known about the Ebola virus although it was first identified as a disease nearly thirty years ago, and it seems that the primary animal reservoir is monkeys and chimpanzees. Without specific knowledge of how it is transmitted or what course of treatment can cure its victims, the Ebola virus represents a major threat throughout the world. Medical research and clinical trials will be necessary to develop pharmaceutical responses in the form of both vaccines and treatments.

Other Bioterrorism Threats

Food poisoning, either through chemical application or the use of natural agents such as botulism, are other bioterrorism concerns that lack specific immunizations. People contract botulism by eating food containing the toxin. Improving the inspection of processing plants can limit food poisoning, but preventing the deliberate insertion of botulism in food supplies requires antiterrorism measures. Treatment against botulism is achieved through the use of an antitoxin.

Ricin is a by-product obtained during the processing of castor beans. This poison can cause multiple organ damage in humans by blocking the synthesis of cellular proteins. Ricin can potentially attack humans by inhalation, food or water poisoning, or injection. For ricin to be a legitimate threat would require a large-scale deliberate mass production of the poison. No antidote is available yet, and treatment would consist of life-support measures.

Other chemicals known as nerve agents are also man-made compounds capable of threatening large groups of people. Some examples are VX and sarin nerve gas. These gases are odorless and when released as vapor or used to contaminate food or water sources can have a widespread effect. Two separate terrorist attacks in 1994 and 1995 were carried out in Japan using sarin nerve gas. The health effects from these gases are dose-dependent but potentially lethal if the exposure is substantial and the antidote is not provided in time.