Biological Agents Biological agents are living organisms or products of living organisms that cause disease in human beings. Of all pathogens (the dangerous microorganisms that cause disease), experts believe that the following are examples of those most likely to be used in a biological attack, mostly based on factors such as ease of acquisition and delivery, and their lethality. Click on diagram for more information on chemical agents.

Toxins Rather than being living organisms, toxins are chemicals produced by living organisms such as bacteria, plants, and animals. Some toxins are the most deadly chemicals known to man; however, they are never contagious.

Bacteriological agents Pathogenic bacteria are single-celled microorganisms that can cause disease. They can generally reproduce on their own and are susceptible to treatment with antibiotics.

Viral agents Viruses are microorganisms that contain genetic material but require a host cell in order to reproduce. They are much smaller than bacteria and are not susceptible to treatment with antibiotics. A few viral species are susceptible to chemical anti-viral agents.

Mycotoxins are naturally occurring chemicals produced by fungi growing on grain, feed, or food. Detrimental to animals and humans, their toxicity ranges from causing death to chronic diseases, cancer, and sterility.

Mycotoxins may be ingested, inhaled, or absorbed into the skin. The trichothecene group of mycotoxins can act on the skin in a relatively short time (minutes to hours). Eye and skin irritation, blisters, nausea, and shortness of breath are among the symptoms.

There are no effective antidotes for mycotoxins, so most treatment is supportive.

Staphylococcal Enterotoxin Type B is produced by the bacteria Staphylococcus aureus and is normally acquired through ingestion of improperly handled food. Although SEB is not highly lethal, it is capable of incapacitating up to 80% of personnel in an area under attack.

Symptoms include non-specific flu-like symptoms such as fever, chills, and headache. In the case of ingestion, further symptoms are nausea, vomiting, and diarrhea. When SEB is inhaled, symptoms can include a nonproductive cough, chest pain, and difficulty breathing.

No vaccine or antitoxin is available to treat SEB before or after exposure; therefore, the only treatment is supportive therapy.

Botulinum toxin is the most poisonous chemical known to man. Produced by the bacterium Clostridium botulinum, it is a particularly dangerous biological weapon due to its high potency, lethality, and ease of transportation.

Botulinum toxin may be inhaled or ingested. The most affected body areas are the respiration system, the intestinal system, and musculature, leading to muscle paralysis in those areas.

An antitoxin may be effective in keeping patient alive. Treatment is otherwise supportive.

Ricin is a toxic protein produced by the castor bean plant, Ricinus communis.

Ricin may be inhaled, injected, or ingested, and (when inhaled) has symptoms similar to pneumonia. For this reason, it can often be mistaken for a bacterial infection.

Medications are available to flush the intestinal system of the toxin, with no guarantee of purification; otherwise, only supportive therapy is available.

Anthrax, caused by the bacterium Bacillus anthracis, is typically acquired in nature after contact with infected animals or animal products. There are two main types of anthrax exposure: cutaneous anthrax (infection on the skin) and inhalation anthrax, the latter being more lethal. Neither form of the disease is contagious.

Inhalation anthrax is more physically devastating and can cause flu-like and pneumonia-like symptoms in victims, leading to death in most cases if it is not treated early. Cutaneous anthrax results in a large black lesion on the surface of the skin at the site of infection.

If diagnosed early, anthrax can be treated with a variety of antibiotics and supportive therapy. There is also an anthrax vaccine currently administered to high-risk individuals and U.S. military personnel.

Glanders is a disease that typically affects horses, mules, and donkeys. Nevertheless, the bacterium that causes glanders, Burkholderia mallei, can also infect humans. Glanders is a candidate for biological warfare because of its tendency to trigger fatal disease with a limited number of germs.

The bacteria can enter the body through cuts in the skin or the membranes of the eyes and nose, resulting in lesions on the skin and pneumonia-like symptoms. Glanders, though a communicable disease, is not thought to be highly contagious.

A variety of antibiotics can be used to treat glanders. However, even when treated, the disease has had a high mortality rate (roughly 50%). Treatment procedures are not well established because the disease is so rare.

Plague is the infamous "Black Death" caused by the bacterium Yersinia pestis. Aerosol-dispersed plague particles can cause an outbreak of pneumonic plague, a rare, highly lethal, and contagious form of plague.

Highly contagious, the Yersinia pestis bacteria cause an infection characterized by lymph node swelling. Pneumonia and meningitis are frequently associated with the disease. The mortality rate of untreated pneumonic plague is roughly 100%.

Post-exposure treatment remains focused on supportive therapy and antibiotics. A U.S. licensed vaccine exists and appears to prevent or lessen the chances of bubonic disease development.

Q-fever generally affects sheep, cattle, and other farm animals. The disease agent, the rickettsial bacterium Coxiella burnetti, builds up in internal tissues, so veterinarians and farmers tend to be at risk. Natural human cases are rare. The disease is debilitating, but rarely lethal.

With a 2- to 14-day incubation period, patients can expect to develop pneumonia, hepatitis, high fever, or even experience vivid hallucinations.

Even untreated, most people with Q fever will recover. Treatment with a variety of antibiotics shortens the illness and results in fewer complications. A vaccine exists but is not available to the general public.

Francisella tularensis, the organism that causes tularemia, is one of the most infectious bacteria known, with as few as 10 organisms causing disease. Francisella tularensis is capable of surviving for weeks at low temperatures in water, moist soil, or decaying material. It can cause human infection through inhalation of infective aerosols, animal bites, handling infectious tissues, direct contact, or ingestion of contaminated water, food, or soil.

After an incubation period of 1-21 days, tularemia patients experience acute fever symptoms, with pneumonia developing in the inhalation form. Without treatment, respiratory failure can occur, leading to shock and eventually death.

Treatment includes antibiotics. In the United States, a vaccine has been used to protect laboratory personnel routinely working with the bacterium. However, given the short incubation period of tularemia and incomplete protection of current vaccines against inhalation tularemia, vaccination is not recommended for post-exposure prevention.

Smallpox, caused by the variola major virus, has historically been feared as one of the most serious of all diseases: It has a 30% mortality rate, there is no effective treatment, it is highly communicable, and it is physically disfiguring. Since this disease was eradicated in 1980, no one in the United States outside of the military has been vaccinated against it for more than 25 years.

After an incubation period of about 12-14 days, the patient experiences high fever and exhaustion with headache and backache sometimes followed by occasional bouts of delirium. The characteristic bliste