Biological Agents part 2


Botulism is a muscle-paralyzing disease caused by a toxin made from the bacterium Clostridium Botulinum. Botulinum toxins are some of the most poisonous substances known to humans and attack the nervous system of the body. Miniscule quantities are capable of producing disease in humans. Cases of botulism are usually associated with consumption of preserved foods, however, botulinum toxins are currently among one of the most common compounds explored by terrorists for use as biological weapons.

The bacteria that make the botulinum toxin are found naturally in many places, but it’s rare for them to make people sick. These bacteria make spores, which act like protective coatings. The spores usually do not cause people to become sick, but under certain conditions/environments, these spores can grow and produce the lethal toxin. The conditions/environments in which the spores can grow and make the toxin are:

  • Low-oxygen or no oxygen (anaerobic) environment
  • Low acid
  • Low sugar
  • Low salt
  • Within a certain temperature range
  • And within certain amounts of water

The toxin works through interfering with neural transmission in the nervous system by blocking the release of Acetylcholine. As reviewed in the Chemical section of this course, Acetylcholine is a neurotransmitter which activates muscle contraction and movement when bonded at the neuroreceptor. Without Acetylcholine, a state of paralysis begins as movement is halted.

Symptoms of Botulism poisoning include:

  • Difficulty swallowing
  • Muscle weakness
  • Double vision
  • Drooping eyelids
  • Blurry vision
  • Slurred speech
  • Difficulty breathing
  • Difficulty moving the eyes

Without treatment, the effects of the toxin progress, causing respiratory failure and eventual death.

Botulism poisoning often happen through ingestion of contaminated food products, through contamination of open wounds, and in infants usually less than 6-months-old where their gastrointestinal tract isn’t fully developed and the bacteria has a chance to germinate the toxin within the intestine. Inhalation Botulism is rare and doesn’t occur naturally. Botulism via inhalation is associated with an accidental or intentional cause which results in the release of the toxin in an aerosol form. Symptoms from inhalation can develop within 1 – 3 days depending on the amount inhaled.

Treatment of Botulism requires antitoxin administration and supportive care in hospital which could be over a long period of time. The toxin is not able to be passed on person to person. Within the prehospital environment, Botulism can often be misdiagnosed as it can have symptoms similar to a stroke.

Yersinia Pestis:

Yersinia Pestis (YP) is the bacteria responsible for the plague. It is a zoonotic bacterium often found in small mammals and their fleas. YP has the ability to disrupt and negate the cell’s communication with other immune system cells meaning it is very difficult for the body to organise an immune system response. One of the most common forms for YP to spread among humans is through flea bites. Once a flea bites, YP enters the skin and is transported via the lymphatic system to the nearest lymph nodes. Symptoms of YP usually start with an acute febrile illness along with other non-specific symptoms such as chills, head and body aches, lethargy, nausea and vomiting.

In the lymph nodes it replicates and causes the nodes to swell, become tense, and painful. The lymph node in this state is called a ‘bubo’, and this type of infection is what’s referred to as the ‘bubonic’ of bubonic plague. If left untreated, the infection can progress, causing the inflamed lymph nodes to become open sores filled with pus. The infection can further spread causing pulmonic plague and sepsis. In the bubonic phase, it is difficult for human-to-human transmission of the bacteria but is possible through contact of infectious bodily fluids or contaminated materials.

Pulmonic plague is when the infection spreads to the lungs. Pulmonic plague is highly contagious and can easily be spread through individuals inhaling vapor droplets of the infected. In pneumonic form, the plague can quickly spread to become an epidemic.

In bubonic form there is an incubation period of between 1 – 7 days before symptoms appear. Without early treatment there is a 30 – 60% fatality rate. In pneumonic form there is as little as a 24-hour incubation period before symptoms emerge, with 100% of cases being fatal without early treatment. As it is a bacterium, antibiotics are the most effective treatment. If treatment begins early then there is usually a high survivability rate.

Due to its ability to be easily spread among small mammals and their fleas, such as rats, the use of YP poses a significant threat for Bioterrorism as it could be quickly spread within urban areas. This concept has been done in the past when the Japanese dropped bombs filled with fleas infected with YP on China during WW2.


The Variola virus, or Smallpox, was a virus that existed for at least 3000 years. In that time, it has caused illness and death to millions of people. The smallpox vaccine was developed in 1796, and by 1980, the World Health Organisation had declared smallpox eradicated. Today, there are only two labs in the world that are approved to have the smallpox virus for research, the Centres for Disease Control and Prevention in the United States and the Russian State Centre for Research on Virology and Biotechnology in the Russian Federation.

Smallpox is still of a credible concern for bioterrorism as in the past, some countries made the virus into weapons which may have fallen into the hands of terrorists or other people with criminal intentions. Since the virus was eradicated, there has been no need for continued vaccination against the disease meaning a large percentage of the worlds population now doesn’t have any protection against the Variola virus. This means if it was used in a Bioterrorism plot, it could potentially spread significantly and cause a very high number of casualties.

Smallpox has around a 30% fatality rate, and spreads from person to person via contact with infected aerosol droplets from the nose or mouth when they sneeze or cough. It could also be spread through the handling of contaminated clothing and bedding. The Variola virus was deadly due to its ability to produce a protein that blocked a wide range of human interferons which are molecules produced by the immune system meant to stop viral replication. As the disease would spread in the body, in some, sepsis would set in, making the patient very poorly and even dying.

Signs and symptoms of Smallpox start with high fever, fatigue, and severe back pain. In some cases, there would be abdominal pain and vomiting. After a few days the virus produces its’ characteristic rash with bumps full of a clear liquid, which later fill with pus and finally develop a crust that dries and falls off. The rash begins on the face and hands, then spreads to the rest of the body. Lesions develop in the mucous membranes of the nose and mouth and ulcerate soon after formation. The incubation period can range between 7 – 17 days, with the patient being infectious from the point they develop a fever to when the last scab falls off.

Treatment for Smallpox requires supportive care. If early enough in the infection a vaccine can be given which may help lessen the symptoms.