By Marina Artemiou
Bacillus anthracis is a Gram-positive, endospore-forming bacterium and the principle agent of Anthrax, an extremely rare and infectious disease. Anthrax is a zoonotic disease, which is mainly associated with herbivores and domestic animals. The disease appears regularly in countries where widespread vaccination of animals is not practised, thus enabling the virus to ran rampant, infecting both livestock as well as humans who come into close occupational proximity with infected animals or animal products such as meat, skin, and bones (Goel, 2015).
The entry of Bacillus anthracis into domestic animals, including cattle and goats, is a relatively simple process. The bacteria produce endospores that can lay dormant, for extended periods of time and even centuries, and survive in unfavourable conditions in the external environment, such as in the soil, on grass and hay. When spores are ingested and enter the body of an animal or human, a place which is rich in water, sugars, and other essential nutrients, they become “activated” and transform into active proliferating cells. Rapid bacterium proliferation in turn leads to the production of a large bacterial population which can spread within the body, producing toxins and causing severe illness, tissue damage and inflammation (CDC, 2020).
Human anthrax is much less common, however B.anthracis spores can still enter the human body through a number of different routes. These include skin lesions (cutaneous anthrax), the lungs (pulmonary anthrax) and the gastrointestinal tract (gastrointestinal anthrax), where B.anthracis can germinate and give rise to the vegetative form (Goel, 2015). Despite the rarity of human anthrax in developed countries, third-world and developing countries whose economy is heavily agriculture dependent, cutaneous anthrax is still a major public health concern. However, in a surprising turn of events, cutaneous anthrax is re-emerging in several countries in Europe, Asia and Africa, due to increases in intravenous drug use (Zasada, 2018). The prevalence of this method of infection has resulted in it being granted its own name, “injectional anthrax”.
The biggest outbreak of injectional anthrax was recorded in Scotland and lasted from December 2009 until December 2010, with cases being recorded in England, Germany, Scotland, France, Wales, and Denmark. The infections were thought to be caused by heroin contaminated with anthrax spores and despite patients receiving medical treatment, the mortality rate of the outbreaks was about 35%. During the time of the outbreaks, and even up to date, injectional anthrax has been difficult to diagnose because several other common bacteria can cause skin and injection site infections while traditional microbiological detection techniques are too time consuming to allow early and accurate B.anthracis detection. As a result, healthcare providers were advised to consider all drug users which presented severe soft tissue infection, signs of meningitis or severe sepsis and signs or symptoms of inhalational anthrax , as possible cases of anthrax. Nowadays, nucleic acid based detection methods are being developed which make use of the nucleic acid sequences unique to B.anthracis, enabling both early detection and enormous specificity, to ensure that the past does not repeat itself (Zasada, 2018).
On a different note, the use of microorganisms as a means of waging war or as bioterror agents is becoming a real possibility now around the world. Any biological agent from a large range of human infection causing pathogens could be considered a potential biological weapon, however only a small handful of these fulfil the desirable criteria like ease of cultivation and dispersal, for recognition as possible biological weapons. Anthrax spores pose the biggest bioterrorism threat in the current times. This is because all the attributes of spores : high resistance to temperature, pressure, pH, ionizing radiation, and half-life of about 100 years make them a suitable bio-terror agent. All these, along with the extremely infectious and lethal nature of the active bacterium and their comparatively inexpensive production, have led to B.anthracis spores earning the status of the most desirable and lethal bio-terror agent to date (Goel, 2015). According to the CDC, B.anthracis has been placed in the high priority category, Category A, of bio-terrorism agents and poses a risk to national security because it can be easily dispersed and transmitted from person to person resulting in extremely high mortality rates and potentially majorly impacting public health and safety (CDC, 2020).
Anthrax, caused by B.anthracis spores, is still an important endemic disease of extreme public health importance in several countries of Asia, Africa and Europe and is re-emerging in some western countries due to worsening lifestyle choices, such as intravenous drug use (Mayo Clinic, 2020). Although anthrax can be cured if detected early and if the right antibiotic therapy is administered, a lot of the molecular tests which are currently available are too time consuming and their lack of specificity may result in improper antibiotic therapy administration. Collectively, the properties of B.anthracis spores that make it extremely lethal, easy to mass produce and distribute as well as the lack of rapid diagnostic testing make it the most ideal bio-terrorism agent, with the ability to cause mass amounts of harm to public health and safety.
References:
- Goel AK. (2015) Anthrax: A disease of biowarfare and public health importance. World Journal Of Clinical Cases. 16; 3(1): 20–33. Available from: doi: 10.12998/wjcc.v3.i1.20
- Centres for Disease Control and Prevention (CDC). (2020) What is Anthrax? Available from: https://www.cdc.gov/anthrax/basics/index.html [Accessed 15th March 2021]
- Zasada AA. (2018) Injectional anthrax in human: A new face of the old disease. Advances In Clinical And Experimental Medicine. 27(4):553-558. Available from: doi: 10.17219/acem/68380.
- Mayo Clinic. (2020) Anthrax. Available from: https://www.mayoclinic.org/diseases-conditions/anthrax/symptoms-causes/syc-20356203 [Accessed 15th March 2021]
Imperial Bioscience Review 