Anthrax

Anthrax may have originated in Egypt and Mesopotamia as early as 700 BC. Anthrax was thought to be the fifth plague of Egypt in Moses's ten plagues because it affected horses, cattle, sheep, camels, and oxen—Anthrax is described in many ancient writings of famous poets from 70 to 19 BC. Anthrax is known to affected Ancient Rome and Greece. Before the first clinical case of cutaneous Anthrax in 1752, Anthrax was only known through historical accounts of people telling stories. The next event of Anthrax involved Robert Koch, a scientist who identified the life cycle of the anthrax bacteria. He successfully developed what is now known as Koch's postulates, which show a connection between a particular microorganism and a disease. After this, doctors started putting together the link between Anthrax and the animal hair industry ("Anthrax | CDC," 2020).

Anthrax is a zoonotic infection that has affected places worldwide. Anthrax is a dangerous zoonotic illness but is not contagious from person to person. The threat of Anthrax is mainly in underdeveloped countries, where workers are being exposed to Bacillus anthracis spores (Sweeney et al., 2011). However, many practices have been implemented to help make industrial outbreaks rare. The following paragraphs will detail the spread of Anthrax, typical places where it occurs, and Anthrax's possibilities for the future.

Animals frequently contract Anthrax, whereas human cases are much less common. Anthrax has four main variations: injectional, cutaneous, gastrointestinal, and inhalation (“Anthrax | CDC,” 2020). These four types and their characteristics will be covered in this writing. Many people who are regularly exposed to Anthrax do not exhibit any symptoms, while others do so as soon as two days after exposure (Pantha et al., 2018). If Anthrax is discovered promptly, it can be treated with antibiotics that target the bacteria that cause infection (Hendricks et al., 2022).

Anthrax is a gram-positive, large, aerobic, rod-shaped bacteria that is a toxin-mediated zoonotic disease (Kamal et al., 2011). Anthrax is caused by Bacillus anthracis bacteria spores that are taken up by macrophages and enter regional lymph nodes, germinate, and replicate (Bagamian et al., 2013). The spore form of anthrax cannot be killed by the immune cells in the lungs or lymph nodes (Pantha et al., 2018). This bacteria needs a high concentration in a host to survive (Sweeney et al., 2011). In vitro, the organism exists as single or in short chains but forms long chains in vivo (Kamal et al., 2011). Anthrax has an incubation period of thirty-six to seventy-two hours (Bagamian et al., 2013). However, the Bacillus anthracis spores can be destroyed if boiled in water for up to ten minutes (Kamal et al., 2011). If not killed, the bacteria spores can survive for years with no host.

Bacillus anthracis has two major virulence factors, which are encoded on separate plasmids; these are the protective antigen and edema toxin. The protective antigen binds to target cell receptors and provides a means for edema factor and lethal factor to enter the cell. This antigen forms the lethal toxin that causes death in the infected. The edema toxin leads to the loss of chloride ions and water from the cell and the subsequent formation of massive edema in surrounding tissue. The Bacillus anthracis causes the lysis of macrophages and the release of inflammatory mediators (Kamal et al., 2011).

Anthrax-affected animals live worldwide and include both domestic and wild animals. Herbivores are the natural reservoir host for anthrax (Kamal et al., 2011). Herbivores tend to eat plants close to the ground, which causes them to be the natural reservoir host (Bakhteeva and Timofeev, 2022). These plants may be contaminated with anthrax infection or Bacillus anthracis spores. Anthrax is usually found in wildlife and livestock; people become infected when interacting with these animals. All warm-blooded animals are susceptible to the Bacillus anthracis bacteria (Kamal et al., 2011). These animals are at risk because anthrax naturally occurs in soil and can survive there for long durations of time (Stella et al., 2020).

Anthrax can be transmitted from animal to animal or from animal to person (Kamal et al., 2011). Anthrax is commonly found in agrarian communities in underdeveloped countries (Sweeney et al., 2011). Workers dealing with animals or animal products are susceptible to contracting the Bacillus anthracis bacteria (Pantha et al., 2018). These workers are at high risk because these countries do not routinely vaccinate their grazing animals, which the workers are constantly coming into contact with. Vaccinating these animals helps to control the outbreak of anthrax (“Anthrax | CDC,” 2020).

Anthrax is a very deadly and widespread bacterial disease for many reasons. It is only studied when fatalities have recently occurred in humans or animals due to an outbreak (Bagamian et al., 2013). Anthrax rarely occurs in people. However, traveling increases someone's chances of encountering Anthrax spores. Another way someone's chances of coming into contact with anthrax increases is if a human works with infected animals or animal products. A human should not eat raw or undercooked meats that have a chance of being contaminated with anthrax spores ("Anthrax | CDC," 2020).

Types of jobs that put humans at risk for contracting anthrax are farmers, veterinarians, livestock handlers, diagnostic laboratory workers, wool mill workers, slaughterhouse workers, tanneries, and people who work with animal products (Pantha et al., 2018). However, if one of these workers does contract the bacteria, they are not isolated from others because it has never been documented that anthrax spreads through horizontal transmission (Hendricks et al., 2022). Nonetheless, some employees regularly exposed to anthrax do not report any symptoms. This is particularly common among those who work in mills that process goat hair (Pantha et al., 2018). Anthrax is spread from country to country by imported wool and cashmere contaminated with anthrax spores. Cases in the United States have been related to imported animal hides that contain anthrax spores (Levi et al., 2003).

Severe illnesses take place in humans and animals; however, it is very uncommon in America. Transmission can occur in the form of cutaneous contact, the most common form of Anthrax (Kamal et al., 2011). Examples include a percutaneous infection from biting flies, ingestion, or inhaling Bacillus anthracis spores (Bagamian et al., 2013). People can breathe in or drink water that contains the spores, eat contaminated food, or get a spore in a cut on their skin. Animals get the bacteria by breathing in spores or ingesting the spores contained in contaminated soil, water, or plants. (“Anthrax | CDC,” 2020)

Symptoms depend heavily on which type of Anthrax a person or animal has been exposed to. Symptoms can take one day to more than two months to appear in the infected person or animal (“Anthrax | CDC,” 2020). The CDC lists the different possible symptoms based on the type of Anthrax listed in the images below. Some common symptoms of Anthrax are nonspecific behavioral changes followed by the sudden death of the infected person or animal (Bagamian et al., 2013).  

There are four types of Anthrax infection. The first is cutaneous Anthrax, the most common but least dangerous (Kamal et al., 2011). Cutaneous Anthrax occurs when spores are introduced to breaks in exposed skin areas, such as a cut. Cuts allow the bacteria to enter into the break in the skin. Inhalation anthrax occurs in workers that handle spore-contaminated animal hides, and this is commonly transported when the animal hides are traded between countries. The next type is gastrointestinal Anthrax, typically related to ingesting spores from contaminated meat. Finally, the newest form of Anthrax, injectional Anthrax, is common in injection drug users, such as heroin users. Injectional Anthrax occurs when the spores germinate at the inoculation site, and the bacteria’s capsule facilitates local spread. (Sweeney et al., 2011)

Anthrax is most commonly found in agricultural regions such as Central and South America, Sub-Saharan Africa, Central and Southwestern Asia, Southern and Eastern Europe, and the Caribbean. There are only about two thousand cases worldwide annually (Sweeney et al., 2011). No test can tell someone if they have been exposed to Anthrax (Levi et al., 2003). A public health investigation is the only way for a person to find out if they have been exposed (“Anthrax | CDC,” 2020).

A person can become infected on any part of their exposed skin, including the arm, hand, head, or neck. In the cases of cutaneous Anthrax, a well-known symptom is a black eschar. Black eschar is formed from the necrosis and drying of the ulcer (Kamal et al., 2011). Some people that are routinely exposed to Anthrax show no symptoms at all. It is not understood why some people experience symptoms, and others do not (Pantha et al., 2018).

Anthrax can survive for an extended period of time, a decade, in soil, which is the primary way that animals contract the bacteria. The bacteria get into the soil from decaying animal carcasses that died due to the bacteria. Then the bacteria use water as transportation to help the bacteria spread. Anthrax spores are highly resilient (FINKE et al., 2020). Bacillus anthracis bacteria can turn dormant if it comes in contact with oxygen and atmospheric air. Once these spores become dormant, they can spread undetected until the conditions are more ideal for the bacteria to become active. Warm temperatures may increase the risk of an anthrax outbreak. A change in environmental conditions is related to an increased risk of an outbreak (Stella et al., 2020).

Transmission pathways of anthrax bacteria can be from cutaneous contact, percutaneous infection from biting flies, ingestion, or inhalation of Bacillus anthracis spores (Bagamian et al., 2013). Infected carcasses of animals that have died from Anthrax are a way that both animals and people get exposed to the bacteria. Infected animals have a high case fatality rate (Stella et al., 2020). Humans contract Anthrax by coming in contact with an infected animal or animal product. People can also breathe in the spores, drink or eat contaminated food or water, or get spores in a cut on their skin. The spores enter their bodies, and the bacteria then multiply and spread in the body (“Anthrax | CDC,” 2020).

Global warming may cause more outbreaks of Anthrax because it is a climate-sensitive infection (Stella et al., 2020). The presence of Anthrax spores can be sent to microbiological testing, which will determine if there is a chance of an outbreak (Levi et al., 2003). Routine culture with confirmation by real-time PCR is most frequently used to diagnose Anthrax. Workplace outbreaks are becoming uncommon because of the emphasis on yearly animal vaccination, disinfecting processes, and improved factory ventilation(Sweeney et al., 2011)

Anthrax is common in countries that do not routinely vaccinate their grazing animals. Vaccines are recommended yearly for livestock in areas where Anthrax has been found in the past (“Anthrax | CDC,” 2020). Since all warm-blooded herbivores are susceptible, anthrax outbreaks in animals are highly common. These outbreaks will become more frequent in the northern hemisphere as the planet warms (Kamal et al., 2011).

In herbivores, the anthrax incubation period is thirty-six to seventy-two hours (Bagamian et al., 2013). However, if it is caught early, there are ways to treat Anthrax. Doctors can prescribe Ciprofloxacin or Doxycycline to prevent Anthrax after exposure. These antibiotic treatments can last from sixty to one hundred days. Another treatment, once the spores have activated in the body, is antitoxins. Antitoxins target anthrax toxins in the body and attack them to rid the body of the bacteria. There is much improvement in patients that receive these treatments in time. Scientists are also working on further diagnostic testing that will help in the ability to detect anthrax exposure rapidly (“Anthrax | CDC,” 2020). This will help doctors and public health workers better prepare for an anthrax outbreak (Hendricks et al., 2022).

Anthrax is very rare in people, and the vaccine for Anthrax is not permitted for the general public. The Anthrax Vaccine Absorbed (AVA) is able to prevent against Anthrax. However, only three groups of people can receive the vaccine, laboratory workers that work with Anthrax, people who handle animals or animal products, and certain members of the United States military. The vaccine is given five times over the course of eighteen months, and an annual booster is given to help protect people from the bacteria. The vaccine has no live anthrax bacteria, which means it can not give people Anthrax (“Anthrax | CDC,” 2020).

Anthrax can be used as a biowarfare agent and is highly likely to be used in a bioterrorism attack because it has been used before. This is because Anthrax spores are found very easily in nature. The spores can also be produced in a lab and used in the attack. Anthrax bacteria spores last a long time in the environment which can be ideal for an attack. Anthrax can be quickly released without people knowing because the spores are microscopic. The spores can be turned into powders, sprays, food, and water (“Anthrax | CDC,” 2020).

Biowarfare is a great fear when it comes to Anthrax. In 2015, the FDA approved vaccine use for post-attack exposure to Anthrax. People eighteen to sixty-five years of age will be able to get three shots over four weeks after exposure and a sixty-day course of antibiotics. The vaccine is used to help prevent the disease in people that have already been exposed to the Anthrax bacteria. People who have had an allergic reaction to a past dose of the Anthrax vaccine are recommended not to receive the vaccine and to only have the sixty-day course of antibiotics ("Anthrax | CDC," 2020).

Injection Anthrax is the newest form of Anthrax and is common in injection drug users. Traveling is becoming even more common in the developed world and can increase someone's chances of contracting the bacteria. Industry outbreaks of Anthrax are becoming less common because of new safety regulations put in place to help reduce the chance of contracting Anthrax (Sweeney et al., 2011).