Anthrax bacteria have a high fatality rate, surviving in harsh environments, making them a dangerous biological weapon.
What is Anthrax?
Anthrax bacteria are rod-shaped. (Photo: Live Science).
Anthrax is an acute infectious disease caused by the bacterium Bacillus anthracis, which affects warm-blooded animals, including livestock, wildlife, and humans. Anthrax pandemics have occurred multiple times, primarily affecting farmers who often come into contact with infected livestock.
The most common form of infection in humans is through skin contact, where anthrax spores enter the body through open wounds. This is also the easiest form to treat, and patients typically recover completely after antibiotic treatment.
The National Library of Medicine in the U.S. states that the anthrax bacteria are most dangerous when they enter the respiratory system, often seen in workers handling animal hair and hides. Spores typically enter the alveoli in the lungs and are destroyed by the immune system; however, some spores may invade lymph nodes, develop into bacteria, and release toxins that destroy cells.
If not treated, toxins can accumulate in the lungs, leading to a series of severe issues. Victims may experience flu-like symptoms for several days, which can progress to pneumonia, respiratory failure, hypotension, meningitis, and multiple organ failure.
Symptoms of anthrax on human skin. (Photo: AAP).
The mortality rate for this form of anthrax can reach up to 92%. However, it is also the most difficult form to contract. A person must inhale 8,000 to 10,000 spores to become infected, and these spores must penetrate deep into the lungs before causing harm.
The final form is gastrointestinal anthrax, which occurs when a victim consumes meat from infected animals. The incubation period typically ranges from one to 60 days, leading to symptoms such as fever, cough, chills, nausea, and vomiting. This is the rarest form in the U.S., often with a mortality rate of 20-60%, but it can be completely cured with antibiotics if detected early.
What are the Symptoms of Anthrax?
Anthrax can be transmitted to humans through the following methods:
Cutaneous Anthrax
Cutaneous anthrax is characterized by skin lesions and results from exposure to spores through the care of infected animals or contact with contaminated animal hair, hides, meat, or bones. This form accounts for 95% of anthrax cases.
When infected, lesions typically appear on the head, neck, and limbs. The initial skin lesions present as itchy, painless bumps, appearing 3-5 days after spore exposure. Within 24-36 hours, they develop into blisters that necrotize in the center, drying out to leave a distinctive black scab, accompanied by surrounding swelling with red-purple blisters.
If the necrotic lesions become purulent, painful, and the patient develops a fever, the infection may have become secondarily infected, often by staphylococci or streptococci.
The surrounding area may swell and be painful, which can persist even after scab formation. Lesions on the neck can cause swelling and may contribute to breathing difficulties.
Respiratory Anthrax
This form of respiratory anthrax is rare in nature but may be more common if anthrax spores are used as a biological weapon. When anthrax spores are aerosolized, they can spread widely in the atmosphere and enter the respiratory tract, leading to a high mortality rate.
Respiratory anthrax, or inhalational anthrax, begins abruptly, typically 1-3 days (but can extend from 1-60 days) after inhaling a large quantity of anthrax spores. Initially, there may be no specific respiratory symptoms or difficulty in breathing, but mild fever and a non-specific cough may be present.
Patients may experience chest pain early on and improve temporarily before rapidly progressing to severe breathing issues. Severe inhalational anthrax is marked by high fever, difficulty breathing, rapid respiration, cyanosis, excessive sweating, vomiting blood, and severe chest pain that can mimic a heart attack. This form often leads to death due to the excessive production of toxins by the bacteria overwhelming the circulatory system.
Inhalational anthrax occurs when spores are inhaled into the lungs, which can happen if a person handles animal products containing the pathogen. Once inhaled, the bacteria multiply and can spread their toxins into the bloodstream, affecting multiple organs. Infections may reach the liver, spleen, and kidneys, potentially causing systemic severe infections and death. This form is also referred to as septicemia following inhalational infection.
Gastrointestinal Anthrax
Gastrointestinal anthrax is very difficult to recognize; patients may go into shock and die within 2-5 days after the onset of the disease. Symptoms can include fever, diffuse abdominal pain with rebound tenderness, constipation, or diarrhea after ingesting spores or eating meat from infected animals. Stools may appear coffee-ground or contain blood. After 2-5 days, ascites may develop with persistent abdominal pain.
Patients with gastrointestinal anthrax may exhibit vomiting, hematemesis, fatigue, loss of appetite, abdominal pain, bloody diarrhea, and fever. This form is challenging to diagnose because it can easily be confused with other infectious diseases. It may result in oral or pharyngeal ulcers. A person with a history of eating contaminated products may experience a sore throat or difficulty swallowing. This form has a high mortality rate.
Bacteria can transmit anthrax from animals to humans.
Meningeal Anthrax
Meningeal anthrax can cause complications of any form and spread throughout the central nervous system and brain. This is a rare but highly fatal complication.
The most common route of entry for anthrax bacilli is through the skin, but it can also occur with gastrointestinal and respiratory forms. Patients will almost certainly die within 1-6 days after onset, even with aggressive antibiotic treatment.
In addition to typical symptoms such as purulent meningitis, meningitis from anthrax may also present with muscle pain, agitation, seizures, or coma. Neurological deterioration occurs rapidly, followed by death.
Septicemic Anthrax
Septicemic anthrax is an overwhelming infection of Bacillus anthracis in the entire circulatory system. This can be a complication of inhalational anthrax. Internal organs may become blackened due to the spread of the infection in the blood. The bacteria multiply in the blood and spread, infecting many red blood cells.
Most cases of septicemic anthrax occur following inhalational anthrax. The number of bacteria released from the liver and spleen into the lungs overwhelms the body’s defenses, leading to the production of a large amount of lethal toxin, clinically manifesting as shock and death.
In summary, anthrax is a dangerous acute infectious disease caused by spores or the bacterium Bacillus anthracis. It infects humans through open skin wounds, consumption of infected animal meat, or inhalation of bacterial spores.
To prevent the disease, people are advised not to handle, slaughter, or consume meat from infected livestock. Those frequently in contact with sick or dead animals (of unknown causes) should wear boots, rubber gloves, long pants, and long-sleeve shirts; avoid exposing unprotected skin or damaged skin to livestock.
After contact with animals, everyone should wash their hands and any exposed skin with soap and water. If someone in the household shows symptoms of anthrax, it is essential to take the victim to the nearest medical facility for timely treatment and notify local authorities to investigate and manage the outbreak.
Dangerous Biological Weapons
However, when used for military purposes, anthrax bacteria become one of the most dangerous biological weapons in the world, according to former U.S. Assistant Secretary of Defense Andrew Weber.
Anthrax bacteria can be easily cultured in laboratories and have a high survival capability. They can remain dormant for many years before infecting a host, reactivating, and proliferating. A tiny amount of anthrax bacteria, equivalent to the size of a fingernail, has the potential to kill over 10,000 people.
In World War I, Nordic countries used anthrax pathogens to attack the armies of Tsarist Russia. It also resurfaced when the British attempted to destroy large herds of cattle belonging to Nazi Germany during World War II.
Anthrax was used in the terrorist attacks in the U.S. in 2001. (Photo: NTI).
In 1993, a Japanese religious group spread anthrax bacteria in a public area in Tokyo, but it resulted in no fatalities. Just eight years later, a series of letters containing anthrax spores were sent to media offices and two U.S. senators, resulting in five deaths and 17 infections.
The anthrax vaccine has been developed since 1881, significantly reducing the number of infections and deaths caused by natural means.
Although anthrax spores can survive for a long time, they cannot withstand more than 30 minutes in boiling water or 5 minutes under an iron’s heat. This is an effective method to eliminate anthrax bacteria from common items.
