Anthrax is a life-threatening infectious disease caused by Bacillus anthracis that typically affects animals, especially ruminants (such as goats, cattle, sheep and horses). Anthrax can be transmitted to people through contact with infected animals or their products. Anthrax has received much attention in recent years as it has become clear that the infection can also be spread by a bioterrorist attack or biological warfare. Anthrax does not spread from person to person and is not considered contagious.
Over the years, there have been many outbreaks that were usually contained. Most recently, in 2020, Siberia, Russia experienced a major anthrax outbreak that affected at least 13 Siberian people and killed more than 2,000 deer. Authorities believe thawing permafrost exposed the deer that died of anthrax 75 years ago, causing the release of anthrax spores.
What causes anthrax?
The causative agent of anthrax is a bacterium called Bacillus anthracis. While other researchers discovered the anthrax bacilli, a pure culture was obtained by German physician and scientist Dr. Robert Koch, who proved that the anthrax bacterium was the cause of the disease that affected farm animals in his community. Under a microscope, bacteria look like large rods. However, in the soil where they live, Siberian organisms exist in an inactive form called spores. These spores are very hardy and difficult to destroy. The spores are known to survive in soil for 48 years. Bacteria produce toxins made up of three proteins called:
- Protective antigen (protective factor);
- Inflammatory factor (edematous factor);
- Lethal factor (death factor).
How is anthrax transmitted?
Anthrax can infect people in three ways. The most common infection is through the skin. People and animals can get anthrax by eating the carcasses of dead animals that have been infected with anthrax. Ingesting anthrax can cause serious, sometimes fatal illness. The deadliest form is inhalation anthrax. If anthrax spores are inhaled, they migrate to the lymph nodes in the chest, where they multiply, spread, and produce toxins that often cause death.
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Etiological factors of the disease
The causative agent of anthrax is Bacillus anthracis. According to their shape, anthrax bacteria are rods (non-motile and gram-positive).
It should be noted that toxin-forming (vegetative bacillus) forms of the pathogen are extremely unstable in the environment. They quickly collapse under unfavorable conditions (heating above eighty degrees, boiling, treatment with disinfectant solutions, etc.).
In this regard, the causative agent of SA is capable of forming spores that are resistant to adverse factors.
How common is anthrax? What are the risk factors for getting anthrax?
Anthrax in people in developed countries is now rare. But the disease still exists today, mainly in countries that do not have public health regulations that prevent infection of goats, cattle, sheep and horses and their products. In the past few years, cases of anthrax have been reported in people exposed to imported animal skins used to make drums. Drummers and their families were infected in this way. Individuals who are at higher risk of contracting anthrax include:
- Veterinarians;
- Livestock breeders and farmers;
- Travelers to areas where anthrax is endemic;
- Processors of animal products (eg animal skins);
- Laboratory personnel studying anthrax;
What types of anthrax are there? What are the signs and symptoms of anthrax infections?
There are four forms of disease caused by anthrax:
- Cutaneous anthrax.
- Inhalation anthrax.
- Gastrointestinal anthrax.
- Injection anthrax.
Cutaneous anthrax
Cutaneous anthrax (80% of all anthrax infections) begins as a red-brown raised patch that enlarges with significant redness around it, blistering and hardening. Then an ulcerative crater appears in the center of the spot with blood drainage and the formation of a black crust. There are swollen glands (lymph nodes) in the area. Symptoms include:
- Muscle pain;
- Headache;
- Increased body temperature
- Nausea and vomiting.
The illness usually resolves in about six weeks, but deaths can occur if patients do not receive appropriate antibiotics.
Injection anthrax
This new form of anthrax has been identified in injecting drug users in Northern Europe. Symptoms may take anywhere from a few days to several months to appear. Signs and symptoms of injection anthrax may include small blisters or bumps that may itch at the injection site, fever and chills, swelling around the sores, and deep abscesses may develop under the skin or muscle. Painless skin ulcers with black centers (dark scabs) may appear after blisters or bumps develop.
Inhalational anthrax
The first symptoms are subtle, gradual and flu-like (flu) symptoms with a sore throat and headaches. However, after a few days the illness worsens and there may be severe respiratory distress with shortness of breath and chest and/or muscle pain. Some patients may begin to cough up blood. Shock, coma and death follow these symptoms. Inhalation anthrax does not cause true pneumonia. In fact, the spores are carried into the lungs by cells called macrophages. Most spores are dead. Unfortunately, some survive and are carried to glands in the breasts called lymph nodes.
Lymph nodes may increase in size. In the lymph nodes, spores that survive multiply, produce deadly toxins, and spread throughout the body. Severe bleeding and tissue death (necrosis) occurs in these lymph nodes. From there, the disease spreads to the adjacent lungs and the rest of the body. Inhalation anthrax is a very serious disease and, unfortunately, most affected people will die from the disease, even if they receive appropriate antibiotics. Why is this so? Antibiotics are effective in killing bacteria, but they do not destroy the deadly toxins that have already been released by the anthrax bacteria.
Gastrointestinal anthrax
The now rare intestinal anthrax (gastrointestinal anthrax) results from eating undercooked contaminated meat. Symptoms of this form of anthrax include nausea, loss of appetite, bloody diarrhea and fever followed by abdominal pain. Bacteria penetrate the intestinal wall. The infection then spreads throughout the body through the bloodstream (sepsis) with fatal toxicity.
How the disease develops
The incubation period for anthrax ranges from several hours to 8 – 14 days.
Contact route of infection
After the incubation period, anthrax carbuncle begins to develop on open areas of the skin of the extremities and head, affecting the deep layers of the skin. The inflammation is hemorrhagic-necrotic in nature. Tissue swelling develops quickly. Tissue destruction occurs from the center to the periphery, where a black-brown crust appears. Macrophages carry bacteria to regional lymph nodes, which prevent further spread of infection.
Alimentary route of infection
With the alimentary route of infection, pathogens enter the gastrointestinal tract with infected products. In case of damage to the mucous membrane, pathogen spores with macrophages are transferred to the mesenteric lymph nodes. The primary anthrax lesion does not develop. Lymph nodes prevent further spread of infection. With massive damage to the mesenteric lymph nodes, necrotic inflammation can develop. Pathogenic bacteria break into the blood. Bacterial sepsis develops.
Airborne dust route of infection
During the airborne dust route of infection, spores of the anthrax pathogen enter the mucous membrane of the respiratory tract. Next, macrophages transport them to regional lymph nodes, which prevent further spread of infection. However, with massive damage, necrotic inflammation of the lymph nodes may develop. Pathogenic bacteria break into the blood. Bacterial sepsis and anthrax pneumonia develop.
Rice. 8. Anthrax carbuncle on the face. Severe soft tissue swelling.
Rice. 9. Anthrax carbuncle on the face. Severe soft tissue swelling.
How is anthrax diagnosed?
History is important, including human occupation. The bacteria can be found in cultures or swabs in cutaneous anthrax and in throat swabs and sputum in pulmonary anthrax. A chest x-ray may also show characteristic changes in and between the lungs. Once anthrax has spread, the bacteria can be seen in the blood using a microscope. Of course, if anthrax is deliberately spread, the manifestations of the disease may be unusual. Indeed, as a result of the 2001 bioterrorism attack in the United States, anthrax spores were distributed through the postal system in the form of a white powder sent by letters.
Risk areas and precautions
Herbivores
During periods of increased danger and beyond, it is necessary to be very careful when contacting large and small cattle, horses, camels and pigs and not allow children to play with these animals.
Flies, horseflies
Protect windows and entrance doors with screens. Immediately destroy these insects if they enter living quarters and kitchens, especially in houses outside the city, in close proximity to livestock.
Contaminated animal feed
Do not buy animal feed from unverified manufacturers, beware of buying cut grass and hay from random sellers, this grass could have been cut in disadvantaged areas.
Corpses of infected animals
Never visit burial sites of sick animals, try to avoid any routes that pass through these places.
The soil in which the corpse of a dead animal was buried
Contaminated soil remains infectious for decades. Never buy land or settle near such areas, even if soil surface tests have not revealed any hazards. The main accumulations of anthrax spores in cattle burial grounds are deep underground, and any construction or excavation work, as well as storm and flood waters, can easily bring a deadly infection to the surface at any time that can infect animals and people.
Contaminated animal raw materials
Great care should be taken when purchasing skins, any fur and leather products of small handicraft production. Do not buy such goods at spontaneous markets and highways; ask private sellers for a license.
Meat from infected animals
Buy any meat products only in special pavilions, in compliance with all sanitary standards and measures. Never purchase raw meat and meat products from dubious sellers who spontaneously sell meat in markets, in the courtyards of private houses, or directly from open trunks of cars on the highways.
What is the treatment for anthrax?
In most cases, early treatment can cure anthrax. Cutaneous anthrax can be treated with common antibiotics such as penicillin, tetracycline, erythromycin, and ciprofloxacin.
Inhalational anthrax is a medical emergency. Early and continuous intravenous antibiotic therapy can be life-saving. A vaccine exists, but is not yet available to the general public. Most experts believe that the vaccine will also be given to people who have suffered a bioterrorism attack. It should be noted that anthrax is a reportable disease. This means that local or state health facilities must be notified if a case of anthrax is diagnosed. These institutions can better characterize anthrax so that the affected person can receive the most effective treatment for that particular organism.
Persons exposed to aerosolized spores can participate in the prevention of post-traumatic anthrax exposure. The FDA recommends four antibiotics: doxycycline, ciprofloxacin, levofloxacin, and parenteral procaine penicillin G. In addition to these antibiotics, a three-dose series of Siberian vaccine should be given as soon as possible after exposure.
Can anthrax be prevented?
Public health measures to prevent exposure to infected animals are invaluable. There is a vaccine for high-risk people (for example, veterinarians, laboratory technicians, employees of textile factories that process imported goat hair, and military personnel). Vaccines are being developed for anthrax and other infectious diseases that are more effective and have fewer side effects. Currently, most vaccines are given by injection into subcutaneous fat or muscle. Early studies in experimental animals show effectiveness for an oral anthrax vaccine. Obviously, a pill is easier to take than a shot, and a pill may be an even safer and more effective method of administration.
Literature
- Burgasov P. N., Zinoviev A. S., Nikiforov V. N., Shlyakhov E. N. Anthrax
// Great Medical Encyclopedia, 3rd ed. - M.: Soviet Encyclopedia. - T. 23. - Cherkassky B. L., Lavrova M. Ya.
Anthrax of wild animals and the problem of natural focality of this infection // Bulletin of Moscow. islands of nature explorers. Dept. biol.. - M.: Moscow University Publishing House, 1969. - T. 74, issue. 5. - pp. 5-19. - Burgasov P.N. et al.
Anthrax. - M.: Medicine, 1970. - 128 p. — 5000 copies. (region) - Cherkassky B. L.
Epidemiology and prevention of anthrax: monograph = Epidemiology and Prevention of Anthrax: (Russian experience) / Review: N. N. Filatov. - M.: Intersen, 2002. - 384 p. — ISBN 5-89834-077-7. (in translation) - Anthrax: current problems in the development and implementation of medical protective equipment: A guide for doctors: (To the 80th anniversary of the Federal State Institution “48 Central Research Institute of the Ministry of Defense of Russia”) / Ed. G. G. Onishchenko, V. V. Kozhukhova; Reviewers: D.K. Lvov, V.N. Pautov. - M.: Medicine, 2010. - 424 p. — 530 copies. — ISBN 5-225-03411-X. (in translation)
- GOST 15991-86 “STI live vaccine against anthrax in animals. Technical conditions".
- GOST R 52616-2006 “Vaccine against animal anthrax from strain 55-VNIIVViM live. Technical conditions".
