Anthrax is an acute infectious disease of the zoonosis group and is the primary disease of numerous species of herbivores, but can also be transmitted to humans under certain conditions.
Anthrax in humans causes severe acute infectious disease, which is often accompanied by intoxication and the creation of a specific skin change. black pus or malignant pustule.
The skin form of the disease predominates in 95-99% of cases, with a smaller proportion presenting the intestinal and lung, which are severe forms of the disease. The most rare is primary anthrax sepsis, which is followed by high mortality.
Anthrax is caused by Bacillus anthracis, which is encapsulated in the tissues and organs of infected animals and humans and survives in the form of spores in the external environment. Spores are highly resistant to various physical and chemical factors and other external influences and can survive for decades in the outside environment.
Epizootology and Epidemiology
The primary source of infection in infected animals is their excretions – faeces, urine, milk, but also carcasses of animals killed by anthrax that are not handled and buried under regulations; then flesh from the slaughtered animals and various organs and tissues that serve as raw materials, such as skin, fibers, bones and blood.
Secondary sources of contamination are contaminated food, water and soil with anthrax bacilli. Spores from the soil contaminate hay and grass. Large livestock are infected on pastures where there are anthrax spores that can survive in soil for favorable conditions after several decades.
People can get anthrax if they come in contact with infected or dead animals or contaminated animal products, including carcasses, skin, wool, meat, bone meal, which are the source of the infection. The disease is most often associated with the slaughter, slaughter and burial of anthrax animals, as well as the use of meat or other animal products from compulsively slaughtered or dead anthrax animals for food.
The most important ways of transmitting anthrax from animal to human are:
- Direct contact with the diseased animal – its tissues and organs and its products, which is the most common route of transmission;
- Alimentary (intestinal) pathway – occurs due to the consumption of raw or insufficiently heat-treated meat or milk from animals infected or killed by anthrax, and
- Respiratory tract – by inhalation of anthrax spores (when slaughtering, slaughtering, working with leather or wool from diseased or dying of anthrax animals, or in laboratory conditions).
The cause of infection in the human body usually enters through the skin and mucous membranes. Skin and inhalation anthrax most commonly occur in laboratory workers.
Although excretions from skin changes in humans are potentially contagious, human-to-human transmission of the disease does not occur practically, making anthrax considered a non-contagious disease.
But because of the stability and durability of outdoor spores, the ability to disperse them in the air, and the high rate of inhalation anthrax mortality, anthrax bacilli can be used as biological weapons.
The incubation period for all forms of anthrax is generally less than 2 weeks. Symptoms of the disease vary depending on how the infection occurs, but usually occur within the first 7 days after exposure (usually the first 48 hours).
Human anthrax occurs in three clinical forms:
The skin form is the most common form of manifestation of the disease. It begins with the appearance of a single or group of small blisters (vesicles) that are usually itchy, at the point where the anthrax bacillus enters. Skin changes spread and ulcerate in the center for a day or two, giving the characteristic appearance of the lesion: black central, reddish around and pale yellow wider area of the wound. Swelling can occur around the sore spot, and the wound itself is painless. Most often such changes are localized on the skin of the face, neck, hands or hands. The regional lymph nodes are swollen and may have accompanying symptoms such as fever, fatigue and headache.
In most cases the disease ends at this stage – the wound heals, and remains a mark on the spot.
Rarely, the disease can get a harder clinical course, with the general condition worsening, although with appropriate antibiotic therapy the prognosis is good.
In a small number of cases the disease progresses to septic anthrax, which is an extremely severe form, with high mortality.
The pulmonary form of anthrax occurs less frequently and may initially resemble a common cold. It occurs after inhalation of anthrax spores and is characterized by high fever, chest pain, difficulty breathing, cough, headache and body aches, fatigue, nausea, vomiting, dizziness. After a few days the symptoms progress to severe general intoxication, confusion, respiratory insufficiency and shock. The disease usually manifests as bronchopneumonia and hemorrhagic pleurisy. This form is one of the most severe manifestations of anthrax disease and if antibiotic therapy is not applied on time, the disease always ends in death.
The intestinal form of anthrax is a rare disease that begins acutely and severe intoxication occurs in the first hours of illness – fever increases, general malaise, headache, fainting, abdominal pain, nausea, vomiting often with blood, and less frequently diarrhea. The patient has the appearance of being severely ill, and often, despite adequate treatment, death occurs.
The diagnosis of cutaneous anthrax is confirmed by the finding of anthrax bacilli in direct splitting of material taken from the skin change.
The laboratory finding of anthrax bacilli in appropriate clinical material (blood, liquor, respiratory secretion) that has been previously cultured or directly microscopically confirms the diagnosis of other forms of anthrax.
Diagnosis of anthrax with human antigen or antibody testing is also performed using other methods – polymerase chain reaction (PCR), as well as immunohistochemical tests, immunofluorescence reactions, and enzyme assay and essay levels of immunoglobulins.
The test material should be taken prior to initiating antibiotic therapy.
Treating anthrax sufferers with antibiotics is essential and any delay in treatment reduces the chances of survival. The drug of choice is penicillin, but doxycycline as well as fluoroquinolones are given.
Prevention and suppression
Anti-epizootiological measures include the detection of infected animals and their proper, controlled destruction and safe disposal (incineration, burying).
To protect the soil from contamination with anthrax spores, burying dead animals without a diagnosis should be prohibited. Animal carcasses should be cremated or buried at a depth of 2 meters after prior disinfection.
It is mandatory to disinfect, wash and sterilize wool, skin and bone meal used as raw materials in industry.
There is an anthrax vaccine and its application is an important preventive measure for the immunization of animals.
According to the recommendations of the veterinary services, in areas where anthrax is present in the animals, vaccination is carried out in the fall every year for the next twenty years.
Preventive measures to prevent infection in humans, especially those who are professionally exposed, include the use of protective clothing and equipment: suits, cloaks, boots, gloves, masks, sunglasses, etc. safeguards in the process of work.
In laboratories handling anthrax-susceptible infectious material, it is necessary to abide by all standard operating procedures for the protection of personnel required by practice, that is, material handling at the biosecurity level 3.
Meat and other animal products from diseased and coerced animals must not be used in the diet.
Thorough and proper heat treatment of food of animal origin is required to be safe to use.
Persons exposed to immediate danger and possible inhalation of anthrax bacilli / spores (laboratory workers, other occupationally exposed persons), after individual evaluation, undergo preventive chemoprophylaxis by administering antimicrobials – ciprofloxacin or doxycycline.
There is a licensed human anthrax vaccine for human use, but immunization of people against anthrax is not recommended unless there is a risk of repeated exposure to anthrax spores.
Anthrax is a disease that is widespread worldwide. In Europe today, it is a rare disease, while major outbreaks are still registered in some countries in Africa and Asia.
Situation in North Macedonia
In North Macedonia, for the last 30 years anthrax has been recorded with not very high numbers of clinically confirmed cases of cutaneous anthrax – double digits up to 1991, with the highest number reported in 1988 (30 in total).
Since 1992, the number of registered anthrax patients annually has been one-digit, and in 2004 there is no anthrax in Macedonia for the first time (Table 1).
From 2005 until the end of 2018, only 15 cases of anthrax have been registered in six separate years (the highest number 4, in 2005) (Table 2).
In 2019 there was no registered case of anthrax in humans in Macedonia.
|Number of patients||9||9||9||5||5||9||3||3||8||6||1||2||0|
|Number of patients||4||0||3||2||0||0||3||2||0||1||0||0||0||0|