Anthrax is an infectious disease caused by bacteria: Bacillus antracis. This bacterium is characterized by a rod shape (bacillus) and is of the Gram + type. This Gram stain enables bacteria to be classified according to their morphological characteristics. (2)

The mode of contamination is by infected animal or by ingestion of contaminated animal products. Humans can be exposed to the bacteria by handling or stroking animals or even when working the skin to shape leather.

There are three well-defined modes of contamination:

– skin infection (by transfer through the skin);

– inhalation (pulmonary contamination);

– ingestion (gastrointestinal contamination).

Contamination through skin contact remains the most common mode of transmission. Nevertheless, the inhalation of spores (vegetative propagation organs) remains a significant form of contamination. (3)

This disease is present all over the world and affects both domestic and wild animals. The animal populations most affected are: cattle, sheep, goats, camels and antelopes. (3)

Most cases of Anthrax are sporadic cases (which only affects certain individuals in a population, unexpectedly). In addition, outbreaks of contaminated animals may be visible in France, but generally do not exceed the order of ten. (1)

Anthrax came to the public eye following the significant events of 2011 relating to the use of Bacillus antracis in bioterrorism. (1)

Anthrax is defined in three forms: cutaneous form, gastrointestinal form and pulmonary form. In this sense, the associated symptoms depend on the type of infection. These can appear anywhere on the body and can range from a day to over 2 months.

In the context where the disease is not diagnosed as quickly as possible or it is not treated, the clinical manifestations can spread over the whole body and cause severe consequences that can lead to lethality. from subject. (3)

• the cutaneous form is characterized by the entry of spores (vegetative propagation organs) at the level of a lesion of the skin. This type of disease corresponds to 95% of anthrax cases. The associated clinical manifestations are first of all similar to an insect bite. These then progress to the formation of an ulcer of size between 1 and 3 cm in diameter. This ulcer is followed by necrosis and may progress to the development of sepsis. This form of the disease is fatal in 20% of cases if effective treatment is not implemented quickly;
• the gastrointestinal form is defined as the result of ingestion by a person of contaminated food. Transmission of the bacteria to humans occurs by animal, the food concerned is essentially meat. The symptoms associated with this form of the disease are gastrointestinal in nature. This is an acute inflammation of the digestive tract. The patient with this form of Anthrax presents with nausea, loss of appetite, vomiting, fevers, abdominal pain and severe diarrhea. The mortality associated with this pathological type ranges from 25 to 60%;
• the pulmonary form results in the inhalation of spores (multiplication organs) in the air. The primary symptoms of this form are similar to a cold. However, complications appear quickly (in a few days) and correspond to severe respiratory disorders, severe headaches, muscle pain that can lead to septic shock (presence of bacterial toxins in the blood leading to circulatory disorders and impacting the cardiovascular system). In the absence of therapeutic management, this form is lethal for almost all affected subjects.

Anthrax disease most commonly affects ungulate animals, such as sheep, goats or cattle.

People who come into direct contact (skin contact) or indirect (ingestion of contaminated meat) with infected animals can develop the disease.

 The source of contamination is therefore the animal and transmission can take place through 3 modes:

• cutaneous;
• pulmonary;
• gastro-intestinal.

Skin infection results in the adhesion of the sporadic form of the bacteria through the skin in the presence of a cut, scratch, scar, etc. It is the most common mode of bacterial transmission in Anthrax disease. The major risks of becoming contaminated with the bacteria are contact with the skin, hair or bones of animals. In this sense, the people most at risk of developing the pathology are those in close contact with animals: farmers, veterinarians, tanners and people working with wool.

Transmission by inhalation is the result of the presence of bacterial spores in the air. These vegetative forms therefore do not enter the upper respiratory tract of the individual and reach the lungs. The most probable situations when inhaling bacterial spores correspond to the tanning process of animal skin or during the treatment of wool.

Furthermore, inhaling spores by an individual does not necessarily mean that they will develop the associated symptoms. This is because the germination time of the spores ranges from 1 to 6 days and the symptoms of this form of the disease do not develop until the final stage of germination. In this sense, if the spores are ejected from the body before germination is complete, symptoms will not develop. Once the spores have germinated, they release many toxic substances that can cause internal bleeding, edema or even destroy certain tissues.

Finally, gastrointestinal transmission is effective following ingestion of an infected animal.

Another cause associated with Anthrax is the use of Bacillus antracis as a biological weapon and in bioterrorism.

The risk factors for developing Anthrax are due to close contact with infected animals (sheep, cattle, ungulates, etc.).

The disease is characterized in three forms: cutaneous, pulmonary, gastrointestinal, it turns out that the risk factors are linked to direct contact with animals. But also during the ingestion of contaminated meat or during the inhalation of the sporulated form of the bacterium present in the ambient air.

The diagnosis of Anthrax depends on the form of contamination.

In the event of a suspected infection with Bacillus antracis by inhalation, an x-ray of the lungs is often taken. A lung scan can complete the x-ray examination to confirm or not the diagnosis. Significant radiological manifestations of infection by inhalation are: (2)

– enlargement of the mediastinum: region of the thoracic cage located between the two lungs and containing the heart, the esophagus, the trachea and the stem bronchi;

– pleural effusion, i.e. the presence of fluid in the pleural cavity (membrane covering the lungs).

Added to medical imaging examinations, other means make it possible to make the possible diagnosis of the disease, these are in particular: (2)

– biological tests to measure the level of antibodies or the level of toxins present in the blood;

– analysis of blood samples, damaged and infected skin, respiratory secretions, etc.

The usual treatment for Anthrax is based on antibiotic therapy: penicillin, doxycycline, ciprofloxacin.

However, the pulmonary form of the disease can also be treated with antibiotics combined with other drugs. These are usually administered intravenously. The treatment of the disease is often effective in the long term as a result of the germination of the spores which can be more or less long. (4)

Prevention relating to this pathology involves avoiding contact with potentially contaminated animals. It is, in particular, strongly advised to eliminate the charcoal animals by incineration or by burial. In addition, the vaccination of animals at risk is an effective preventive means to avoid contamination.

Prophylactic measures (medical means) are also available to prevent disease.

It is remarkable that vaccines intended for animals are much more effective than those intended for humans. (1)