Coal (disease)

History

The bacterium of coal was identified by the German Aloys Pollender in 1849 and by the French Rayer and Davaine in 1850. In 1863, Davaine made of it a thorough study, considered now as the first proof of the microbial origin of one communicable disease to the man. In 1876, Robert Koch discovered the capacity of the bacterium of coal to form spores, which can make it very resistant.

In May 1881, with Pouilly-Le-Fort, close to Melun, Pasteur carries out a great experiment of vaccination on 50 sheep. It prepares two batches of 25. The first batch receives, at 15 days of interval, two injections of anti-carbonaceous vaccine prepared by Louis Pasteur and his collaborators. Then the two batches receive an injection of alive culture of carbonaceous bacillus. All the not vaccinated animals die. All vaccinated survive. Pasteur, who is not Médecin but Chimiste, is from now on famous.

It seems well established that, as opposed to what Pasteur made it clear, the vaccine used with Pouilly-le-Fort had been attenuated with the assistance not of oxygen but of a disinfectant, the potassium bichromate. See on top, and in particular to the measure in which one can reproach Pasteur for being oneself suitable an idea of Henry All Saints' day, the article Secret of Pouilly-le-Fort

Description of the germ

Bacillus anthracis is a bacterium with positive Gram; the Bacille is motionless (does not have a Flagelle), which distinguishes it from the others Bacilli which are mobile; the bacterium is Sporulant E and its respiratory type is Aérobie/optional Anaérobie. The Spore S of the bacillus of coal are highly resistant. They germinent in the vegetative shape when they are in environments such as the Sang or the fabrics, of the Men or the animals; rich person in amino-acid, Nucleotide S and Glucose. In spite of their high strength, the spores do not reproduce, on the other hand they can survive of tens of years in the ground. There exists a problem of destruction of Bacillus anthracis from the resistance of the spores to the Sécheresse, heat, the rays Ultra-violet S, the gamma rays and with many substances Disinfecting be. Bacillus anthracis has two factors of virulence:

First of all the capsule enables him to escape the Phagocytose.
Ensuite there exist two Toxine S made up of three Protéine S distinct (the protective Antigène, the factor œdematogene and the lethal factor). When the first two proteins are associated, they form the Toxine œdematogene while when the protective Antigène is associated with the lethal factor there is formation of lethal toxin. The latter acts directly on the virulence of the Bactérie, if it undergoes a deficiency, virulence will be reduced of a factor by 1.000.

Human pathology

At the Man, coal generally appears by its cutaneous form: the malignant Pustule. This one begin with a small red and pruriginous spot, then appears a blister and a Phlyctène (bulb) which breaks and forms a Escarre noirâtre from where the name of the disease.

The inhalation of the infectious agent causes pulmonary coal extremely serious which can become complicated carbonaceous Septicémie.

The Antibiotic S adapted managed early, in sufficient amounts and sufficiently a long time have an unquestionable effectiveness.

Ways of contamination and effects on the organization

There exist various kinds of contamination of Bacillus anthracis generating various degrees of consequences on the organization. The infection at the human ones occurs by spores usually coming from animals or products from contaminated animals but also during a voluntary propagation. There exist the three shapes of contamination of coal:

cutaneous coal.
gastro-intestinal coal.
coal by inhalation.

These three forms have various consequences on the organization.

The cutaneous form

This contamination represents the most frequent form. This infection results from a contact between the spores and a wound. This coal shape accounts for 95% of the infections due to the Bacillus anthracis .

This infection causes the formation of a Macule at the place of the inoculation and causes itchings. One day after, it is transformed into Ulcération surrounded by blisters. The button is painless and inserted, it desiccates and covers then black crust. In 80% of the cases, the wound cures without complication, despite everything, in certain cases the edema intensifies and takes volume generating a deformation of the face. Initially strong a Fièvre appears which without treatment involves strong complications. These complications evolve to death in 5% to 20% of the cases.

The gastro-intestinal form

This infection results from the meat consumption containing of the endospores, an infection due to Bacillus anthracis by gastro-intestinal way is however not very widespread.

Gastro-intestinal coal appears if spores are found in the higher or lower gastro-intestinal ways. In the first case, the form oropharyngienne is characterized by the appearance of an ulcer œsophagien or oral examination with a regional Adénopathie lymphatic and a Septicémie. Whenever the Spore S are presented in the lower gastro-intestinal ways, the nausea S and Vomissement S are quickly followed of Diarrhée S sanguinolentes, of a perforation of the Intestin S and Septicémie S; a massive Ascite can appear. The death rate of this form variable but is raised and can reach 100%.

The respiratory form

This coal shape comes from the inhalation of Spore S via particles or a contaminated aerosol. The inhalation of spores is followed of a not very specific syndrome grippal accompanied by Fièvre, muscular pains, and headaches dry Toux.

The spores settle in the air cells. The Macrophage S which phagocytent them burst and the released spores are transported by the lymphatic Système with the ganglia tracheobronchic. The spores give birth has vegetative forms which multiply and which produce Toxine S up to sixty days later.

Two to four days after the beginning of the symptoms, it appears a sudden aggravation of the general situation. One observes a respiratory insufficiency serious, acute pains rétrosternales and a Hypotension. A hemorrhagic Méningite can be an additional complication being added to the syndromes.

Sometimes the patient dies a few hours after the beginning of this second phase. To this moment, a Radiographie of the thorax presents a typical image of dilation médiastinale characteristic of the hemorrhagic lymphodenopathy médiastinale and the médiastinite. This form accounts certainly for only 5% of the cases of coal but its death rate is estimated between 90 and 100%.

Propagation of coal

The coal shape per inhalation being more the mortal, the malevolent propagation of Bacillus anthracis can be dangerous when great quantities of spores are dispersed in an aerosol. This threat must be taken with serious because the organization can relatively easily be manufactured starting from natural sources.

It is not however obvious to manufacture an infectious coal aerosol. Indeed, the dispersed particles must be of a size ranging between 1 and 5 Micromètre S and one needs a sufficient quantity of energy to allow a dispersion in the Air.

Moreover the infectious amount 50 for the inhalation of coal is estimated at 10 000 spores. It is the amount of spores necessary so that 50% of the exposed people develop the Maladie.

The greatest risk for the Man is at the moment when the spores of coal are released in the Air and all the time where they remain in the air. Once the spores with ground, the risk of contamination is much less great. The dispersion of the spores must thus take into account the weather factors and the characteristics of the aerosol.

Transmission of Bacillus anthracis

The transmission can be done only at the time of contact with skins of infected animals or animals themselves. Indeed the transmission of man with man was not proven. The patients do not constitute any danger, it is thus not necessary to isolate them.

Treatments

The infection of Bacillus anthracis can be destroyed by a treatment. This one must be precise and started as of the appearance of the symptoms. There exists a vaccine, which is recommended to the personnel of laboratory frequently exposed to the clinical samples and the cultures.

There exist different Médicament S to use at the time of a Infection with Bacillus anthracis . Those vary according to the age of the patient and the degree of the Maladie. The principal drugs are:

the Ciprofloxacine
the Ofloxacine
the vafloxacine
the Doxycycline
the Amoxicilline
the Péfloxacine.

The terrorist risk

The events with the the United States at the end of 2001 showed us that Bacillus anthracis was one of the germs which could constitute a major biological terrorist threat.

Stocks (of various virulences) are held in the official collections such as that of the Pasteur Institute of Paris. “Wild” stocks exits of the contaminated cattle are more than extremely rare in France. The last two French episodes on the livestock date from the years 1990 (Haute-Savoie and the Pyrenees Atlantiques). The bacteriological culture requires basic culture media but of great precautions as for the risk of contamination of the operator and is not possible that in specialized laboratories P3 type. He is kamikaze to want and succeed in cultivating B.a. on a corner of his kitchen table. All the stocks of B.a. do not have the same pathogenic capacity and often lose it at the time of multiple road repairs. The dissemination of the spores is variable, weak in general, and the military stocks are especially treated surfaces some in order to increase this capacity of dissemination. The threat exists but it can be only specific, intended to frighten the populations and/or to kill a restricted number people after a time of incubation which then makes very difficult the localization of the place of dissemination and counting.

Obligatory declaration

In France and Belgium, this disease is on the list of the Infectious illness to obligatory declaration.

References

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