In history, this disease is known as the "sacred fire", "Persian fire" and other similar associations. The anthrax got its modern name because of its distribution area. Today, human infections are casuistic. The disease is found only in cattle. The causative agent is described in the late nineteenth century by Robert Koch.
Pathogen
The bacterium Bacillus anthracis causes anthrax. This is a large stick, painted according to Gram in purple. It contains a somatic antigen, and also releases a toxin that provokes edema, interacts with the membranes of the body’s cells and causes death. In addition, the capsule exhibits antifagocytic properties.
Outside the host organism, bacteria form spores that are resistant to heat, drying and disinfection. In this form, anthrax can be stored for years, and also used as a bacterial weapon. Vegetative forms of microorganisms die from exposure to hot water after forty minutes, in a dry oven - after 2-3 hours.
Epidemiology
The carrier of infection are herbivores. As a rule, these are cows, horses, camels or pigs. Infections for humans persist throughout the course of livestock disease, as it releases the pathogen into the environment. And the corpses of animals remain infectious for a week. In addition, the transmission of the pathogen is realized through blood-sucking insects. Of particular danger are products obtained from sick animals (skin, wool). They can remain contagious for many years, even after chemical and heat treatment.
Geographically, anthrax is found in countries with a hot, humid climate, in areas where cattle are bred. The disease is usually recorded in the summer-autumn period. The main cause of human infection is the neglect of sanitary and epidemiological standards, as well as insufficient processing of materials before processing them.
Pathogenesis and symptoms
Bacteria enter the human or animal body through the skin, mucous membranes, or gastric tract. In the "gates of infection" serous hemorrhagic inflammation develops, which is manifested by edema, bleeding and dry necrosis. This place looks like a smoldering charcoal - a black area bordered by an inflammatory shaft, in the center of which there is an open wound. Macrophages carry the pathogen through the lymphatic system, including regional lymph nodes. After bacteria enter the bloodstream, secondary sepsis develops with generalization of the infection throughout the body: in the lymph nodes, the gastrointestinal tract, and the lungs. Multiple hemorrhages and bleeding appear in the target organs.
The incubation period of the infection can last from several hours to two weeks, depending on the form. Most often, skin manifestations of the disease can be found. At the site of penetration of the pathogen, red papules appear, a feeling of itching and burning. A day later, the papule evolves into a vesicle filled with serous fluid. After a short time, the content acquires a crimson or dark purple hue. Due to severe itching, a person damages the dome of the vesicle and an ulcer appears with a dark bottom and a bright outline. Bacterial screenings (“necklace symptom”) are formed along its edges, which go through the same stages.
After a couple of weeks, the bottom of the ulcer closes with a black scab, and a local anesthetic reaction appears for the entire period of the disease. This is one of the diagnostic signs of anthrax. Of the common symptoms, a long fever is distinguished, accompanied by headache, adynamia and muscle pain. After two to three weeks, local manifestations disappear, and with them the general intoxication symptom.
Diagnostics
The most common skin form of the disease is differentiated with other bacterial boils and carbuncles. The main distinguishing feature is the appearance of a “necklace”, which is characteristic only for anthrax. The generalized form is characterized by a rapid onset, severe intoxication, pulmonary edema, oligo- and anuria. Sometimes, if there is a source of the disease, the doctor needs to distinguish anthrax from tularemia and plague.
From laboratory studies to diagnose the disease, you can use bacterioscopy of blood or urine, as well as sowing the discharge from the wound on nutrient media. In addition, laboratory animals can be used to make a more accurate diagnosis. Serological reactions will help determine the phase of the disease and the readiness of the immune system. Another method is allergy testing with anthraxin.
Anthrax vaccine
For the prevention of anthrax, a live, dry vaccine has been developed that is suitable for subcutaneous or cutaneous use. It is produced in ampoules of 1 ml (calculated for 200 doses of subcutaneous injection) complete with 1.5 ml of solvent (glycerol solution).
Anthrax vaccine for humans is a mixture of live spores of the pathogen and purified antigens attached to aluminum hydroxide. The doctor adds isotonic saline to the ampoule, turning the powder into a homogeneous mixture. Shelf life of dry vaccine is 3 years, and liquid - 2.
For adults and children from 1 year old, any anthrax vaccine can be used. The instruction accompanying it states that a person develops a tense immunity.
Contraindications to vaccination
There are general rules for administering all vaccines:
- the patient must be healthy;
- body temperature in the normal range;
- after the last ARVI more than a month has passed;
- no allergic reactions to previous vaccine administration were observed.
Instructions for the use of the vaccine against anthrax emit a few more contraindications. So, a person should not have a history of systemic diseases of the connective tissue, recurrent dermatological pathologies, as well as problems with the endocrine system. In addition, you need to adhere to time intervals. Between the last vaccination and immunization against anthrax there should be a gap of at least thirty days.
Vaccine Reactions
The use of anthrax vaccine causes local and general reactions. With subcutaneous administration after a day, a section of hyperemia and a slight swelling of the tissues appear on the skin at the injection site. Later, a crust forms there, which eventually disappears. Subcutaneous administration of the vaccine is accompanied by the appearance of infiltrate up to 0.5 cm in size.
General malaise develops extremely rarely and manifests itself in a headache, fever to subfebrile numbers, as well as an increase in lymph nodes. Nausea and vomiting are sometimes possible. In people with an increased immune response, the anthrax vaccine can cause an allergic reaction up to anaphylactic shock.
Dosage and administration
For the first time, vaccination is carried out with a dry and liquid vaccine, and subsequently only the dry version is used. Scheduled in the first quarter of the year, the susceptible contingent receives a dose of medication in a volume of up to 0.5 ml subcutaneously.
There are two methods for administering a dry anthrax vaccine for humans. The instruction states that children from 14 years old need to undergo primary immunization subcutaneously with two doses with a break of a month. For adults, 2 drops of the diluted vaccine are applied to the outer middle third of the shoulder, and then they scratch the skin and rub in the liquid for half a minute.
In case of contact of an unvaccinated person with a sick animal, he is given emergency prophylaxis in the form of a course of antibiotics:
- for adults, it is Ciprofloxacin or Doxycycline;
- for children - Amoxicillin.
Anthrax vaccines for animals
The anthrax vaccine causes the animal to produce antibodies to the pathogen within 10 days from the time of administration and provides stable immunity for up to one year. It is intended for routine compulsory immunization of all livestock.
The first time vaccinations are given at the age of one month, and then again after six months. Adults should be vaccinated every year. If an animal was found in the livestock with signs of anthrax, then the whole herd is vaccinated again.
Contraindications to vaccination of animals:
- fever;
- pregnancy or recent castration;
- surgical operations;
- foals up to 9 months old.
The anthrax vaccine is not administered in the hot or cold season, or in combination with other medicines. With treatment with antibiotics, anthelmintic and insectoacaricidal drugs, it is necessary to wait at least 10 days from the moment of vaccination. The vaccinated cows are allowed to drink milk the very next day after vaccination, but slaughter of cattle for meat will have to be postponed for two weeks.