Lecture on anthrax

2021-03-24 12:00 AM

People become infected in cases of abrasions on the skin due to contact with the wastes of sick animals or the slaughter of animals that have died from anthrax.

Pathogenesis and disease: a special bacterial infection caused by Bacillus Anthracis.

1876 ​​R. Koch isolated anthrax bacteria on artificial media and discovered spores.

1881 Pasteur is successful in making anthrax vaccines for animals.

Bacillus graphite bacteria

Big two heads and square. Dimensions 1-3 x 4- 10 micrometres, arranged individually or in long chains (Gram-positive). Lasts long in the environment or culture environment. Bacteria are not mobile, they create shell and shell is the virulence factor of bacteria.

Resistance

Nutritional form is easily destroyed by normal physicochemical factors.

Spores are highly resistant, in soil exists for several decades. Spores were destroyed at boiling temperature after 60 minutes, dry heat 140 ° C after 3 hours, chili temperature 120 ° C after 15 minutes.

Ability to cause disease

Virulence:

The bark is an important virulence factor that prevents bacteria from phagocytosis.

Toxins: there are exotoxins, which are invasive "death factors" that help bacteria diffuse quickly. The exotoxin of anthrax bacteria has weak antigen so it cannot be used to detoxify the toxin.

Causing disease in humans:

People become infected in cases of abrasions on the skin due to contact with the wastes of sick animals or the slaughter of animals that have died from anthrax. There are also cases of eating meat contaminated with cooked papa's bacteria, or getting sick by inhaling bacteria from patients with pulmonary diseases, or improper manipulations in laboratories that cause fire soup out. The main route of anthrax transmission in humans is through the skin (94-95%), through food (0.5 - 0.7%), through aerosols (aerotons) (0.3%).

Immunity: people who recover from the disease have long-term immunity and are very rare.

Animal diseases:

Anthrax (anthrax) is a disease of herbivores: sheep is most common, followed by buffaloes, cows, horses, and goats. Dead animals are often caused by septicemia. Animals get sick from eating grass and drinking water contaminated with anthrax. It may also be stung by an insect. (buffalo flies, mosquitoes, squeezed).

Experimental animals most susceptible to bacilli are guinea pigs and white mice.

In Pakistan, India, I Ran, Central Asia, Mongolia, and South Africa, this disease is more common. In Australia, Central America, Europe and America, the disease is less common and is diagnosed early and not missed. In certain areas, people get infected directly from livestock and cause dangerous acute illness even in children. The disease can be transmitted by insects (confirmed by father). In Eastern Europe zoonotic transmission is rare. But sometimes seen in butchers. Some cases of infection from skin, hats, fleece imported from India, Pakistan, and Africa are particularly dangerous in porters, workers in disinfecting facilities, or manual workers, handicraft production. Transmission can be through trauma to the skin. In addition, through the gastrointestinal tract or through inhalation, there are bacterial spores.

Anthracis bacteria cause organizational infiltration, necrosis, haemorrhage and manifestation of gelatin fibers edema. The bacteria multiply in large numbers in the skin and from there infect the bloodstream and cause infection elsewhere.

Clinical:

Skin lesions are other pustules that are common in open skin, especially the face, neck, arms or arms, which can be in one place or many places. From 1 to 5 days after a skin infection develops in the vicinity, the scald bursts and forms a scaly, red and edema surrounded by small blisters. The lymph nodes are swollen and may soften, the skin surface on the ganglia is shiny. Many clinical lesions surface cases are diverse and sometimes predominantly water burn.
The general symptoms appear after 3-4 days of pustules on the skin, when the skin is ulcerated or necrotic, the whole state falls, high fever, delirium, sepsis and even death. On average, the disease lasts from 1 to 3 weeks.
The death rate in necrotic skin ulcers ranges from 5 to 20%. Edema and sepsis are prognostic factors. Antibiotic treatment early. The prognosis is better.

Diagnose

Specimens

Take pus from the ulcer, blood, sputum, feces, other specimens: skin, fur, fibrous milk ...

Method of microscopy

Making Gram-stained specimen to detect shape, see the ability to create spores, create shells.

Isolation method

Blood agar 5%.

Normal agar medium.

After 18-24 hours in a 37 ° C incubator, see bacteria growth properties. Separate the suspect colonies into a broth medium and then test biochemical properties.

Parallel to proceed with injecting specimens under the skin of white mice or guinea pigs, the mice will die after 1-2 days, slaughter the mouse to take the viscera for the specimen and cultivate for pure isolation.

Other methods:

Ascoli reaction: is the reaction of precipitation of the ring under warm conditions in a small test tube. It is often easy to detect anthrax antigens in the feathers, skin or viscera of animals suspected of anthrax. The reaction is made up of specific pre-made antisera.

The rapid diagnostic reactions: immunology, fluorescence, callus reaction (penicillin transforms anthrax bacteria) or is diagnosed by specific phagie.

Differential diagnosis

Staph infections, Blastomycosis, Sporotrichosis in North America are very similar to Anthrax in the experiments of coccidiosis of the central area of ​​the lesion is a black blood-secreting scab around the skin with edema and redness, acute progression, no It manifests itself as a lymphadenitis that is different from that of Anthra.

Treatment

Penicillin 600,000 UI intramuscular injection for 7 - 10 days.

Or Tetraxilin 0.50 gx 5 tablets a day, if there is intoxication, cocticose should be used, effective injection.

Vaccines can be used by those exposed to potentially pathogenic factors. But it is best to closely examine the animal's diseases and its products.