Anthrax

Introduction to anthrax Anthrax is an acute infectious disease caused by Bacillus anthracis, a zoonotic disease. People are infected by contact with sick animals and their products and the meat of sick animals. Clinically, the main manifestations are skin necrosis, extensive edema of the ulcer, eschar and surrounding tissues and symptoms of toxemia, which may lead to acute infection of the lungs, intestines and meninges, and may be associated with sepsis. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: contact spread Complications: skin anthrax, lung anthrax, respiratory failure

Cause of anthrax

Environmental factors (60%):

Human infection with Bacillus anthracis is mainly through industrial and agricultural methods. Exposure to infection is the main route of the disease. The skin is directly exposed to the diseased animal and its fur is most susceptible to infection. Inhalation of dust, aerosol or edible fungus with a large amount of anthrax spores can cause pulmonary anthrax or intestinal anthrax, respectively. Applying an unsterilized brush or biting by a carrier with insects can even cause illness. Diseased cattle, horses, sheep, camels and other herbivores are the main source of infection for human anthrax. Pigs can be swallowed by inoculating green stalks; carnivores such as dogs and wolves can be infected by swallowing sick meat and become a secondary source of infection. The secretions and excretions of anthrax patients are also contagious.

Occupational factors (35%):

The general susceptibility depends mainly on the extent and frequency of exposure to pathogens. Young and middle-aged people have more contact with sick animals, their fur and excrement, dust with spores, etc. due to occupations (farmers, herders, veterinarians, slaughterhouses, and fur processing workers), and their incidence is also high. More persistent immunity after an infection.

Pathogenesis

When a certain number of spores enter the rupture of the skin, swallow the gastrointestinal tract or inhale the respiratory tract, and the body's resistance is weakened, the pathogens are protected by their capsules, firstly local reproduction, producing a large amount of toxins, leading to tissue and organs. Hemorrhagic infiltration, billet pains and severe edema, the formation of primary skin anthrax, intestinal anthrax and lung anthrax, etc., when the body's resistance is reduced, the pathogen rapidly spreads along the lymphatic vessels and blood circulation, forming sepsis and secondary Meningitis, skin anthrax due to ischemia and toxins, the nerve fibers of the dermis are degenerated, so there is often no obvious pain in the lesions, such as human health, and the amount of spores entering the body is low or the virulence is low, then it may not Onset or latent infection.

The pathogenicity of Bacillus anthracis is mainly related to the synergistic action of various components in the toxin. The anthrax toxin can directly damage the endothelial cells of microvessels, increase the permeability of the blood vessel wall, and lead to insufficient blood volume. In addition, some biologically active substances in acute infection Increased release, which causes small blood vessels to dilate, increase vascular permeability, reduce tissue perfusion; and because the toxin damages the intima of the blood vessels, activates the internal coagulation system and releases tissue thromboplastin substances, the blood is hypercoagulable, so DIC and Septic shock is more common in anthrax. In addition, Bacillus anthracis itself can block capillaries, causing hypoxia-ischemia and thrombosis in the microcirculation.

Anthrax prevention

(1) Patients who manage the source of infection should be isolated until the wound is healed, the skin is shed or the symptoms disappear, and the secretions or excretions are cultured 2 times negative (5 days apart).

Strictly isolate sick animals, do not use their milk, dead animals are strictly prohibited to peel or cook, should be burned or add a lot of quicklime buried deep below 2m.

(2) Cut off the route of transmission If necessary, block the epidemic area, and take disinfection and sterilization measures such as boiling, bleaching powder, ethylene oxide, peracetic acid, high-pressure steam, etc. for the patient's clothes, utensils, waste dressings, secretions, and excrement. The Ascoli precipitation test is used to test samples such as fur and bone powder. The bacteria and suspected bacteria should be strictly disinfected. The animal product processing factory must improve working conditions, strengthen protective facilities, wear overalls, wear masks and gloves when working.

(3) Protecting susceptible persons

1. Strengthen health education to develop good hygiene habits and prevent skin injuries. If skin damage occurs, immediately apply 3% to 5% iodine to avoid infection.

2. Live animals and sick animals should be divided into open grazing, and live attenuated vaccination should be carried out on the herds that are exposed to sick animals.

3. For the workers engaged in animal husbandry, animal product acquisition, processing, slaughtering, etc., and the population in the affected area, inoculate the live attenuated live vaccine of Bacillus anthracis once a year. Currently, the skin scratching method is used, and the vaccine is 0.1ml each time. Drip on the outer skin of the upper arm, and draw a "well" word. The quadruple vaccine (Bacillus anthracis, T. bacillus, bacillus bacillus and Brucella) has also been proved effective.

Protected antigens were used for vaccination in foreign countries. Intramuscular injections were performed 3 times in the first year, 3 weeks apart, and 4 times after 6 months, followed by an intensive injection once a year, each time 0.5 ml.

Close contacts should be checked for 8 days, and if necessary, penicillin, tetracycline, etc. should be applied early, and the same measures can be taken for suspected patients.

Anthrax complications Complications, skin anthrax, lung anthrax, respiratory failure

1, skin anthrax: lesions occur in the hands, face, neck and other exposed skin, initially red papules, black blood cells, ruptured and formed into black hard sputum, it is called anthrax, and there are fever, headache and other symptoms of systemic poisoning .

2, lung anthrax: caused by inhalation of Bacillus anthracis, fever, cough, sore throat, pleural effusion, difficulty breathing, death due to respiratory failure.

3, intestinal anthrax: nausea, vomiting, abdominal pain, diarrhea, fecal blood, shock, critical condition.

4, anthrax meningitis: Anthrax meningitis is a complication of various types of anthrax, the disease develops rapidly, sinister, often have severe headache, vomiting, convulsions, coma, convulsions and so on.

Symptoms of anthrax common symptoms chills high fever peritonitis chest pain toxemia dyspnea abdominal distension rash sepsis diarrhea

The incubation period is 1 to 5 days, the shortest is only 12 hours, and the longest is 12 days. The clinical can be divided into the following five types.

(1) Skin anthrax is the most common, accounting for about 95%. It can be divided into two types: anthrax and malignant edema. Carbon charcoal is more common in the face, neck, shoulder, hands and feet, etc. The skin is initially pimples or macules. Blisters appeared on the top of the 2nd day, containing light yellow liquid, and the surrounding tissues were hard and swollen. On the 3rd to 4th, the central area showed hemorrhagic necrosis, slightly subsided, surrounded by small groups of vesicles, and the edema area continued to expand, 5th to 7th. The blister necrosis is broken into shallow and small ulcers, the bloody secretions form a black like carbon block, the granulation tissue under the armpit is formed into anthrax, the surrounding tissue has non-recessed edema, and the diameter of the black scorpion necrotic area varies. 1 ~ 2cm to 5 ~ 6cm, the diameter of the edema area can reach 5 ~ 20cm, solid, pain can not, ulcers are not pus, etc., followed by edema gradually receding, black sputum fell off within 1 to 2 weeks, and then 1 Healing into sputum in ~2 weeks, fever, headache, local lymphadenopathy and splenomegaly occurred 1 to 2 days after onset.

In a small number of cases, there is no sputum formation and massive edema. Most of the affected parts are loose eyelids, neck, thighs, etc. The affected area is swollen and tough, and the expansion is rapid. It can cause large necrosis, systemic toxemia is obvious, and the condition is critical. If the treatment is delayed, it may die due to circulatory failure. If the pathogen enters the bloodstream, it may cause sepsis and secondary pneumonia and meningitis.

(2) Most of the lung anthrax are primary, caused by inhalation of Bacillus anthracis spores, but also secondary to skin anthrax, and the onset is more rapid, but generally there are flu-like symptoms of 2 to 4 days, and after remission Sudden onset, biphasic, clinical manifestations of chills, high fever, shortness of breath, difficulty breathing, wheezing, cyanosis, bloody sputum, chest pain, etc., sometimes subcutaneous edema in the neck, chest, only the scattered and scattered in the lungs Luo Yin, or signs of meningitis, physical signs and severity of the disease are often disproportionate, the patient's condition is mostly critical, often complicated by sepsis and septic shock, and occasionally secondary meningitis, if not diagnosed and rescued, often in acute 24 to 48 hours after the onset of symptoms, death due to breathing, circulatory failure.

(3) The clinical symptoms of intestinal anthrax are different, which can be manifested as acute gastroenteritis type and acute abdomen type. The former has an incubation period of 12 to 18 hours. The same eater may have severe vomiting, abdominal pain, watery diarrhea, or more. Rapid recovery within a few days, the latter onset of sudden illness, severe toxemia symptoms, persistent vomiting, diarrhea, bloody stool, abdominal distension, abdominal pain, etc., abdominal tenderness or signs of peritonitis, if not treated in time, often with sepsis And septic shock and died within 3 to 4 days after the onset of illness.

(4) Meningeal anthrax is mostly secondary to various types of anthrax with sepsis, primary occasional, clinical symptoms have severe headache, vomiting, convulsions, obvious meningeal irritation, the disease is dangerous, the development is particularly rapid, patients can start The disease died within 2 to 4 days, and most of the cerebrospinal fluid was bloody.

(5) Septicemia anthrax is secondary to pulmonary anthrax or intestinal anthrax, caused by skin anthrax, and may be associated with high fever, headache, hemorrhage, vomiting, toxemia, septic shock, DIC, etc.

Anthrax examination

(1) The total number of peripheral blood leukocytes is mostly increased, generally ranging from 10,000 to 20,000/mm3, and a few can be as high as 60,000 to 80,000/mm3, and the classification is high with neutrophils.

(2) Smear examination to take the blister contents, lesion exudate, secretions, sputum, vomit, feces, blood and cerebrospinal fluid for smear, first add 1:1000 liters of mercury to fix the spores, after staining A typical bacterium having a capsule can be found.

(3) The culture samples should be inoculated separately on blood agar plates, ordinary agar plates, sodium bicarbonate plates, blood samples should be pre-incubated and cultured, and the contaminated materials can be heated at 65 ° C for 30 minutes to eliminate the bacteria. After 4 hours of enrichment in the broth, the plate was inoculated, and if suspicious colonies were found, they were identified according to biological characteristics and animal tests.

(4) Animals are inoculated with the patient's secretions, and the tissue fluid or the obtained pure culture is inoculated into the subcutaneous tissue of animals such as mice or guinea pigs. If the injection is localized for 24 hours, typical edema occurs, and the bleeding is positive, and the animals are mostly 36. Within 48 hours of death, a large number of capsules of Bacillus anthracis exist in the animal's internal organs and blood, and the isolated suspected Bacillus anthracis application test.

(5) Identification test to distinguish between Bacillus anthracis and various types of Bacillus anthracis (Bacillus subtilis, Bacillus cereus, Corynebacterium, Thermophilus, etc.), mainly with bead wet film method, specific fluorescent antibody (antibacterial, anti-antibiotic Capsule, anti-spore, anti-phage, etc.) staining method, W phage lysis test, sodium bicarbonate agar plate CO2 culture method, penicillin G inhibition test, animal pathogenic test, capsular swelling test, dynamic test, hemolysis test, water poplar Acid glycoside fermentation test, etc.

The above various inspections should be carried out in a laboratory with special protection.

(6) Immunological tests include indirect hemagglutination, ELISA, enzyme-SPA, and fluorescent immunoassay to detect various antibodies in serum, especially capsular antibodies and serum anti-toxic antibodies. For sexual diagnosis and epidemiological investigation, the Ascoli precipitation test is mainly used to test whether the organs, skin, hair, etc. of the animal are infected with bacteria, but this method often has false positives, and the results should be judged with caution.

Diagnosis and identification of anthracnose

Diagnose based on

The occupation, work and life of the patient, such as farmers and herdsmen who have frequent contact with cattle, horses, sheep, etc., work in fur with bud dust environment, workers in leather processing factories, etc., have important reference value for the diagnosis of this disease. Skin anthrax has certain characteristics, it is generally not difficult to make a diagnosis. When a factory worker has a respiratory infection, especially when the symptoms and signs are not commensurate, he should be vigilant. The possibility of pulmonary anthrax is considered. The diagnosis depends on various secretions and excretion. Smear examination and culture of substances, blood, cerebrospinal fluid, etc., smear examination is the easiest. If you find a typical capsular bacillus, the diagnosis can be basically established, fluorescent antibody staining, bead wet film inspection, specific phage test, Diagnosis can be further established by animal inoculation or the like.

Skin anthrax must be differentiated from sputum, cellulitis, sputum sputum sputum, rabbit fever, etc., lung anthrax needs to be differentiated from various pneumonia, pneumonic plague, intestinal anthrax and acute bacillary dysentery and acute abdomen, Meningitis and sepsis anthrax should be differentiated from various meningitis, subarachnoid hemorrhage and sepsis.

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