anthrax
Introduction
Introduction to Anthrax Anthrax is an acute infectious disease caused by Bacillus anthracis. The anthrax is mainly an infectious disease of herbivores (bovine, sheep, horse, etc.). After exposure to animals suffering from anthrax, people can be infected. I am sick. It is mainly characterized by cutaneous anthrax, followed by pulmonary anthrax (pulmonaryanthrax) and intestinal anthrax (intestinalanthrax). It can be followed by B. anthracemia and anthraxbacillus meningitis, and the mortality rate is high. Naturally occurring cases of anthrax have been significantly reduced due to economic development and improved sanitation conditions, while the use of Bacillus anthracis as a biological weapon for terrorist activities has occurred from time to time. From September 22 to November 28, 2001, there were many bio-terrorist anthrax events in the United States, including 23 cases of skin anthrax, 12 cases of inhalation anthrax (inhalationanthrax), and 5 cases of death, all of which were inhalation anthrax. By. The damage caused by anthrax to the body is mainly hemorrhagic infiltration, necrosis and severe edema of infected tissues or organs, and at the same time causes systemic toxic symptoms. Because anthrax is highly contagious and has a high mortality rate, it has become an infectious disease of great concern to governments and people around the world. basic knowledge The proportion of illness: 0.0002% Susceptible people: no specific population Infection mode: Digestive tract spread droplet spread Complications: septic shock pleurisy myocarditis meningitis
Cause
Anthrax cause
(1) Causes of the disease
Respiratory infections (29%):
In the early stages of respiratory infection, it manifests symptoms similar to the common cold or similar influenza for several days, followed by severe or even fatal respiratory failure. If the source of the disease is contacted, it will not be treated immediately before the symptoms occur, and the mortality rate is nearly 100%. The inhaled anthrax lethal dose is between 10,000 and 20,000 Bacillus anthracis spores. This form of anthrax due to historical factors and the distribution of Bacillus anthracis in nature has in the past been first encountered in pasture workers exposed to large amounts of livestock excreta or leather-related products, as well as in frequent contact with soil, hence the name wool disease. Or pick up the rotted person. Other possible exposure factors include the processing of animal horns, hair and skin.
Skin contact infection (28%):
Skin anthrax infection occurs within 1 to 2 weeks. The initial stage is nuisance, itchy skin damage or black-spotted blisters. It looks like a long-lasting black mold on a bread, followed by a large, painless necrotizing ulcer. For general indigo or most other skin lesions, skin anthrax does not cause any pain, but it still has a 20% mortality rate without treatment. Although it is lower than other forms of anthrax, it is still very high in medical statistics. The data, but there is almost no danger after treatment.
Digestive tract infections (25%):
Infection of the gastrointestinal tract will be accompanied by symptoms such as hematemesis, severe diarrhea, acute enteritis, loss of appetite, and the rate of non-treatment mortality is 100%.
(two) pathogenesis
When the body's resistance is reduced by certain factors such as malnutrition and chronic diseases, the spores invade the skin wounds, and the respiratory or digestive tracts reproduce and produce toxins and cause disease, such as human health, the amount of spores or low virulence is not Onset, a recessive infection, such as protective antigen or capsular protection pathogen is not phagocytized, or phagocytized but not killed, instead can be brought to the local lymph node by phagocytic cells, then invade the blood circulation to form sepsis after breeding, two kinds of anthrax toxin Protein components increase host sensitivity to infection and inhibit polymorphonuclear neutrophil function and inhibit host resistance. Pathogens depend on extracellular toxins and membrane polypeptides, especially toxins directly damage microvascular endothelial cells, causing vascular access. Increased permeability, reduced effective blood volume, decreased microcirculation perfusion, hypercoagulable state of the blood, DIC and septic shock, synergistic effects of exotoxin and membrane polypeptide, and pathogens can block capillaries and cause tissue loss Oxygen, thrombosis in the microcirculation, the main pathological changes of this disease for each organ, hemorrhagic tissue Run, necrosis and edema, skin anthrax is sputum-like, surrounding tissue necrosis, subcutaneous tissue severely with bloody inflammation and interstitial edema, except for different degrees of edema and hemorrhage, there is capillary thrombosis, acute mediastinal inflammation, height Jelly-like edema and hemorrhage, swelling of the bronchial and mediastinal lymph nodes, congestion and hemorrhage, a large number of pathogenic bacteria can be seen. The lesions of intestinal anthrax are mainly in the ileocecal area, showing sputum-like lesions and hemorrhagic infiltration, and meningeal involvement is extremely hyperemia, edema, cobweb The subarachnoid space may have inflammatory cell infiltration and a large number of cells.
Prevention
Anthrax prevention
1. Manage the source of infection
Segregation of suspicious patients, especially patients with pulmonary anthrax should be timely and isolated and reported, secretions, excretions and used dressings for the patients, the remaining food, indoor garbage should be burned, corpse cremation, suspicious disease Livestock and dead animals must be treated in the same way. Livestock from infected areas or from infected areas should be isolated for 5 days, and the veterinary supervision of all aspects of the acquisition, transportation, slaughtering and livestock processing of livestock and livestock.
2. Cut off the route of transmission
The contaminated fur raw materials should be carefully disinfected and then processed. At present, the best effective disinfectants are iodine, chlorine-containing lime (bleaching powder), chloramine, ethylene oxide and peracetic acid. The wastewater should be disinfected regularly. The waste hair should be treated centrally, and it is strictly forbidden to throw it away. The dead animals and their contaminated places should be disinfected. The fur production plant should be located outside the village, downwind, away from the water source, avoiding the concentration of people and animals, and the slaughterhouse must have Veterinary supervision.
3. Protect susceptible people
Workers engaged in animal husbandry and livestock processing plants and health personnel who treat and treat sick animals should be familiar with the prevention methods of this disease. Work clothes, hats, masks, etc. should be protected during work. Smoking and eating should be strictly prohibited. Washing and disinfecting should be done at work. Immediately after skin injury, rub with 2% iodine, close contact (especially with lung anthrax) and carriers can be prevented with antibiotics.
4. Vaccination
In China, the Attenuated Live Attenuated Vaccine for Human Skin Scratch is used. It can produce immunity for 2 days after inoculation. It can be maintained for 1 year. In case of epidemic situation, emergency vaccination should be carried out, and A16R strain Bacillus anthracis aerosol immunization should be applied. It is also safe and effective. The inhalation volume is 100 million bacteria/person and the seroconversion rate is over 80%. The best preventive measure is to inoculate animals in endemic areas.
Complication
Anthrax complications Complications , septic shock, pleurisy, myocarditis, meningitis
1. Septic shock and intravascular diffuse coagulation (DIC) are caused by anthrax toxin, a serious systemic inflammatory response, more common in intestinal anthrax, pulmonary anthrax and Bacillus anthracis meningitis.
2. Systemic organ migration inflammation: pulmonary anthrax often with bloody pneumonia, pleurisy, myocarditis, hemorrhagic pericarditis and meningitis, the mortality rate is extremely high.
Symptom
Anthrax symptoms Common symptoms Itching herpes subcutaneous emphysema scarring sepsis bleeding tendency pleural effusion toxemia convulsion chest pain
The incubation period of this disease is generally 3 to 5 days, the short is 12 hours, and the elderly can be 12 months.
1. cutaneous anthrax: This type is most common, accounting for more than 95% of anthrax cases, mostly in exposed skin, such as face, neck, shoulders, hands and feet.
(1) local symptoms:
Skin rash: Beginning with rash and bleeding rash, herpes appeared on the 2nd day, the swelling area expanded, and the tissue was hard and swollen.
Necrotic scarring: 3 days after the hemorrhagic necrosis of the center of the lesion, surrounded by small groups of small blisters; on the 5th to 7th day, the necrotic area collapsed into an ulcer, the bloody exudate gradually formed into a charcoal black dry, and the granulation tissue was formed under the armpit. This is the anthrax, the diameter of the black scorpion necrosis area is about 1 ~ 5cm, the surrounding swelling area can reach 5 ~ 20cm, local pain and tenderness is not significant, there is mild itching, and then the swelling gradually subsides, black sputum in 1 ~ 2 weeks of shedding, leaving granulation tissue to form scars, swollen lymph nodes, local lymph nodes in the infected area can be swollen with tenderness.
(2) systemic symptoms: systemic reaction after 1 to 2 days of onset, fever, discomfort, myalgia, headache, a small number of patients with severe toxemia and large areas of skin edema at the loose tissue, common in the face, neck, The skin of the hand and the inner thigh, etc., and local skin lesions such as herpes. When this develops into septic shock, it is called "malignant edema", and the mortality rate is high. The pulmonary anthrax is mostly primary, also Can be secondary to skin anthrax, often rushing to dry cough, low fever, fatigue and pressure in the precordial area, after 2 to 4 days, the symptoms worsened, chills, high fever, increased cough, blood stasis, accompanied by chest pain, difficulty breathing, cyanosis And sweating, sometimes subcutaneous emphysema in the neck and chest, the lungs can only smell a small amount of wet voice, not commensurate with the serious symptoms of the lungs, but also with pleural effusion.
2. Intestinal anthrax: There is an acute gastroenteritis type or acute abdomen type.
(1) acute gastroenteritis type: sudden nausea, abdominal pain, diarrhea, vomiting, stool generally no blood, with systemic fever, most patients recover within a few days.
(2) acute abdomen type: severe symptoms of systemic poisoning, chills, high fever, persistent vomiting, diarrhea, bloody watery stool, severe abdominal pain, abdominal distension, abdominal tenderness and rebound tenderness, may have ascites signs.
3. Oropharyngeal infection: When the oropharynx is infected with anthrax, severe throat pain occurs, the neck is obviously edematous, local lymph nodes are swollen, edema can press the esophagus to cause difficulty in swallowing, and compression of the airway can cause difficulty in breathing.
4. Bacillus anthracis meningitis: more anthrax secondary to other tissues and organs, through the blood line, less primary, rapid onset, chills, high fever, severe headache, frequent vomiting, mental disorders, convulsions and severe brain edema, etc. which performed.
5. Bacillus anthracis bacteremia : more secondary to lung anthrax, intestinal anthrax, can also occur after a serious skin infection, but less common, manifested as systemic sepsis: high fever, lethargy, coma, bleeding and so on.
Examine
Anthrax inspection
Peripheral blood
(1) White blood cell count: generally (10 to 20) × 10 9 /L, and some increased to (60 to 80) × 10 9 /L.
(2) White blood cell differential count: Neutrophils were significantly increased.
(3) Platelet count: platelets can be reduced.
2. Bacteriology examination
(1) Smear examination: Collect secretions, sputum, feces, blood and cerebrospinal fluid as appropriate for smear microscopy, as shown in the case of coarse gram-positive bacilli.
(2) Bacteriology culture: Bacterial culture is carried out by taking secretions, sputum, feces, blood and cerebrospinal fluid, etc., and growth can be carried out by Bacillus anthracis.
(3) Bacterial identification: The identification methods include bead wet film method, fluorescent antibody staining method and phage lysis test.
3. Animal vaccination
The above specimens were inoculated into the house, and the guinea pigs and the mice were subcutaneously. After 24 hours, local typical swelling, hemorrhage and other positive reactions occurred. Most of the inoculated animals died within 48 hours, and Bacillus anthracis was detected and cultured from the blood and tissues.
4. Serological examination
In recent years, specific antibodies have been detected by fluorescent antibody methods for rapid diagnosis.
5.Asco1i precipitation test
It is mainly used to test whether the animal's fur and organs are infected with bacteria.
X-ray film : pulmonary anthrax can be seen in bronchial pneumonia, pleural effusion, mediastinal widening and so on.
Diagnosis
Anthrax diagnosis
diagnosis
(1) Epidemiological data: combined with the occupation, work and life of the patient, such as agricultural, animal husbandry, civilian, fur, leather processing workers in close contact with herbivores. Or stay in an environment where the epidemic area lives or where the enemy may cast a biological warfare agent.
(B) clinical manifestations: according to the medical history, combined with the characteristics of various clinical types, to make a clinical diagnosis.
(3) Laboratory inspection
1. Blood: Most white blood cell counts increase, generally 10 ~ 20 × 109 / L, a few can be as high as 60 ~ 80 × 109 / L, classified by neutrophils.
2. Bacteriological examination: pathogens can be found by taking smears or cultures of different clinical types of exudates, secretions, vomit, sputum, feces, blood and cerebrospinal fluid. The subcutaneous tissue of animals such as rabbits, guinea pigs, and mice can also be inoculated with secretions, tissue fluids, or pure cultures obtained. The typical edema occurred within 24 hours after injection, and the bleeding was positive. The animals died more than 36 to 48 hours. Pathogens could be found in animal blood, tissue fluid and various organs.
3. Serological examination: agar diffusion test, indirect hemagglutination test, complement fixation test and anthrax ring sedimentation test (Ascolis'test) are helpful for diagnosis.
Differential diagnosis
1. Identification of skin anthrax and identification of sputum, cellulitis, erysipelas, etc., the infection of this type of infection is congested, pain, edema is light, there is very little skin bleeding and skin charcoal black dry; tsutsugamushi disease, local infection does not itch Red pimples, blisters, small ulcers formed after rupture, after 1 to 2 days, central necrosis formed into black eschar, but eschar is mostly in the armpit, groin, perineum, anus, may be accompanied by superficial lymphadenopathy, hepatosplenomegaly And systemic rash, positive for Proteus agglutination.
2. The identification of pulmonary anthrax needs to be differentiated from lobar pneumonia, pneumonic plague, and leptospirosis.
3. Identification of intestinal anthrax is distinguished from Salmonella enteritis, hemorrhagic necrotic enteritis, intussusception and acute peritonitis.
4. Identification of anthrax bacteremia should be differentiated from bacteremia caused by other bacteria.
