plague
Introduction
Plague introduction Plague is a strong infectious disease caused by the spread of Yersinia pestis. It is a natural epidemic disease widely spread among wild rodents. Clinical manifestations of fever, severe toxemia symptoms, lymphadenopathy, pneumonia, bleeding tendency. The plague has had many pandemics in the history of the world. The number of deceased is tens of millions. In China, there were many epidemics before liberation, and the mortality rate was extremely high. basic knowledge The proportion of illness: 0.001% Susceptible people: no special people Mode of transmission: insect vector transmission Complications: sepsis
Cause
Plague cause
Rat bites (25%):
The rat bite is the main transmission route, and the transmission of rodents human is the main mode of transmission of bubonic plague. The main medium is more than 10 species of mites such as xenopsylla cheopis.
Respiratory infections (30%):
Through the droplets of the respiratory tract, people with lung and lung diseases spread through the way of breathing, talking, coughing, etc., by means of droplets forming "people people", and can cause a pandemic in human plague.
Skin infections (15%):
Transdermal transmission, peeling off the skin, flesh of the diseased rodent or the pus or sputum of the patient directly in contact with the skin wound.
Digestive tract infections (10%):
People eat infected meat that has not been thoroughly cooked.
Pathogenesis
After the bacteria invade from the skin, they usually reach the local lymph nodes through the lymphatic vessels, causing primary lymphadenitis and surrounding tissue inflammation. The lymph nodes are highly congested, and the lymph nodes involved in the hemorrhage can fuse with each other. The surrounding tissues are edema, hemorrhage, and the lymph nodes contain a large number of germs and Toxin, into the bloodstream caused by systemic infection, sepsis and severe toxic symptoms, such as the disease does not continue to develop, that is, become a clinical bubonic plague, if the bacteria enter the lung tissue through the blood can produce secondary pneumonic plague, and then the pathogens discharged from the respiratory tract It can cause primary pneumonic plague by passing it to others. All kinds of plague can cause secondary septic plague. In severe cases, the skin, lymph nodes or lung damage can be extremely light, and quickly become the primary septic plague. The basic lesions of plague are damage of blood vessels and lymphatic endothelial cells and acute hemorrhagic necrotizing changes. The boundaries of lymph nodes and medulla are unclear, coagulative necrosis, microscopic examination shows congestion, edema, hemorrhage, cell degeneration and Necrosis, inflammatory cell infiltration and bacterial mass, etc. Pneumonic plague is often bronchial or large-leaf, gas Extreme congestion bronchial mucosa, containing a lumen bloody foamy exudate, body skin and mucous membrane bleeding, often bloody serous exudate, organs and tissues have congestion, edema, hemorrhage or necrosis.
Prevention
Plague prevention
1. Manage the source of infection, strengthen international quarantine, prevent the introduction of foreign countries, and isolate the suspected or confirmed patients, and report to the health and epidemic prevention agencies within 6 hours. The contact quarantine is 6 days, and the pneumonic plague is isolated to 6 times. The glandular plague is isolated until the lymph nodes are completely dissipated and then observed for 7 days. The patient's excreta and utensils should be completely disinfected or burned. The infected area should be blocked for at least 9 days. The rats should be vigorously carried out to kill rats, eliminate other epidemic animals, and control the rats. plague.
2. Cut off the route of transmission, and the mites must be thorough.
3. Protect susceptible people
(1) Personal protection: Epidemic prevention personnel entering the epidemic area should wear clothes and caps, wear masks, protective glasses, rubber gloves and boots. After contact with patients or rats, sulfadiazine or tetracycline can be used for 2 times per day. Oral streptomycin 1g divided into 2 intramuscular injections per day for 6 days, but some authors have tested the sensitivity of 12 antibacterial drugs against 382 strains of plague bacilli preserved in Gansu Province, and considered bacillus bacillus to sulfonamides. The drugs are not sensitive.
(2) Vaccination: At present, it is generally believed that several existing immunological preparations, whether it is plague live vaccine, dead bacteria or purified bacterin, have unimproved immune effects in preventing human plague, mainly after inoculation. The immune intensity is not high, and the immune effect period is short. It can not completely guarantee that the immunized population does not develop disease. In China, the use of non-toxic live vaccines is relatively easy to accept, but the scratches are shallow and the vaccines entering the human body are difficult to grasp. It can be injected subcutaneously, 1ml for adults (including 1 million non-toxic live bacteria), children reduce it, produce immunity 10 days after inoculation, reach a peak after 1 month, gradually decline after 6 months, disappear after 1 year, to ensure The immunization effect should be strengthened once every 6 to 12 months. The vaccination target is the epidemic area, surrounding population and epidemic prevention personnel. The F1 subunit vaccine and V antigen vaccine prepared by genetic recombination technology in foreign countries can produce high efficiency in experimental animals. The price of immune antibody has a satisfactory protective effect against large doses of Yersinia pestis, and it is expected to become a safer and more effective plague vaccine for clinical use.
The detection of plague bacillus must strictly enforce the rules for the management of bacillus, pay attention to prevent aerosol infection or bite prevention, animal equipment should have protective equipment, experimental culture and equipment should be disinfected in time, plague of forest rodents can be transmitted to urban rats Classes constitute a long-term threat. Prevention depends on controlling the number of urban mice and handling their excreta as well as monitoring wild animals and their predators, avoiding contact with sick animals and their bodies, and using cockroach repellents. Currently, there is no elimination of wild animals. Practicable measures of plague, in the endemic areas, it is important to reduce the habitat of rodents in the living environment. Before using drugs to kill rodents around the family, insects should be controlled to prevent the cockroaches in the animals from turning to bites. People or livestock.
Complication
Plague complications Complications sepsis
Common complications are:
Septicemia
2. Serious people can cause death.
Symptom
Plague symptoms common symptoms fatigue, toxemia, irritability, unconsciousness, difficulty breathing, low fever, nausea, abdominal pain, diarrhea, cyanosis
Latency: gland type 2 to 8 days; lung type for several hours to 2 to 3 days; once vaccinated can be extended to 9 to 12 days.
Light weight
Irregular low fever, mild systemic symptoms, local lymphadenopathy, occasional suppuration, no bleeding, more common in the beginning, end or preventive.
Glandular
The most common, often occurs in the early stage of the epidemic, chills, high fever, headache, fatigue, body aches and occasions nausea, vomiting, irritability, skin ecchymosis, bleeding, onset, you can see the lymph node swelling and pain in the drainage area Rapidly, peaking on the 2nd to 4th day, the inguinal lymph nodes are most often involved, followed by the armpits, the neck and the submandibular, due to the intense inflammation of the lymph nodes and surrounding tissues, the patient is forced to position, if not treated in time, swollen lymph nodes Rapid suppuration, ulceration, due to severe toxemia, secondary pneumonia or sepsis death within 3 to 5 days, treatment of timely or mild disease, the glandular gradual dissipation or wound healing and recovery.
3. Lung type
Can be primary or secondary to glandular type, more common in the epidemic peak, lung plague develops rapidly, rushes to high fever, symptoms of systemic poisoning are obvious, chest pain, cough, cough, and phlegm quickly change to a lot of bright red after a few hours of onset Blood stasis, difficulty breathing and cyanosis increase rapidly, the lungs can smell wet voice, respiratory sounds are reduced, signs and symptoms are often not commensurate, those who have not been rescued in time are more than 2 to 3 days died of heart failure, shock, patients before death Highly cyanotic, the skin is often black and purple, so it is known as the Black Death.
Septicemia
Can be primary or secondary, the rapid development of the primary, systemic toxemia symptoms, central nervous system symptoms and bleeding is serious, patients quickly enter unconscious, paralyzed or coma, rescue not often in time to death within 24h to 3 days.
5. Other rare types
1 skin type, painful erythema at the bite of the epidemic, rapid formation of herpes and pustules can be mixed with blood, can also form sputum, sputum, the surface is black skin, dark red around, hard ulcer at the bottom, quite Like skin anthrax, occasionally systemic herpes, similar to smallpox or chickenpox.
2 eye type, the bacteria invade the eye, causing conjunctival congestion, swelling and pain and even the formation of suppurative conjunctivitis.
3 throat type, the pathogen invades from the mouth, causing acute pharyngitis and tonsillitis, may be accompanied by cervical lymphadenopathy, can also be asymptomatic recessive infection, but pharyngeal secretion culture can be isolated from the plague bacillus, mostly accepted Vaccinators.
4 enteritis type, in addition to systemic symptoms, vomiting, abdominal pain, diarrhea, urgency and heavy mucus, bacteria can be detected in the stool.
5 meningitis type, can be primary or secondary, with obvious meningeal irritation, cerebrospinal fluid is purulent, smear and culture can detect plague.
Early diagnosis, especially the timely detection of the first patient is crucial for the prevention and treatment of plague. Especially in the epidemic areas, early epidemics or sporadic atypical cases, special attention should be paid according to epidemiological data and typical clinical manifestations. Mild cases need to be distinguished from acute lymphadenitis, ascariasis, leptospirosis, rabbit fever, etc. For suspected patients, bacteriological or serological examination is required, and detection of Yersinia pestis is the most important basis for diagnosis.
Examine
Plague inspection
1. routine inspection
The total number of white blood cells and neutrophils increase, the decrease of red blood cells and hemoglobin varies with the degree of bleeding, and the platelets can be reduced. The enteritis type may have blood samples or mucus blood.
2. Bacterial isolation and identification
Blood, pus, sputum, cerebrospinal fluid, lymph node puncture and other materials are sent for inspection. The general inspection procedures include microscopic examination, culture, plague phage lysis test and animal experiment, referred to as the four-step test. The above four steps are positive results can confirm the plague.
3. Serological examination
1 fluorescent antibody staining microscopy (IFA), has the advantages of rapid, sensitive and specific, but there are false positive or false negative.
2 Indirect hemagglutination (IHA) is a combination of plaque-specific antigen (or antibody)-sensitized red blood cells and test materials for the detection and determination of plague antibodies (or antigens), which is a fast, sensitive and specific High serological diagnostic methods can not only check live and dead bacteria, but also detect soluble antigens and contaminated and corrupt materials. It was widely promoted in China in the 1970s and is one of the effective rapid diagnostic methods.
3 Radioimmunoprecipitation test (RIP), sensitive and highly specific, is not only one of the current methods for plague monitoring, but also for the investigation of light and atypical cases. As a supplement to IHA, it has certain Practical value.
4 Staphylococcus A protein hemagglutination improvement method (SPA-IHA), higher detection rate than indirect hemagglutination, the method is more simple, suitable for field basic experiments.
4. Polymerase chain reaction (PCR) detection
Diagnostics can be made within a few hours and is a fast and highly specific method that is important for plague surveillance, early clinical diagnosis and molecular epidemiological investigations.
5. Other methods of detection include ELISA and radioimmunoassay.
Diagnosis
Plague diagnosis
Can be diagnosed based on symptoms and medical history.
Differential diagnosis
(1) Early plague should be differentiated from typhus, epidemic hemorrhagic fever, tsutsugamushi disease, and leptospirosis.
(2) Bubonic plague
Should be identified with the following diseases:
1. Acute lymphadenitis This disease has obvious trauma, often with lymphangitis, and mild systemic symptoms.
2. Lymph node disease of filariasis In the acute phase of the disease, lymphadenitis and lymphangitis often occur simultaneously, and can resolve spontaneously after a few days. The systemic symptoms are mild, and microfilaria can be found in the evening blood test.
3. Free of heat
Caused by infection from heat-free bacteria, the systemic symptoms are mild, the glandular boundary is obvious, movable, the skin color is normal, painless, no forced body posture, and the prognosis is good.
(3) The septicemia needs to be differentiated from other causes of sepsis, leptospirosis, epidemic hemorrhagic fever, and epidemic cerebrospinal meningitis. The pathogen or antibody of the corresponding disease should be detected in time, and according to epidemiology, symptoms Identification of signs.
(4) Pneumonic plague must be differentiated from lobar pneumonia, mycoplasma pneumonia, pulmonary anthrax, and leptospirosis pulmonary hemorrhage, mainly based on clinical manifestations and pathogenic examination of sputum.
(5) Skin plague should be differentiated from skin anthrax.
