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Plague (plague) is a severe infectious disease caused by Yersinia pestis. It is an international quarantine infectious disease and a Class A infectious disease among the legal infectious diseases in China. It ranks first among 39 legal infectious diseases. Plague is a natural epidemic infectious disease, mainly prevalent among rodents, and rats and marmots are natural hosts for Yersinia pestis. Rat flea is a vector. Clinical manifestations include high fever, painful lymphadenopathy, cough, expectoration, dyspnea, bleeding, and other severe symptoms of toxins. The disease is highly contagious and has a high mortality rate. The plague has had many pandemics in the history of the world, and there were many epidemics in China before liberation, which has been greatly reduced, but there are still sporadic cases in the west and northwest of China.

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2017-11-09 18:11 Nearly 30 million people died in three years, the disease took 150 years for the population of Europe to rejuvenate 2017-11-09 18:11

Since ancient times, human beings have encountered numerous plagues, some of which are particularly serious and have a great impact on human offspring. ... more

Basic Information

English name: plague
Visiting department: Infectious Diseases
Common causes: Rat flea bites are the main route of transmission of Yersinia pestis

Common symptoms: Fever, symptoms of toxemia, lymphadenopathy, pneumonia, bleeding
Contagious: Have
way for spreading: Rat flea bites, droplets, skin wounds, digestive tract infections

Plague epidemiology

(I) Source of infection

Sources of infection are rodents and other rodents, with brown house rats and yellow breasted rats being the main source of infection. Wild foxes, wild wolves, wild cats, hares, camels and sheep may also be the source of infection. The patient is a source of pneumonic plague.

(II) Transmission

1. Rat flea bites spread

Rat flea bites are the main route of transmission, which can transmit pathogens (Yersinia pestis) on animals to humans, forming a "rodent fleas human" transmission method.

2. Respiratory infections

Patients' respiratory secretions carry a large amount of Yersinia pestis, which can be transmitted from person to person through respiratory droplets, and can cause a pandemic in humans.

3. Transcutaneously

Contact spread. Infected skin and mucous membranes of healthy people can come into contact with the patient's pus and blood, sputum, or the flesh and blood of diseased rodents.

(Three) crowd susceptibility

The population is generally susceptible, with no differences in age or gender. Field workers, hunters and herdsmen who are in close contact with marmots are at high risk. Lasting immunity can be obtained after infection, and certain immunity can be obtained by vaccination.

Plague clinical manifestations

According to clinical manifestations and disease characteristics, plague can be divided into mild plague, bubonic plague, pneumonic plague, sepsis plague, and other types of plague. The incubation period is different for different types, 2 to 8 days for bubonic plague, several hours to 2 to 3 days for pneumonic plague, and 9 to 12 days for those who have been vaccinated.

(1) Light Plague

Irregular hypothermia, mild systemic symptoms, swelling and pain in local lymph nodes, occasional suppuration, and no bleeding, more common in the early or end of the epidemic and those who have been vaccinated

(B) bubonic plague

Most common, often occurs early in the epidemic. Acute chills, high fever, headache, fatigue, sore body, nausea, vomiting, restlessness, skin bruising, bleeding. Lymph nodes in the drainage area of rat flea bites were swollen and painful, developing rapidly, reaching a peak on the second to fourth day. Inguinal lymph nodes are most commonly affected, followed by axillary, neck, and submandibular lymph nodes. Due to the severe inflammation of the lymph nodes and surrounding tissues, patients often have a forced posture. If left untreated, the enlarged lymph nodes will quickly pus, ulcerate, and die from secondary pneumonia or sepsis within 3 to 5 days. If the treatment is timely or mild, the enlarged lymph nodes will gradually dissipate, and the wound will heal and recover.

(3) Pneumonic plague

According to the route of transmission, primary pneumonic plague and secondary pneumonic plague are divided.

1. Primary pneumonic plague is caused by direct infection of the respiratory tract. It is more common at the peak of the epidemic, it develops rapidly, and has a high fever. The symptoms of systemic poisoning are obvious. Chest pain, cough, and sputum appear within a few hours after onset. Dyspnea and cyanosis quickly increase. Wet murmurs can be heard in the lungs, respiratory sounds are reduced, and signs and symptoms are often out of proportion. Severe patients die from heart failure and shock more than 2 to 3 days.

2. The secondary pneumonic plague is based on the bubonic plague and septicemia plague. The secondary pulmonary infection has the same clinical manifestations as the primary pneumonic plague.

(IV) Septicemia Plague

Also known as fulminant plague, which can be divided into secondary and primary, primary is rare. Secondary sepsis plague develops rapidly, with systemic toxemia symptoms, bleeding, unconsciousness, delirium, or coma in a short period of time. Patients often die within 3 days. Due to extensive bleeding, ecchymosis, and cyanosis of the skin, the body was purple-black after death, commonly known as "black death."

(V) Other rare types

Skin type: Painful erythema appears at the bite of rat flea, and herpes and pustules are formed rapidly. It can be mixed with blood and can form pimple and pimple. The surface is covered with black crusts, dark red around, and hard ulcers at the bottom, which resemble skin anthrax. Occasional systemic herpes, similar to smallpox or chicken pox. Eye type: The bacteria invade the eye, causing conjunctival congestion, swelling and pain, and even the formation of purulent conjunctivitis. Throat type: Pathogens invade from the mouth, causing acute pharyngitis and tonsillitis, which may be accompanied by cervical lymphadenopathy, which can be asymptomatic recessive infection, but Yersinia pestis can be isolated from culture of throat secretions, mostly Those who have received immunizations. Enteritis type: In addition to systemic symptoms, there are vomiting, abdominal pain, diarrhea, acute aftermath, and mucus, and bacteria can be detected in stool. Meningitis type: primary or secondary, with obvious symptoms of meningeal irritation, cerebrospinal fluid is purulent, Yersinia pestis can be detected by smear and culture.

Plague laboratory inspection

(1) Routine inspection

1. Blood routine: the total number of white blood cells and neutrophils in peripheral blood, red blood cells and platelets can be reduced to varying degrees.

2. Stool routine: blood samples or mucus bloody stool, occult blood can be positive.

3. Urine routine: proteinuria, hematuria, various cast urine can occur.

(II) Etiological examination

Blood, pus, sputum, cerebrospinal fluid, and lymph node puncture fluid were taken for bacteriological examination. General inspection procedures include microscopy, bacterial culture, plague phage lysis test and animal experiment, referred to as the four-step test. The positive results obtained in the above four steps can confirm the diagnosis of plague.

(Three) serological examination

(1) Fluorescent antibody staining microscopy (IFA) has the advantages of rapidness, sensitivity, and specificity, but there are false positives or false negatives.

(2) Indirect hemagglutination (IHA) is a rapid, sensitive, and highly specific serological diagnosis method, and it is one of the effective rapid diagnosis methods.

(3) The radioimmunoprecipitation test (RIP) is sensitive and highly specific. It is not only one of the more ideal methods for plague monitoring and tracing, especially for the follow-up diagnosis of light and atypical cases. It has certain limitations as a supplement to IHA. Practical value.

(4) The coagulation improvement method of staphylococcal protein A (SPA-IHA) has a higher detection rate than indirect hemagglutination, and the method is simpler and more suitable for basic field experiments.

4. Polymerase chain reaction (PCR) detection

Diagnosis can be made within hours and is a fast and highly specific method. It is of great significance for plague surveillance, early clinical diagnosis and molecular epidemiological investigation.

Plague diagnosis

Early diagnosis, especially the timely detection of the first case, is essential for the prevention and control of plague. In endemic areas, particular attention should be paid to the initial or sporadic atypical cases. Based on epidemiological data and typical clinical manifestations, a diagnosis can generally be made. Mild cases need to be distinguished from acute lymphadenitis, roundworm disease, leptospirosis, and rabbit fever. Bacteriological or serological examinations are required for suspicious individuals. The detection of Yersinia pestis is the most important basis for diagnosis.

Plague treatment

Treatment principle

(1) Strict isolation and disinfection should be strictly isolated in the isolation hospital or isolation ward. The ward must be free of rats and fleas. Patients should be hygienically treated (changing clothes, killing flea and disinfecting) when admitted to the hospital. The ward and the room are regularly disinfected, and the patient's excreta and secretions should be thoroughly disinfected with bleach or lysine. Workers should wear the "five tights" protective clothing, wear cotton gauze masks, high-top rubber shoes, thin rubber gloves and protective glasses when nursing and diagnosing patients.

(2) In the acute phase of diet and rehydration, a liquid diet should be provided, and sufficient liquid should be supplied, or intravenous drip of glucose and normal saline should be given to facilitate excretion of toxins.

(3) Nursing strictly adheres to the isolation system, does a good job of nursing, eliminates patient concerns, and achieves the purpose of quiet rest.

2. Pathogen treatment

The principle is early, combined, adequate, application of sensitive antimicrobials.

(1) Streptomycin is a specific medicine for treating various types of plague. In severe cases, the dose should be increased. Streptomycin can be used in combination with sulfa or tetracycline to improve the efficacy.

(2) Gentamicin is divided into intravenous drips.

(3) A larger amount of tetracycline should be used in the first 2 days. Can not be changed to intravenous infusion when oral; change to oral after fever.

(4) Sulfa drugs should be used for mild and bubonic plague, and taken with the same amount of sodium bicarbonate; intravenous infusion when not available, and discontinued after normal body temperature for 3-5 days.

(5) -lactams, quinolones and third-generation cephalosporins can also be used.

Plague prognosis

The prognosis of pneumonic plague and sepsis plague is extremely poor. In recent years, due to timely diagnosis and timely application of antibacterial drugs, the mortality rate has dropped to about 10%. The key to improving the prognosis lies in early diagnosis and timely treatment.

Plague prevention

(I) Strictly control the source of infection

1. When the management patient finds a suspected or confirmed patient, he should immediately report the epidemic situation by emergency telephone and network. The urban area shall not exceed 2 hours, and the rural area shall not exceed 6 hours. At the same time, patients are strictly isolated, and visits and patients are not allowed to come and go. Patient excreta should be thoroughly disinfected, and patient death should be cremated or buried. Strict isolation is required for patients with pneumonic plague. All types of plague patients should be isolated separately. Pneumonic plague patients should be in a separate room. They should not be in the same room as other plague patients. The bubonic plague was quarantined until the lymphadenopathy completely dissipated and then observed for another 7 days. The patients with pneumonic plague were isolated until the sputum culture was negative 6 times. Plague contacts should be quarantined for 9 days. For those who have been vaccinated, the quarantine period should be extended to 12 days.

2. Eliminate the source of animal infections. Monitor the plague among the natural sources of plague, control plague among plagues, and launch a patriotic sanitation campaign.

(2) Cut off the transmission route

1. Flea patients should be sprayed with safe and effective insecticides on their bodies and clothing to kill fleas. Flea must be thoroughly removed, and cats, dogs, livestock, etc. must also be sprayed with medicine.

2. Strengthen transportation and national mirror quarantine. Foreign vessels, vehicles, and airplanes from the source of the epidemic shall be subject to strict frontier health quarantine, rodent and flea disinfection shall be implemented, and passengers shall be kept in isolation for inspection.

(3) Protecting vulnerable people

1. Protection of contacts: Avoid contact with rat fleas during epidemics. After contact with suspected or confirmed pneumonic plague patients, use doxycycline to prevent them.

2. When vaccination has begun to spread among the rats, the residents in and around the epidemic area and the staff entering the epidemic area should be vaccinated. Commonly used are dry live vaccines of EV non-toxic strains, which are inoculated by the skin scratch method, that is, 2 drops of bacterial solution, 3 to 4 cm apart. Immunization is available after 2 weeks. The current vaccine still does not provide long-term immune protection against bubonic plague and pneumonic plague. Therefore, it is generally vaccinated once a year and re-vaccinated after 6 months if necessary. The newly-developed 06173 vaccine in China produced twice as much F1 antibody as the EV strain.

3. Personal protection of medical personnel Medical personnel entering the epidemic area must be vaccinated against vaccination, and can enter the epidemic area two weeks later. Wear protective clothing, masks, hats, gloves, protective glasses and rubber shoes when working.

4. When there is an epidemic situation, do not travel to the epidemic area, minimize activities in the epidemic area and avoid contact with rodents. People who have been to the epidemic area should see a doctor in time if they have fever, chills, hemoptysis, lymphadenopathy, and other symptoms within 14 days.