Plague Lecture

2021-01-31 12:00 AM

Yersinia pestis produces both endotoxins and exotoxins. The plague toxins work to dissolve erythrocytes, dissolve fibrin to coagulate plasma

Define

Plague (DH) is an acute infectious disease caused by the bacillus Yersinia pestis, transmitted mainly by the bloodstream (by fleabites). The clinical picture is a severe systemic toxic infection. Damage to specific lymph nodes, lungs and other organs.

The plague is classified as a "very dangerous" disease and has a natural pathogen.

History of disease research

6/1894 Alexandre Yersin and Shibasaburo Kitasato independently announced that a plague agent had been isolated.

1896 A. Yersin used antisera to treat 1 patient with DH and at the same time determined the association between DH and rat disease.

1897 Masanori Ogata and Paul Louis Simond discover the role of flea mediators.

1897 Waldemar Haffkin discovered and demonstrated the effectiveness of vaccines

Human history has gone through 3 epidemics in the 6th, 14th, and 19th centuries, with hundreds of millions of deaths. Up to now, there are still some small epidemics in many countries, especially Africa and Asia.

In Vietnam: 1898 diseases first invaded in Nha Trang, then appeared in the southern provinces of Saigon, Soc Trang, Phan Thiet, Hue, Da Nang, Tay Ninh ...

1908 Teaching started in Hanoi, Lang Son, Hai Phong, Hon Gai ...

Up to now, although the disease has been controlled, it still persists in some places such as: Central Highlands, South Central ...

Epidemiology

Pathogens

Bacillus Yersinia pestis is (formerly known as Pasteurella pestis, pestis bacterium), bacilli are short, spherical-bacilli (2 head and oval), stimulate 1.5-2 ' 0.5-0, 7 micrometres. Getting Gram-negative colour, not producing spores, not moving. Grow slowly in the culture medium (aerobic and anaerobic) at the appropriate temperature 28-37 ° C, pH 7.2-7.4. No fermentation of lactose, sucrose, urea (-), indoyl (-). Poor resistance, easy to be killed by sunlight within a few hours. at a temperature of 55 ° C die in 30 minutes, 100 ° C / 1 minute. The usual disinfectants: phenol 1%, chloranil 3%, lyzyl 1% kill bacteria within minutes.

The antigens of the plague bacillus are very complex: there are 16-28 antigens, most of which have not been fully studied. Know better than that 3 types of antigens:

Shell antigen (F1) is virulent. Protect bacteria against phagocytosis.

Stem Antigen: A part of endotoxin.

V and W antigens: A virulence factor related to the ability to fight phagocytosis.

Yersinia pestis produces both endotoxins and exotoxins. The plague toxins work to dissolve erythrocytes, dissolve fibrin to coagulate plasma, which helps bacteria to invade and has leukocytic factors.

Inoculum

As a disease from animals to humans, there is a natural disease.

The source of the disease in wild rodents (about 7200 species). Mainly rats (rats, hamsters, mice, etc.).

People who have the plague or have just recovered can be a source of disease (especially pneumonic plague).

Infection

There are 4 ways of transmission - of which are mainly through blood.

Blood sugar: Stings through an insect bite. Mainly caused by the tick Xenopsylla cheopis. Secondary are: lice, lice, aphids. Blood-sucking fleas spread the disease in mice and from mice to humans.

Gastrointestinal tract: Contaminated food and water directly spread germs by mice. This infection is actually less dangerous because the plague bacillus is easily killed when boiled and cooked.

Respiratory tract: From a patient with pneumonic plague can be transmitted directly to surrounding people through sputum droplets, saliva sprayed when the patient coughs, sneezes or talks.

Skin, mucous: Through direct contact with damaged skin (rare).

The body is aware and immune

Sensitivity to the disease is high. Therefore, it is often infected at a young age, at most 5-16 years old.

Immunity: After the disease, there is a cellular and humoral immune response. Protective immunity is usually long-lasting.

Mechanism of pathogenesis and pathology

Mechanism of pathogenesis

The plague bacillus enters the body through the skin (mainly by the sting of a flea) and the mucosa (pharyngeal mucosa, gastrointestinal tract, respiratory tract). Follow the lymphatic pathway to the region, reproduces and thrives. Passing the regional lymph nodes, bacteria follow the lymphatic pathway to the systemic lymph nodes and into the blood. The bacteria only exist in the blood for a short time due to the action of macrophages of the liver, spleen and organs. The pathological process stops here and causes primary bubonic plague. Conversely, if the liver and spleen macrophages cannot be prevented, the plague bacillus reproduces and develops and can cause primary sepsis. From the blood, bacteria go to organs such as the lymph nodes, lungs, intestines, meninges and so on. causes the lymph nodes, the pulmonary form, the digestive system, the meninges can be secondary. From these secondary foci of infection, bacteria can again enter the bloodstream, making the disease worse.

From primary bodies (cutaneous, lymphoid, pulmonary), micro-emergency develops, when the body's resistance reduces bacteria to spread into the blood and cause the plague of secondary sepsis.

Pathology

Nodules: Swollen enlargement, inflammation, pus, necrosis. The structure is broken, the lymph follicles are inserted with hemorrhagic foci, necrotic foci containing many bacteria. Organized around the lymph node inflammation, oedema.

Lungs: Tracheal mucosa, bronchial congestion, pink fluid. Pulmonary oedema, blotchy pneumonia or lobar pneumonia.

Other Organs: Liver, spleen, kidney, heart etc. congestion, hemorrhage, small necrosis, depending on the level of damage.

Divide the clinical form according to the organ of damage

Primary and secondary bubonic plague.

Lymphoma of secondary and secondary septicemia.

Primary and secondary pneumonic plague.

Primary and secondary gastrointestinal plague.

Meningeal plague primary and secondary.

Primary and secondary cutaneous plague.

Symptoms study according to each clinical form

Typical normal form (primary lymph node)

The most popular form.

Incubation

Average 2-5 days, the shortest a few hours, the longest 8-10 days. There is no clinical manifestation.

Onset period

The onset of illness in healthy people is naturally tired, irritable, headache, dizziness, pain all over the body, nausea, high fever, often spikes, or chills. There is a patient with a lot of pain in the area about swollen lymph nodes.

After a few hours or 1-2 days, the disease will turn to the full stage.

Full-blown period

Lymphadenitis:   

Regional lymphadenitis is related to where the flea bites, most of the flea bites have healed, and some also encounter a purulent blister filled with plague bacillus.

The most common inflammatory ganglion sites are the groin area, the Scarpa triangle (60-80%), then armpits (14-20%), in the neck, under the jaw, along the sternum (15-18%).

Characteristics: Enlargement enlarged, very painful when walking and resting, making the patient always in a supportive position (leg flexion, arm twitching, neck twisting, etc.).

The nodule is solid, hot, and fast. Maybe an entire swollen ganglion creates a large mass 5-8 cm. The skin covering the lymph nodes is stretched and congested. The skin surrounding the lymph nodes is swollen and inflamed so that the edges of the lymph nodes cannot be palpated. Swollen lymph nodes in 6-9 days and progress in 3 directions:

Inflammatory nodules will turn pus, rupture, discharge pus and blood, necrotic matter. The hole is long-lasting, into a shrinking scar.

The ganglion becomes fibrous into a solid lump.

If treated early, the right lymph node regimen will shrink.

Toxic infection syndrome:

Constant or fluctuating high fever. The degree of fever is related to the severity of the illness. The pulse is usually fast, rapid breathing.

Headache, dizziness, fatigue, nausea. More severe: Li panic, delirious. Little dark urine. Feces may be loose ...

Congested mucosal skin, red face, red eyes. Dry lips, dirty, white - heavy tongue: bleeding under the skin, mucous membranes.

Septicemia

Account for 1-2%.

Primary sepsis

The disease starts suddenly, very acute right when the peripheral lymph node is not swollen: The infection is very serious: high fever 40-41 ° C, many chills. The patient is agitated, delirious, or lethargic. Vomiting, diarrhoea, abdominal distension, cardiovascular and respiratory disturbances. Bleeding of the skin, mucous membranes, and viscera - also known as "Black Plague".

XN: BC increased very high 20-40,000, accounting for 80-90%, but there were cases where the leukocyte decreased much <1000 / mm3. Decreased alkaline reserve shows scattered intravascular clotting.

High mortality, rapid death in the first 1-2 days is "Ultimate Plague".

Secondary sepsis

Usually appears after the lymph node, the primary lung is left untreated, when the patient has decreased resistance. The disease is usually severe, has an acute course but is usually less pronounced than the primary form.

Lung form

Primary lung form

The illness is very short, only a few hours. Onset, very suddenly, a fever of 40-41 ° C with chills. Rapid pulse decreased blood pressure. Patients see increasing fatigue, headache, and discomfort. No respiratory symptoms. After only a few hours to 1 day in the full phase with symptoms of the infection worsening systemic infection. The symptoms of clear breathing: chest tightness, shortness of breath, shortness of breath, cough with phlegm at first, then cough a lot of blood, pink, there are many bacteria. The reverse physical symptoms were poor, with little pathology being heard. X-ray: pneumonia or more scattered ghosting. If not treated promptly, the disease progresses rapidly into acute pulmonary oedema, increased dyspnea, severe cardiovascular disturbances. Quick death in 1-2 days.

Secondary lung form

More common than primary lung form. Occurrence after other bodies (lymph node, septic form) is not detected and treated promptly. The prognosis is usually severe.

Skin type

In the area of ​​bacteria invading, developing into macular, then blisters and then bloody pustules (sometimes black), the pressure is very painful. Around the pustules are blood surrounding skin organizations, infiltrates high up from the base of the healthy skin. Then the pimple ruptures, forming an ulcer, the base of the ulcer is a yellow infiltration background, the ulcer face is covered with black scabs (like anthrax). The sore takes a long time to heal and becomes a scar.

Other possible

Rarely.

Meningitis form.

Digestive.

Mucosa.

Diagnose

clinical

Syndrome of infection - severe systemic toxicity.

Symptoms depend on each individual.

Test basis

Complete blood count: Leukocytes increased, neutrophil count over 80%; Red blood cells and platelets are reduced in severe forms.

Isolation of Yersinia pestis according to the following categories: From skin acne, lymph nodes, blood, sputum, cerebrospinal fluid, etc.

Inoculated on agar medium with an added growth stimulant.

Injections to laboratory animals: mice:

Direct screening is possible

Serum diagnosis: complement combination reaction, agglutination reaction, prevention of erythrocyte agglutination. Do 2 times 10 days apart. A quadruple to the 1st antibody titer is positive.

Method for detecting the F1 antigen in the specimens.

Quick diagnosis by immunofluorescence reaction can detect the plague bacillus in the patient after 1-2 hours.

Epidemiological basis: Patients in epidemic zones.

Differential diagnosis

Common acute lymphadenitis: manifestations of infection in the vicinity, lymphadenitis with lymphadenitis. Infection-intoxication syndrome is usually not severe.

Pneumonia: Mechanical symptoms are not as prominent as pneumonic plague, but physical and radiological symptoms are typical.

Primary plague (pulmonary form, septic form) is difficult to diagnose and differentiate from sepsis, other bacterial pneumonia. Diagnosis is mainly based on epidemiology in the epidemic area and on bacterial testing and serological diagnosis.

Treatment

The principles of treatment

All patients must be treated in the hospital, isolated on the spot under the "very dangerous" disease regime (quarantine).

Treatment to kill the pathogen.

Treatment according to the pathogenetic mechanism.

Specific treatment with antibiotics

Streptomycin is an effective antibiotic. Dose: 3g / day injection 0.5g / time from 4 hours (total dose of 3g / day) ' 2 days. Then 0.5g every 6 hours (total dose 2g / day) ´ 7-10 days (normal lymph nodes).

If the bacteria is resistant to streptomycin, replace it with kanamycin 1g / day.

Other antibiotics may be used instead when patients are allergic to streptomycin:

Tetracycline: dose 50mg / kg / day x 2-3 g / day, when temperature decreases, reduce dose to 2g / day ´ 7-10 days.

Chloramphenicol 50mg / kg / day ´ 7-10 days.

Bactrim 0.48 ´ 6-8 v / day.

The new antibiotic currently works well with the plague. Group III Cephalosporin: Ceftriaxone intramuscularly or intravenously 2-3 g / 24h. or the Quinolone group

With severe plague (bacteremia, lung form) should use a combination of antibiotics: Streptomycin 2g / day + tetracycline 2g / day or streptomycin 2g / day + tetracycline 2g / day + chloramphenicol 2g / day. Currently, the class III Cephalosporin + Quinolone group of antibiotics are often used

Symptomatic treatment

Infusion, electrolyte rehydration, anti-acidosis.

Cardiovascular support.

Pain relief, fever.

Sedative.

Positive resuscitation depends on the patient's symptoms: Anti-dizziness, respiratory failure, circulatory failure, bleeding etc.

Resistance enhancement: vitamins, nutrition, diet.

Prevention

General prevention

Killing rats and fleas (pay attention to kill fleas first, kill mice later).

Room flea bites.

When there is a plague patient, it is necessary to follow a regime of very dangerous diseases.

With contacts for emergency prophylaxis: Streptomycin 1g / day ' 5 days or tetracycline 1g / day ' 5 days. Must be closely monitored, when there are symptoms, then treat the same as the patient.

When a patient dies: It is necessary to shroud the corpse with 5% chloramine-impregnated cloth, the coffin is sprinkled with lime powder, to be buried 2 m deep or cremated.

Specific disease prevention

Immunization: EV vaccine (live vaccine) inoculation or intradermal. Protection effect is not high. Assign to people living in an epidemic outbreak but not yet immune or who have to go on business to an epidemic area.