Overview of Leptospirosis
Leptospirosis is an acute infectious disease caused by various types of pathogenic leptospirosis, which is a human infection caused by contact with germ-carrying wild animals and domestic animals, and leptospirosis enters the human body through the skin of the exposed parts. Rodents and pigs are the main source of infection, the clinical manifestations vary in severity, the light case is like a cold, the heavy case has obvious liver, kidney, central nervous system damage, pulmonary hemorrhage and even death.
Causes
Leptospira is elongated filamentous, cylindrical, with 12 to 18 spirals, with hooks at both ends, 6 to 20 micrometers long, showing active rotational movement, with strong penetrating power, negative Gram staining, and it is easier to see shiny active spirochetes under the dark-field microscope. Electron microscopy observed its structure mainly for the outer membrane, flagellum (axoneme) and columnar protoplasm (bacteriophage) 3 parts. Leptospira aerobic, nutritional requirements are not high, in the commonly used Koch’s medium grows well, Leptospira is extremely sensitive to drying and general disinfectants, can be quickly killed. Leptospirosis of different types, the human virulence, pathogenicity is also different, to 1986 the world has found 23 serogroups and 200 serotypes. China is known to have 19 groups of 74 types, some leptospires have hemolysin or other toxins. All kinds of toxic force of leptospirosis through the human body broken skin (or normal skin) or nose, eyes, mouth, gastrointestinal mucosa into the organism. The pathogen is extremely penetrating, and can rapidly pass through the blood vessel wall or lymphatic vessels into the blood circulation, reproduce in large quantities in the blood, and invade various organs and tissues. Bacteremia is produced during the incubation period, and toxemia occurs when the bacteremia lasts for about 1 week, causing damage to the capillaries of the whole body, the lungs, liver, kidneys, heart, central nervous system and other organs.
Symptoms
The incubation period ranges from 2 to 28 days, usually 7 to 12 days. Clinical manifestations are complex and varied depending on the immune level of the infected person and the strain of bacteria infected.
1. Early stage (infected toxemia stage)
Within 3 days after the onset of the disease, the main manifestations are sudden chills, fever, body temperature up to 39 ℃, mostly flaccid fever type, may be accompanied by headache, weakness, conjunctival congestion or hemorrhage, gastrocnemius muscle pain and tenderness may appear on the first day, lymph node enlargement appeared on the second day, with the inguinal and axillary areas more.
2. Organ damage period
3-10 days after the disease, according to the symptoms are divided into different clinical types.
(1) Influenza typhoid type is a continuation of the early symptoms without obvious or severe organ damage and functional insufficiency.
(2) Jaundice hemorrhagic type i.e. external ear disease, which is less common in China.
(3) Meningoencephalitis type: Meningeal irritation occurs within a few days of the onset of the disease, and in severe cases, there may be convulsions, coma, cerebral hernia, respiratory failure, and various kinds of neurological damage.
(4) Pulmonary hemorrhage type: If hemoptysis occurs on the basis of early infectious toxic syndrome, but there is no obvious lung rales and respiratory dysfunction, it is called pulmonary hemorrhage common type. If there are progressive dyspnea, hypoxia and asphyxia, rapidly developing rales and diffuse hemorrhagic shadows in both lungs along with septic reaction to infection and poisoning, it is called diffuse pulmonary hemorrhagic type. This type develops rapidly and the disease progresses in 3 stages.
In the aura period, the patient’s color is pale, irritability gradually increases, respiration and heart rate increase rapidly, and there are scattered and gradually increasing dry and wet rales in the lungs, and there may be bloody sputum or hemoptysis.
② hemorrhagic phase If the aura period is not treated in time, the face is extremely pale in a short period of time, the lips are cyanotic, and irritability. Respiratory heart rate is significantly accelerated. The first heart sound is weakened or gallop rhythm, both lungs are covered with wet rales, and most of them have different degrees of hemoptysis.
If the condition is not under control, the condition may intensify rapidly in a short period of time (1 to 3 days), with extreme agitation, confusion, and even coma. There is phlegm in the throat, extreme cyanosis, blood gushing out from the mouth and nose (foamy), asphyxia, slow heart rate, irregular respiration or even cessation. The above evolutionary process can be as short as a few hours or as long as 12 to 24 hours. The pathogenesis of the disease may be due to the result of hypersensitivity of the organism to pathogens and their toxic substances. The reasons for this: A. The onset of the disease is rapid and violent, and the recovery is also rapid. The lung lesions disappeared quickly, no vascular rupture was seen, and the hemorrhage was through 3 processes: congestion, bruising, and overflow; B. Hormonal therapy was effective; C. Coagulation function was normal, and no DIC manifestations were seen.
3. Late stage
After 7 to 14 days of onset of the disease, most patients recovered quickly; some cases entered the late stage after early symptoms of infection and poisoning without medium-term obvious organ damage, which manifested as late complications.
Examination
1. Laboratory examination
(1) The total number of leukocytes and neutrophils in peripheral blood is normal or mildly elevated. Blood transaminases and bilirubin are elevated.
(2) Pathogen examination Indirect fluorescent antibody staining for leptospirosis is used to find it directly under the microscope with black background fluorescence method. Leptospira can be isolated from blood or cerebrospinal fluid within 10 days of the onset of the disease, and the pathogen can be detected in the urine in the second week. Direct microscopic examination with fluorescent antibody staining and toluene blue staining and other methods, the positive rate of 50%, which can help early diagnosis, inoculation of the patient’s blood or other body fluids in animals, isolation of the pathogen, the diagnosis can be confirmed.
(3) Serological tests agglutination test, enzyme-linked immunosorbent assay to determine specific antibodies have high specificity and sensitivity. Agglutinin usually appears 7-8 days after the disease, and is positive with a potency of 1:400, which can last for months to years. The double serum with more than 4-fold increase in potency in 2 weeks interval is positive. In recent years, leptospirosis can be diagnosed in the early stage of the disease by PCR method.
2.Other auxiliary examination
In mild cases, there are fuzzy reticular shadows in the lungs or thickening of lung texture disorders, and the lesions are extensive. In moderate cases, there are small dots or snowflake shadows in both lungs, with low density and blurred borders, which may be partially fused to form shadows of 2cm in size.
Diagnosis
The clinical manifestations of this disease are complex, thus early diagnosis is difficult, easy to misdiagnose and miss diagnosis. It should be combined with epidemiological characteristics. Early clinical symptoms and pathogenetic and serologic tests to determine the synthesis.
Complications
Complications are varied and are most prominent in the eye (uveitis, iridocyclitis) and brain (aseptic meningitis, occlusive cerebral arteritis), occurring in the late stage (immune response stage).
Treatment
1. General treatment
In the early stage, bed rest should be provided, high calories, vitamin B and vitamin C should be given, water and electrolyte balance should be maintained, and hemostatic agents and blood transfusion should be applied promptly in case of severe bleeding. Those with pulmonary hemorrhage should keep the patient sedated, apply sedatives as appropriate, and resuscitate on the spot to reduce accidents in the process of moving.
2. Treatment of etiology
Early application of effective antibiotics can improve the prognosis. If the treatment is too late, the organ function is damaged, and the therapeutic effect will be reduced. Early use of penicillin has the efficacy of reducing fever in advance, shortening the course of the disease, and preventing and reducing bleeding. Other antibiotics such as gentamicin, streptomycin, erythromycin, and ampicillin are also effective. Hirschsprung’s reaction occurs 30 minutes after the first dose of penicillin injection, due to a large number of leptospirosis is killed, the release of toxins caused. Its symptoms are sudden chills, high fever, headache and full strength pain, heart rate and respiratory acceleration, and can be accompanied by a drop in blood pressure, cold extremities, shock, etc., usually lasts 30 minutes to 1 hour, occasionally leading to diffuse pulmonary hemorrhage, should be immediately applied to adrenocorticotropic hormone such as hydrocortisone intravenous drip, and anti-shock, sedative drugs treatment. In recent years, domestic synthesized imidazole acid ester and metazolol have achieved better efficacy in the treatment of this disease, and both drugs can be taken orally with few side effects.
Prevention
Management of infectious sources, including rodent extermination, good management of livestock and animal host quarantine, timely detection and isolation of patients. Cut off the infectious pathway, strengthen personal protection, use multivalent vaccine for susceptible people and workers in contact with infected water for prophylactic vaccination, laboratory, epidemiology staff and new workers in the infected area, suspected and infected people do not yet have symptoms, can be injected intramuscularly with penicillin as prophylactic drugs.