tularemia
Introduction
Introduction to rabbit fever Rabbit fever, also known as Tularaemia or deer fly fever, is a natural epidemic acute infectious disease of rodents transmitted by ticks or flies. Clinical manifestations include fever, swollen lymph nodes, skin ulcers, conjunctival hyperemia, ulcers, respiratory and digestive tract inflammation and toxemia. Tulamycin can be used as a pathogen in biological warfare, and infected people will have high fever. It is full of pain, swelling of the gland and difficulty in swallowing. The disease can be easily treated with antibiotics. basic knowledge Sickness ratio: 0.00024% Susceptible people: no specific population Mode of transmission: insect vector transmission Complications: meningitis osteomyelitis pericarditis endocarditis peritonitis lung abscess meningitis
Cause
Cause of rabbit fever
The storage hosts of T. tractia are mainly rabbits and hares (type A) and caries (type B). Type A is mainly transmitted by ticks and blood-sucking insects, while surface water contaminated by rodents is an important source of infection for type B. Poultry may also be used as a storage host for this bacterium. In areas where the disease exists, sheep are more susceptible to infection, mainly transmitted by cockroaches and other blood-sucking insect bites. Dogs are rarely infected, but cats are resistant to T. Susceptible to disease, infected by blood-sucking insects, prey on rabbits or rodents, and even infected by infected cats. People are infected by contact with wild animals or sick animals. It is related to the activity of vector insects, but water source infection can also occur in autumn and winter.
(1) Causes of the disease
The pathogen of this disease is Gram-negative cocci, the size is (0.2-0.7) m × 0.2m, no power, no spore formation, aerobic, good growth in the medium containing glucose-cystine-blood agar The bacteria have strong ability to survive in water. They can survive in tap water or well water at 13-17 °C for 3 months, survive in water at 4 °C for more than 5 months, can withstand low temperatures of -30 °C, and survive in frozen meat. Month, the bacon can also survive for 1 month, direct sunlight for 30min, 56 °C for 30min, 60 °C for 10-20min can achieve physical sterilization effect, the bacteria sensitive to disinfectant, 0.1% mercuric water or 1% The phenol bath solution can be sterilized for 30s. The 0.1% cresol solution can kill bacteria in the spleen tissue for 2 minutes. According to the virulence of the strain on rabbits and the ability to decompose glycerol, the known strains in the world can be divided into three geographies. Variants: Among them, the American genus (Franicisellatularensis nearctica) which is capable of decomposing glycerol is the most toxic; the Eurasian variety (Fr. t. palaearctica), which does not decompose glycerol, is weak; the Central Asian variety (Fr.t. Mediaasiatica can decompose glycerol, but its virulence is weak, China and recent years in northern Xinjiang Isolated strains belong Eurasian variants.
(two) pathogenesis
After the pathogen invades the human body through the skin or mucous membrane, most patients can locally cause the primary ulcer lesion. The bacteria first reach the local lymph node along the lymphatic vessel, causing an inflammatory reaction, resulting in swollen lymph nodes, some bacteria are destroyed by phagocytic cells, and other bacteria are Invasion of the blood circulation, which in turn causes bacteremia, bacteria spread to various organs with blood circulation, causing a series of lesions in the heart, liver, lung, spleen, kidney and other organs, causing ulceration of the affected local skin, and spreading to deep tissues Cheese necrosis, polymorphonuclear leukocytes and epithelioid cells are usually gathered around the ulcer. Fluorescent antibody staining can detect bacteria in monocytes, large phagocytic cells and polymorphonuclear leukocytes, and deep and shallow parts connected with ulcers. Lymph nodes are often invaded and have focal necrosis and suppuration, but no peri-peripheral inflammation occurs. Lung lesions can be seen in the consolidation of substantial damage of the lung lobe and subpleural necrosis, and abscess can occur. Liver, spleen and adrenal gland may be swollen. , throat, esophagus, stomach, colon, ileum, appendix, kidney, adrenal gland, pericardium, brain and meninges, and bone marrow Organ granuloma can occur, even central necrosis or purulent may occur.
Prevention
Rabbit fever prevention
1. Inoculation of live attenuated vaccine is an effective personal preventive measure. Once vaccinated, its protective immunity can last up to 5 years. Oral attenuated live vaccine and aerosol inhalation can also be used.
2. Strengthen anti-epidemic requirements for hunting activities and health quarantine supervision of environments and objects that may be subject to pollution.
3. Carry out regular hygiene publicity and education in the occupational groups in contact with the source of infection, and pay attention to the hygiene management of water source, food, meat, fur production and processing operations.
4. Prevent bedding, rodent and other blood-sucking arthropod bites and rodent infections.
5. When entering the epidemic area, wear anti-mite protective clothing, use insect repellent and carefully look for cockroaches. When operating rabbits and rodents, especially in popular areas, wear protective clothing, including rubber gloves and masks, any cockroaches. It should be removed immediately. Bacteria can be found in the animal and in the fur of the animal's fur. Wild birds and prey must be thoroughly cooked before eating. The contaminated water must be disinfected and used.
Complication
Rabbit fever complications Complications meningitis osteomyelitis pericarditis endocarditis peritonitis lung abscess meningitis
As the disease progresses or is chronic, secondary inflammation occurs in the liver, spleen and lymph nodes, manifesting as tuberculous granuloma formation, typhoid or poisoning type may be complicated by meningitis, osteomyelitis, pericarditis, endocarditis, peritonitis, Mediastinal inflammation, lung abscess and meningitis are rare complications.
Symptom
Symptoms of rabbit fever Common symptoms Toxic septicemia, fatigue, irritability, dull pain, abdominal pain, dizziness, high fever, diarrhea, local lymphadenopathy
1. Incubation period: usually 1 week, the short is only a few hours, the elderly is 2 to 3 weeks.
2. Symptoms and signs: rapid onset, body temperature rises rapidly to 39 ~ 40 ° C, systemic fatigue, chills, headache, back pain, generalized muscle pain, and then the development of the disease, paralysis, lethargy, irritability and other acute systemic symptoms The patient's temperature rise lasted for 2 to 5 days, followed by a relief of 1 to 3 days, and slowly decreased. The local lymph nodes in the bacterial invasion site first had pain, and the skin showed primary lesions within 2 days, mostly in the hands or fingers, and began to appear red. The pimples, followed by pustules, form a central necrosis after rupture, gradually become a hard ulcer on the edge, swollen local lymph nodes, can also be broken, the course of the disease generally lasts 3 to 4 weeks, the recovery is slow, about 2 ~ 3 months or longer, the clinical features of this disease are usually divided into the following 6 types:
(1) ulcer gland type: this type is the most common, accounting for about 50% to 80%, the general symptoms are the same as before, mostly mild, and a few severe cases show toxemia.
(2) gland type: about 10% to 15% of the cases, although the bacteria are mostly invaded by the skin, but there is no primary skin lesions, mainly lymphadenopathy and fever, generally mild systemic symptoms.
(3) Eye gland type: pathogen invades the conjunctiva of the eye and causes conjunctivitis, local congestion, eyelid edema, photophobia, tearing and amblyopia. In severe cases, the cornea may cause ulceration, and the lymph nodes of the ear gland and neck are visible. Swollen.
(4) pharyngitis: exudative pharyngitis is more common, pseudomembranous and pus on the tonsils, cervical lymph nodes are common swelling, swallowing movement disorders, high fever, severe cases can be caused by tracheal obstruction, More common in children.
(5) Gastrointestinal type: often acute attack, elevated body temperature, accompanied by spastic abdominal pain and watery diarrhea, can even cause peritonitis, hematemesis, black feces and so on.
(6) Typhoid type (systemic or pleural lung type): usually no primary lesion and local lymphadenopathy, the bacteria enter the bloodstream and cause sepsis, so the symptoms of systemic poisoning are serious, clinical and typhoid are quite similar, sometimes with the pleura, Severe infection of the lungs and diarrhea, the untreated rate of death can reach 30%.
(7) Lung type: symptoms of upper respiratory tract catarrh, cough, shortness of breath, cough and dull pain after sternum, and severe toxic symptoms.
Examine
Rabbit fever check
1. Blood: In the early stage of onset, leukocytosis (10 ~ 12) × 109 / L, showing increased granulocyte, leukopenia in the late stage of the disease, and the proportion of lymphocytes and monocytes increased, there are rod-shaped nuclear neutrophils.
2. Bacterial culture: Local ulcer secretions, swollen lymph nodes, sputum, gastric lotion or acute blood samples were cultured on glucose-cystine-blood agar medium, and pathogens were isolated after 48 hours.
3. Animal inoculation: The above specimens are inoculated into the subcutaneous or abdominal cavity of mice or guinea pigs, usually within 1 week. The pathological anatomy can be found in the liver, and the spleen has granulomatous lesions, and the pathogenic bacteria can be isolated from the spleen.
4. Serological test: detection of specific antibodies, methods are: 1 serum agglutination test: antibody positive in the second week of the disease, after 1 to 2 months, the titer reached a peak, up to 1:1280, the antibody can last for several years Agglutination titer of 1:100 or higher or a 4-fold increase in antibody titer between the acute and recovery phases of the serum has diagnostic significance and can be excluded from cross-reactivity with Brucella. 2 reverse indirect hemagglutination test: with early rapid diagnosis characteristics, the results can be obtained after 1 ~ 2h. 3 immunofluorescent antibody method: can be used for early rapid diagnosis, specificity and sensitivity, 1 ~ 2h can produce results.
5. Skin test: Prepare terresin with diluted dead suspension or purified antigen, inoculate 0.1ml of bacteriocin in the forearm skin, and check the result after 12~24h, which is positive when it is red and swollen, 3~ 5 The disease can be seen on the day of the disease. The clinical diagnosis does not rule out the possibility of having this disease in the past. It is mainly used for epidemiological investigation.
6. Pulmonary X-ray: showing bronchial pneumonia.
Diagnosis
Diagnosis and diagnosis of rabbit fever
In areas with frequent disease, it is not difficult to make a diagnosis based on epidemiology and clinical manifestations. Laboratory tests such as pathogens and serology are particularly valuable. Because the bacteria can infect people, appropriate protective measures should be taken during sampling. Avoid direct contact with oral secretions and exudates from clinically ill cats.
The disease should be differentiated from skin lesions and glands such as plague, anthrax, and rat bite. In addition, the disease should also be associated with aphids, typhoid fever, snoring, skin sporotrichosis, infectious mononucleosis, tuberculosis, fungi. Infection, bacterial pneumonia, lymphoma, brucellosis, typhus, diphtheria, flu and lung cancer.
