lymphocytic choriomeningitis
Introduction
Introduction to lymphocytic choriomeningitis Lymphocytic choriomeningitis (LCM) is an acute infectious disease caused by LCM virus. The clinical course of this disease may range from epidemic-like symptoms to meningitis and encephalitis. The course of disease is self-limiting and the prognosis is good. The disease is an animal infectious disease, and the natural host of the LCM virus is Rattus norvegicus. basic knowledge The proportion of illness: this disease is rare, the incidence rate is about 0.005% Susceptible people: no special people Mode of infection: bite spread Complications: orchitis pneumonia abortion
Cause
Causes of lymphocytic choriomeningitis
Cause:
LCM virus is an RNA type virus with a size of about 50 mm. It is similar in morphology and serology to Lassa virus, Machupo virus, Tacaribe virus, etc. It is also an isnavirus. The pathogen has many pathogenicity. Different types of tissue, virulence, etc., but each type has the same group-specific antigen, the virus can be inactivated at 56 ° C for less than 1 hour, and is easily destroyed in ether, formaldehyde, ultraviolet light and pH <7 In 50% glycerol, long-term storage at -70 °C, the virus can grow in chicken embryo or mouse embryo fibroblast tissue culture, and is pathogenic to mice, mice, guinea pigs, voles, rabbits, monkeys, etc.
[Pathogenesis]
The pathogenesis has not yet been fully elucidated. When the virus first invades the respiratory tract, it can multiply in the epithelial cells. Therefore, many patients present with upper respiratory tract infection or "flu-like" symptoms. The virus enters the blood and causes viremia, possibly crossing the blood-brain barrier. Infected meningeal cells, the death of this disease is very rare; therefore, there are few reports of pathological changes, the main findings are brain swelling, meningeal and choroid plexus with lymphocytes and monocytes infiltration, capillary hemorrhage, necrosis, etc. However, it has been reported that the central nervous system does not change disease, and the lesions are only found in organs such as the lungs, liver, kidneys and adrenal glands.
Prevention
Lymphocytic choriomeningitis prevention
The disease has experienced many major epidemics in history, causing major harm. At present, epidemic typhus remains one of the World Health Organization epidemiological surveillance projects. The key to its prevention lies in flood control, mites prevention and extensive mass health campaigns.
(1) Management of infectious sources
Sputum treatment. Isolation after smashing, bathing, and changing clothes. Shave the whole body hair if necessary. Women can use drugs to kill cockroaches, such as 10% of 100 alcohol rubbing hair wrapped in a towel, 1 hour after washing hair, head lice and licking eggs can be killed. Or use 30g of 30g, add 500ml of water to cook for 30 minutes, take the filtrate and wipe the root of the hair, then wrap it, and clean it the next day. For close contacts, medical examinations are on the 23rd.
(2) Cut off the route of transmission
Strengthen health education and encourage the masses to bathe and change clothes. After the patient is found, the patient and the contact person are simultaneously smashed and repeated once every 7 to 10 days. Physically kill, use steaming, boiling, washing, ironing and other methods. The temperature was maintained at 85 ° C for 30 minutes. Chemical cockroaches can be spread on underwear or mattresses with 10% DDT powder, 0.5% 666 powder or 1% malathion. To prevent drug resistance, the above drugs can be used interchangeably.
(3) Protecting susceptible persons
There are three kinds of inactivated vaccines: calf vaccine, chicken embryo or duck embryo vaccine and murine lung vaccine. Domestically used are inactivated mouse lung vaccine, which is suitable for residents in endemic areas, newly entered epidemic areas, army commanders, and epidemic prevention medical personnel. Laboratory staff, etc. The first year of subcutaneous injection 3 times, each interval 5 to 10 days; 15 years of the first injection of 0.5ml, the second and third times are 1ml; 14 years old and below are 0.3 ~ 0.4ml and 0.6 (the second time) ) and 0.8ml (3rd time). Intensive injections are given once a year, and the injection dose is the same as the third time. After more than 6 vaccinations, it can have a longer-lasting immunity, and is also effective against rickettsial infection. After the inoculation, the reaction was mild and only mild redness was observed locally. The live attenuated E vaccine has been widely used in some countries. It can be administered subcutaneously once, and the immune effect can be maintained for 5 years. Temporary preventive effects can also be obtained by taking tetracycline or chloramphenicol, but most scholars do not advocate the use of it, and can achieve satisfactory results due to early administration after onset.
(4) Vaccination
The vaccine has a certain effect, but it cannot replace cockroaches. The vaccine is only suitable for certain special circumstances, such as those who are preparing to enter the epidemic area, troops, researchers, etc. Inactivated vaccines can reduce the incidence, reduce symptoms, shorten the course of disease, and reduce the mortality rate. A commonly used inactivated mouse lung vaccine is injected subcutaneously. The first year is three times, with an interval of 5 to 10 days. The adult dose is 0.5ml, 1ml, 1ml. After the annual injection of 1ml, there is Golinevich chemical vaccine abroad, injection 1 needle. The live attenuated E strain vaccine has been widely used in some countries in the world, and can be injected subcutaneously once, and the immune effect is maintained for 5 years.
Complication
Lymphocytic plexus meningitis complications Complications orchitis pneumonia abortion
This disease can be complicated by orchitis, mumps, pneumonia, arthritis, abortion of pregnant women and so on.
Symptom
Lymphocytic choroid plexus meningitis symptoms common symptoms fatigue back pain nausea nasal congestion muscle soreness diplopia sore throat severe headache diarrhea photophobia
The incubation period of this disease is from 6 days to several weeks, and the clinical manifestations are diverse.
(1) Influenza-like
Most of the onset is rapid, fever can reach above 39 °C, accompanied by back pain, headache, body muscle aches, some patients complain of nausea, vomiting, photophobia, swollen lymph nodes, diarrhea, rash or sore throat, nasal congestion, coughing Symptoms, the course of the disease is about 2 weeks, occasionally recurrence, the feeling of fatigue after the disease can last 2 to 4 weeks.
(two) meningitis type
Can appear after the "flu-like" symptoms (often with a short-term remission period), or directly with meningeal inflammation, acute onset, manifested as fever, headache, vomiting, meningeal irritation, etc., in addition to young children, convulsions are rare, sane No change, the course of disease is about 2 weeks.
(3) Others
Meningoencephalitis type, encephalomyelitis type and other rare, manifested as severe headache, phlegm, coma, convulsions, paralysis, mental disorders, etc., some cases have neurological sequelae, such as aphasia, deafness, arachnoiditis, varying degrees of paralysis , ataxia, diplopia, strabismus, etc.
Examine
Examination of lymphocytic choriomeningitis
Peripheral blood shows that the total number of white blood cells is normal or decreased, lymphocytes are relatively increased, and every abnormal lymphocyte appears. The number of cerebrospinal fluid cells in meningitis patients can be increased to 100-3000/mm3, more than 90% of which are lymphocytes; Generally no more than 100mg / dl; sugar is normal or slightly reduced, chloride is normal, normal pressure or slightly increased.
In the acute phase, the blood or cerebrospinal fluid is inoculated into the brain or abdominal cavity of the mouse. The serum immunofluorescence test can be positive in the first week of the disease, which is beneficial for early diagnosis. The complement fixation test is positive in the course of 10 to 14 days. It reached its peak in 5-8 weeks and disappeared within 4 to 6 months. The neutralization test was only used for epidemiological investigation.
Diagnosis
Diagnosis and differentiation of lymphocytic choriomeningitis
diagnosis
Have a history of contact with voles, mice, or have rats in the same place and have similar patients nearby. After the "flu-like" symptoms are relieved briefly, the cells in the cerebrospinal fluid of the meningeal irritation are all lymphocytes, chlorides are normal and sugar Relative reduction, etc., have important reference value, the diagnosis depends on serological tests or virus isolation.
Differential diagnosis
The disease is easily confused with influenza, other viral respiratory infections, various viral meningitis, tuberculous meningitis, etc., should be identified by epidemiological data, serological examination and virus isolation, due to the presence of a small amount of blood in the surrounding blood Abnormal cells are easily confused with patients with infectious mononucleosis complicated with meningitis, but the total number of abnormal lymphocytes in the latter can reach more than 10%, and the heterophilic agglutination test is strongly positive, Epstein-Barr virus antibody (IgM type) Membrane antibody) is also mostly positive.
