St. Louis encephalitis
Introduction
Introduction to St. Louis encephalitis St. Louis encephalitis (StLouisencephalitis) is a zoonotic infectious disease caused by the St. Louis encephalitis virus. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: joint pain
Cause
Cause of St. Louis encephalitis
(1) Causes of the disease
The St. Louis encephalitis virus belongs to the group B virus of the genus Fagaceae. The virus particles are spherical, 40 to 50 nm in diameter, with a surface-protrusive capsule and a concentrated core. The chicken and duck can be agglomerated in the range of pH 6.0-7.9. Red blood cells, cold and heat resistant, can be stored in 50% glycerin in a 4 ° C refrigerator for more than 2 months.
(two) pathogenesis
After being bitten by an infected arthropod, the virus replicates in local tissues and local lymph nodes. The occurrence and persistence of viremia depends on the stage of viral replication in local tissues outside the nervous system, the speed at which the mononuclear-macrophage system clears the virus, and the specificity. The emergence of sexual antibodies, and thus the clinical manifestations of large differences.
The brain is filled with blood and water, and has extensive neuronal degeneration. There are multiple hemorrhagic foci in the brain tissue. Microscopic examination shows degeneration and necrosis of nerve cells, lymphocytes around the blood vessels, monocytes and polymorphonuclear leukocytes infiltrate, forming " Perivascular sleeves, some glial cell hyperplasia and polymorphonuclear leukocyte accumulation form nodules, lesions mainly found in the basal ganglia of the brain, brain gray matter and white matter, can also invade the cerebellum and spinal cord.
Epidemiology
Wild birds and livestock (pigs and sparrows) are mainly carriers of the virus, which are transmitted by blood-sucking such as Culex pipiens, Culex pipiens, Culex pipiens pallens and chicken thorns. Humans are generally susceptible, with agricultural, migrant workers and their family members having a high incidence of morbidity. The ratio of dominant disease to subclinical infection increases with age. The disease is endemic in North America, mainly in the Mississippi and Ohio River basins, as well as in California, Texas, and Florida. It is mainly prevalent in the south of the 21 °C isotherm and occurs in June.
Prevention
St. Louis type encephalitis prevention
Anti-mosquito, anti-mosquito and control of mosquito breeding are the main preventive measures of this disease. The detection of antibodies against birds and mosquitoes has the value of predicting the prevalence of this disease, and early effective preventive measures. There is no vaccine today.
Complication
St. Louis encephalitis complications Complications, joint pain
Concurrent bacterial infection.
Bacterial infections of bacilli, cocci, Gram-positive and negative bacteria, various organs of the body, bacterial infections can occur in all systems. It is an acute systemic infection caused by pathogenic bacteria or conditional pathogens invading the blood circulation, producing toxins and other metabolites. It is characterized by chills, fever, rash, joint pain and hepatosplenomegaly. Daily protection and reasonable maintenance of the body.
Symptom
St. Louis type of symptoms of brain inflammation Common symptoms Unexplained fever, muscle pain, nausea and vomiting, sore throat
The incubation period is 4 to 21 days. Most patients show fever, headache, sore throat, and myalgia. They recover completely after a few days. Only a few patients (more common in children and patients over 40 years old) have symptoms and signs of encephalitis. Some patients stay. There is a lighter sequelae, the old age is a high risk factor for death, and the mortality rate of adult encephalitis is 10% to 25%.
Examine
St. Louis encephalitis check
Peripheral blood neutrophils and left nucleus.
Early diagnosis can be made by detecting IgM antibodies in serum and cerebrospinal fluid by ELISA.
Diagnosis
Diagnosis and identification of St. Louis encephalitis
It mainly relies on serological examination and virus isolation. ELISA is used to detect specific antibodies in serum (or cerebrospinal fluid) for early rapid diagnosis, complement binding, serum inhibition test and ELISA to detect antibodies in the blood. Second, three weeks, antibody titers significantly increased support for diagnosis, post-mortem brain tissue isolation virus or brain tissue cryosection, confirmed by fluorescent antibody detection of the virus.
In the Americas, this disease must be differentiated from Western equine encephalitis, St. Louis encephalitis, and herpetic encephalitis.
