Overview
This disease is an acute infectious disease caused by the B encephalitis virus infection, mainly affects the central nervous system, mainly manifested as fever, headache, nausea, vomiting, lethargy, etc. This disease is caused by the B encephalitis virus infection at present there is no effective treatment of drugs to the general treatment and symptomatic treatment and other major
Definition
Epidemic encephalitis B, referred to as B brain, is an acute infectious disease of the central nervous system caused by B brain virus infection.
The disease is seasonal, prevalent in summer and fall, and mainly transmitted by mosquitoes.
Types
According to the severity of the disease, Encephalitis B can be categorized into the following four types.
Mild type
Body temperature is mostly lower than 39℃, mostly showing clear consciousness, may have mild drowsiness, may have headache, vomiting, but most of them are not serious, the course of the disease is about 1 week.
Ordinary type
Body temperature may fluctuate at 39~40℃, there may be headache, vomiting, impaired consciousness (lethargy, coma, etc.), obvious signs of meningeal irritation (headache, vomiting, cervical rigidity, etc.), the duration of the disease is about 10~14 days, and most of them do not have symptoms of recovery.
Severe type
Body temperature persistently exceeds 40℃, there may be coma, repeated or persistent convulsions, doctor’s examination may find pupil narrowing, superficial reflexes disappear, deep reflexes first hyperactive and then disappeared, positive pathological signs, the course of the disease is usually more than 2 weeks, and some of them have different degrees of sequelae.
Extremely severe (fulminant)
The onset of the disease is rapid, body temperature rises to over 40℃ within 1~2 days, there may be repeated or persistent strong convulsions, deep coma, respiratory failure and brain hernia can occur rapidly, the case fatality rate is high, and there are often serious sequelae.
Pathogenesis
Encephalitis B is mainly endemic in Southeast Asia and the Western Pacific [6].
Except for Northeast China, Qinghai and Xinjiang, Encephalitis B is endemic in other regions of China, mainly in Guizhou, Yunnan and Sichuan.
Three outbreaks of encephalitis B epidemics have occurred in China, and no national pandemic has occurred since the 1970s when encephalitis B vaccination was administered [5].
The incidence of encephalitis B is markedly seasonal, with epidemics occurring mainly in summer and fall, i.e., July, August, and September.
The morbidity and mortality rate of encephalitis B ranges from 20 to 30%, with neurologic or neurologic sequelae in about 30 to 50% of survivors [6].
Etiology
Causes of the disease
The disease is mainly caused by infection with the B encephalitis virus and there are three basic conditions that lead to epidemics.
Source of infection
Encephalitis B is a natural epidemic disease, the main source of infection is pigs, other sources of infection can also be seen in cattle, sheep, horses, chickens, ducks, geese and other animals.
Transmission pathway
It mainly infects human beings through pig-mosquito-human transmission mode.
The main vector of Brain B is Culex tritaeniorhynchus, Aedes aegypti and Anopheles aegypti mosquitoes can also transmit the disease.
Susceptible population
The population is generally susceptible to the disease, and it is more common in children under 10 years of age, and the incidence of the disease in adults and the elderly has increased in recent years.
Risk factors
People who have not been vaccinated against BSE.
People who are immunocompromised, such as those with AIDS and those who have been taking immunosuppressive drugs for a long time.
People living in areas where BSE is endemic.
Pathogenesis
The incidence of the disease depends on the virulence and quantity of the virus, as well as the body’s immune response and defense mechanism.
When a person is bitten by a mosquito with encephalitis B virus, the virus enters into the body, if the body has strong immunity, the virus will be cleared quickly, and the infection is generally mild; if the body has weak immunity, the virus is large in number and strong in virulence, and it can cause parenchymatous lesions in the brain.
B brain microscopic lesions mainly include neuronal cell degeneration, necrosis, soft foci formation, vascular changes and inflammatory reaction, glial cell proliferation.
Symptoms
Main symptoms
The incubation period of epidemic encephalitis B is usually 10-14 days, but can be as short as 4 days and as long as 21 days. The course of the disease in a typical patient can be divided into four phases, including the initial phase, the extreme phase, the recovery phase, and the sequelae phase.
Initial phase
In the first 1~3 days of the disease, the body temperature is mostly 39℃~40℃, there may be headache, mental depression, loss of appetite, a small number of patients may have neck stiffness, apathy, there may be no obvious neurological symptoms and signs, it is easy to be mistaken for upper respiratory tract infection.
Extreme stage
On the 4th to 10th day of the disease, in addition to the worsening of the initial symptoms, there may be obvious symptoms of brain parenchyma damage.
High fever, body temperature can be as high as 40 ℃, usually the longer the fever, the higher the body temperature, the more serious the disease.
Impaired consciousness, mostly occurring on the 3rd to 8th day of the disease, may be characterized by drowsiness, coma and disorientation.
Convulsions or convulsions, which can indicate the severity of the disease, can be manifested as small twitches of the face, eye muscles, lips and mouth, limb twitching, obligatory spasm, repeated or persistent convulsions or convulsions can cause cerebral hypoxia and edema, apnea.
Respiratory failure, which is the main cause of death, is mostly seen in patients with heavy type of BSE, and can be manifested as irregular respiratory rhythm and uneven respiratory amplitude, such as shallow respiration, tidal respiration (from shallow and slow respiration gradually to deep and fast, and then from deep and fast to shallow and slow, followed by apnea), and sobbing-like respiration (expiration occurs after two consecutive inhalations as if it is the sobbing action of a child after crying in pain) and so on.
Other neurologic symptoms and signs, most often appearing within 10 days of the disease, are commonly positive for pathologic signs, and may include signs of meningeal irritation, fecal incontinence, or urinary retention.
Circulatory failure, which is uncommon and often occurs in conjunction with respiratory failure, is manifested by a drop in blood pressure, shock, and a rapid pulse rate.
Recovery period
Body temperature gradually decreases, neurological symptoms and signs are relieved or disappear, patients with severe BSE may have limb tonus, epileptic-like seizures, and most of the patients can recover after active treatment.
Most patients can recover after active treatment. The manifestations in this stage may include persistent low fever, excessive sweating, insomnia, aphasia, dysphagia, facial paralysis and so on.
Sequelae stage
5%~20% of patients with severe BSE can have different degrees of sequelae, mainly including consciousness disorder, dementia, limb paralysis, epileptiform seizures and so on [1].
Complications
Bronchopneumonia
Mostly due to the respiratory secretions are difficult to eliminate, there may be cough, cough sputum and other manifestations.
Urinary tract infection
Mostly due to Escherichia coli infection, there may be urinary frequency, urinary urgency, urinary pain and other manifestations.
Pressure Sore
Mostly due to long-term bed rest, not timely change of position, turn over and pat the back, there may be pressure parts of the skin color change, blisters, ulcers and other manifestations.
Upper gastrointestinal bleeding
Heavy type B brain patients may have upper gastrointestinal bleeding due to stressful gastric mucosal lesions, which may include vomiting blood, black stool, dizziness and pallor.
Consultation
Department of Medicine
Department of Infectious Diseases
If you have a history of close contact with a patient with BSE, a recent history of traveling to a BSE-endemic area, or symptoms such as fever, headache, and vomiting, it is recommended that you consult a doctor promptly.
Pediatrics
Children with persistent fever, diarrhea, headache, etc. are advised to consult the pediatrician.
Emergency Medicine
When symptoms such as high fever convulsion, consciousness disorder, respiratory difficulty occur, it is recommended to seek medical treatment immediately.
Preparation for medical treatment
Consultation: registration, preparation of documents, common problems
Tips for seeking medical treatment
Avoid self-medication with antibiotics and antipyretic drugs before seeking medical treatment. Patients with high fever can be cooled down physically first.
When the patient is unconscious, it is necessary to remove foreign objects from the mouth and tilt the patient’s head to one side to avoid asphyxiation.
Parents should provide the doctor with the symptoms of the child if the infant is unable to describe his/her symptoms.
Preparation Checklist
Symptom list
Particular attention should be paid to the time of onset of symptoms, special manifestations, etc.
Is there fever? How long has the fever been present? What is the highest temperature?
Is there headache, vomiting, etc.?
Is there any confusion, drowsiness, etc.?
Were there any convulsions or seizures? How long has it lasted?
Is there an irregular respiratory rhythm? Uneven amplitude?
Medical History Checklist
Is there a history of close contact with a person with BSE?
Is there a history of traveling in an area where B-brain is endemic?
Any history of mosquito bites?
Is there a history of immunocompromised conditions such as AIDS, having chronic diseases (diabetes, hypertension, etc.), use of immunosuppressive drugs, etc.?
Checklist
Test results from the last 1 month, which can be brought with you to the doctor’s office
Laboratory tests: e.g. routine blood tests, cerebrospinal fluid tests, etc.
Imaging tests: e.g. head CT, chest CT, etc.
Medication list
(Medication used in the last 1 month, if available in boxes or packages, you may bring them to the doctor)
Ibuprofen, diazepam, etc.
Diagnosis
Diagnosis based on
medical history
The disease needs to be diagnosed on the basis of history, clinical manifestations, laboratory tests, etc. The patient may have a history of the following.
Close contact with a patient with BSE.
History of traveling in the area where B-brain is endemic.
A history of being bitten by mosquitoes during the July to September season.
Clinical manifestations
There may be high fever, headache, loss of appetite, impaired consciousness, convulsions, and irregular breathing.
Signs of meningeal irritation (headache, vomiting, neck stiffness) may be present.
Laboratory Tests
Blood tests
Blood tests in patients with encephalitis B may show an increase in the total number of leukocytes and the percentage of neutrophils, while some patients may have normal blood picture.
Cerebrospinal fluid examination
Cerebrospinal fluid examination can assist in the diagnosis of Encephalitis B and in the differential diagnosis of purulent meningitis and epidemic cerebrospinal meningitis.
In some patients, cerebrospinal fluid examination may be normal in the early stage of the disease.
Cerebrospinal fluid is aseptic meningitis changes, colorless and transparent or slightly turbid, elevated pressure.
Leukocytes in the cerebrospinal fluid are mostly in the range of (50-500) × 106/L, with a few exceeding 1,000 × 106/L, but this is not related to the severity of the disease.
The cerebrospinal fluid has mildly elevated protein, normal or high sugar, and approximately normal chloride.
Serologic examination
Positive anti-Encephalitis B virus IgM antibodies in blood or cerebrospinal fluid in patients who have not been vaccinated against BSE within 1 month is an early diagnostic indicator.
Positive anti-Encephalitis B virus IgG antibody in serum during the recovery period or a 4-fold or more than 4-fold increase in the titer of neutralizing antibody to the encephalitis B virus compared with that in the acute period are diagnostic indicators.
Negative anti-Encephalitis B virus IgG antibody in the acute stage and positive in the recovery stage are diagnostic significance.
Pathogenetic examination
The basis for confirming the diagnosis of BSE.
It is not easy to isolate BSE virus from the blood and cerebrospinal fluid of BSE patients, but BSE virus can be isolated from the brain tissues of BSE patients who died within 1 week.
Specific nucleic acids of BSE virus can also be detected in tissues or body fluids of BSE patients by direct immunofluorescence or PCR.
Imaging
Cranial CT examination
The extent and nature of brain lesions can be observed. In the acute stage, CT of the head may show hypodense shadows in the thalamus and basal nuclei.
Chest CT
Can assist in the diagnosis of signs of lung infection.
Differential diagnosis
Toxic bacillary dysentery
Similarities: both occur in summer and fall, both are more common in children under 10 years of age, both may present with high fever and convulsions.
Differences:
Cerebrospinal fluid may show signs of meningeal irritation, leukocytosis, and cerebrospinal fluid is not easy to isolate the cerebrospinal fluid of the cerebrospinal fluid of the cerebrospinal virus.
Toxic bacillary dysentery usually has no meningeal irritation signs, cerebrospinal fluid is mostly normal, anal swab or fecal microscopy may have a large number of pus and leukocytes.
Septic meningitis
Similarities: both may present with central nervous system manifestations such as impaired consciousness and convulsions.
Differences:
Encephalitis B is most common in summer and fall, with parenchymal brain lesions and aseptic encephalitis changes in the cerebrospinal fluid.
Septic meningitis is mostly seen in winter and spring, with meningitis manifestations, and the cerebrospinal fluid mostly shows bacterial meningitis changes, and bacteria can be found by smear and culture.
Tuberculous meningitis
Similarities: both may present with fever, headache, vomiting, etc., and both may present with positive signs of meningeal irritation.
Differences:
B meningitis is most common in summer and fall, the onset of disease is more acute, with the brain parenchymal lesions prominent, cerebrospinal fluid is usually not easy to detect B meningitis virus.
Tuberculous meningitis has no obvious seasonality, mostly with a history of tuberculosis, slow onset, less severe parenchymal lesions, and Mycobacterium tuberculosis can be detected in cerebrospinal fluid smears or cultures.
Other viral meningitis
Similarities: both may present with high fever, headache, and impaired consciousness.
Differences:
Encephalitis B is caused by the encephalitis B virus and can be diagnosed with the aid of epidemiologic and laboratory tests.
Other viral meningitis, can be seen in herpes simplex virus, enterovirus, etc., can be diagnosed by serology or virus isolation assistance.
Treatment
Therapeutic goal: to control the progression of the disease, to prevent and reduce complications, and to reduce the morbidity and mortality rate.
Treatment principle: there is no specific treatment drug for meningitis B, so it is necessary to actively take general treatment, symptomatic treatment, etc., focusing on the treatment of high fever, convulsions, respiratory failure and other critical symptoms.
General treatment
Brain B is an acute infectious disease, and patients need to be isolated in wards with anti-mosquito and cooling facilities.
For comatose patients, regular turning, back patting, sputum suction care is needed, and fall prevention is also required.
Patients need to be rehydrated with appropriate amount of fluids, which should not be excessive to avoid aggravating cerebral edema.
Symptomatic treatment
The key to the treatment of encephalitis B is the control of high fever, convulsions, and respiratory failure.
High fever
Can be cooled down by physical, drug, sub-winterization therapy, so that the anal temperature is about 38 ℃. It should be noted that the cooling should not be too fast or too violent.
Convulsions
If the convulsions are caused by high fever, cooling therapy is needed.
If the convulsion is caused by cerebral edema, you can apply mannitol, furosemide dehydration treatment, the use of drugs need to follow the doctor’s instructions.
If the convulsions are caused by brain parenchymal lesions, diazepam, chloral hydrate and other sedative antispasmodic can be applied, and the medication needs to follow the doctor’s prescription.
Respiratory failure
Patients with respiratory failure can be given nasal cannula or mask oxygen therapy, and tracheotomy and tracheal intubation if necessary.
Patients with respiratory failure caused by cerebral edema need to strengthen the dehydration treatment, can also be given vasodilators to improve microcirculation, reduce cerebral edema treatment.
For respiratory secretion obstruction caused by respiratory failure patients need to be given suction, sputum, anti-infection treatment.
For central respiratory failure patients can be given respiratory stimulant therapy, such as niclosamide and so on.
Circulatory failure
Circulatory failure may occur in patients with BSE and may be treated with rehydration, cardiac stimulation, and elevation of blood pressure according to the condition.
Adrenocorticotropic hormone
At present, there are different opinions on the use of hormones, which should be used according to the condition under the guidance of doctors.
Recovery and after-effects treatment
Strengthen nursing care to prevent complications, such as reducing pressure sores.
Functional exercise is needed.
According to the condition, combine with Chinese medicine, hyperbaric oxygen and other treatments.
Prognosis
Cure
For light and ordinary patients, most of them can be cured after active treatment, for heavy and very heavy patients, the mortality rate is higher, up to more than 20%, and the survivors may be left with different degrees of sequelae [1].
If not treated promptly and aggressively, respiratory failure may occur and lead to death.
Hazards.
Patients with B-brain may develop respiratory failure, circulatory failure, convulsions or convulsions, and even cause death.
Patients with B-brain may develop sequelae such as aphasia, impaired consciousness, paralysis, etc., which affects the normal life of the patients.
Daily
Daily Management
Dietary management
Diet needs to be nutritionally complete, with a combination of meat and vegetables, and fresh fruits and vegetables can be eaten appropriately.
For patients with impaired consciousness who are unable to eat normally by themselves, gastric tube can be given.
Life management
Keep the mouth and skin clean.
Pay attention to rest and maintain good work and rest habits.
Pay attention to the cleanliness and hygiene of the living environment.
Prevention
Prevention should be based on a combination of anti-mosquito, anti-mosquito and preventive vaccination measures.
Patients who have not been vaccinated against BSE can be vaccinated against BSE, which can effectively protect susceptible people.
Mosquito is the main vector, timely anti-mosquito and mosquito killing can play an effective role.
Do a good job of environmental hygiene of domestic animals, human and animal living places are separated.