epidemic encephalitis b epidemic encephalitis b dept. of infectious disease shengjing hospital cmu
TRANSCRIPT
Epidemic Encephalitis BEpidemic Encephalitis B
Dept. Of Infectious Disease
Shengjing Hospital
CMU
DefinitionDefinition
Epidemic encephalitis B is acute infectious disease caused by encephalitis B virus,usually occurs in summer &fall.The virus is transmitted by mosquito.
Pathologic lesions: cerebral parenchymaClinical feature: high fever altered consciousness convulsion meningeal irritation respiratory failure
EtiologyEtiology
Causative agent: encephalitis B virus
genus flavivirus of flaviviridae
single strain of positive-sense RNA,
virion is spheric, diameter: 15 ~ 22nm,
Resistance: unstable in environment, Sensitive to heat, disinfectants, ultraviolet rays
EtiologyEtiology
antigenicity: stable hemagglutination inhibiting Ab complement fixing Ab neutralizing Ab
EpidemiologyEpidemiologySource of infection domestic animals: pig, horse, dog poultry: chicken, duck, goose. patients:
EpidemiologyEpidemiology Route of transmission insect borne: mosquito biting , vector: mosquito, culex tritaeniorhynchus.
Survived winter mosquitoes
pigs
mosquitoes mosquitoes person
pigs
EpidemiologyEpidemiology
Susceptibility of population: universal susceptible lifelong immunity subclinical infection : overt infection
1000~2000:1
EpidemiologyEpidemiology
Epidemiologic features sporadic from July to Sep. children under 10yrs (2~6yrs) hypersporadic property
PathogenesisPathogenesis
virusmosquito biting
replication in mononuclear-phagocyte system (MPS)
onset of illness
CNS
blood streamblood-brain barrier
brief viremia
subclinical inf.
clearance
No. of virus of invasion
cellular immunity
blood brain barrier
PathologyPathology
Place of lesion: all of CNS cerebral cortex, midbrain and thalamus .
Pathologic features gross examination:
congestion hemorrhage cerebral edema soften focuses
PathologyPathology
microscopic examination: vascular lesion: endothelial cells swelling,
necrosis neuron degeneration & necrosis neurogliocyte hyperplasia & inflammatory cells
infiltration,
perivascular cuffing ,
neuronophagia.
Clinical manifestationClinical manifestation
incubation period:10~14 days (4~21days ) typical encephalitis B
Initial period crisis period convalescent period sequela period
Clinical manifestationClinical manifestation
Initial period : on the 1st to 3rd days abrupt onset fever with headache , nausea, vomiting lethargy, abdominal pain , diarrhea,
Clinical manifestationClinical manifestation
Crisis period- on the 4th ~10th days
high fever: >40 , sustained for 7~10 days.℃ altered consciousness: lethargy, confusion, delirium, stupor, semicoma, co
ma. convulsion or twitch:(40~60%) respiratory failure: 15~40%
Clinical manifestationClinical manifestation
central RF: • reason of central RF:
• lesion of cerebral parenchyma (respiratory center injury in oblongata medulla)
• cerebral edema
• brain hernia
• intracranial hypertension
• hyponatremic encephalopathy
Clinical manifestationClinical manifestation
• manifestation of central RF:
• cacorhythmic breathing
(cheyne-stokes breathing, apnea)
• brain hernia
peripheral RF:
• dyspnea, regular breathing
Clinical manifestationClinical manifestation
Other symptoms & signs of CNS
meningeal irritations (neck stiffness
Kernigs & Brudzinskis signs positive)
Deep tendon reflexes from hyperactive to disappe
ar
pathologic reflexes positive
limbs paralysis
Clinical manifestationClinical manifestation
Convalescent period
T drop to normal in 2~5 days
neurologic function regain gradually(2W)
remain some behavioral & psychologic abnormalit
ies,
aphasia, dementia, rigidity paralysis.
>6month - sequela
Clinical manifestationClinical manifestation
Sequela period aphasia
dementia
persistent paralysis
Clinical manifestationClinical manifestation
Clinical type:
mild type
common type
severe type
fulminant type
Clinical manifestationClinical manifestation
T AC CV RF DC SQ
mild <39℃ lethargy - - 5~7d -
common 39~40 ℃ semicoma ± - 10d -
severe 40~41 ℃ coma + ± >2W
+
fulminant >41℃ deep coma + + death +
Laboratory FindingsLaboratory Findings
Blood picture: WBC 10~20×109 /L
neutrophil >80%
Cerebrospinal fluid - aseptic meningitis
transparent or slightly cloudy,
pressure may be elevated
pleocytosis: 50~500×106/L
protein may be elevated mildly
glucose and chloride are normal
Laboratory FindingsLaboratory Findings
Serological test: specific IgM Ab: blood or CSF,
3~4d after onset, peak on 2 week
ELISA or indirect immunofluorescence complement fixing Ab:
2 week after onset, peak on 5~6 week,
anamnestic diagnosis
epidemiologic investigation
Laboratory FindingsLaboratory Findings
hemagglutination inhibition Ab:
5d after onset, peak on 2 week
diagnosis: 4 fold increase in titer
epidemiologic investigation
neutralized Ab
epidemiologic investigation
Laboratory FindingsLaboratory Findings
pathogenic test virus isolation: blood, CSF, brain tissue
RT-PCR : RNA
DiagnosisDiagnosisEpidemiological data:
7~9 month
<10yrs
Clinical manifestation:
fever, headache, vomiting, altered consciousness,
convulsion, meningeal irritation, pathologic
reflexes positive.
Laboratory findings:WBC, CSF, IgM
Differential DiagnosisDifferential Diagnosis
toxic bacillary dysentery
high fever,convulsion,coma.
<24h
circulatory failure: early
stool examination: WBC, RBC
CSF: normal
meningeal irritation: negative
Differential DiagnosisDifferential Diagnosis
tuberculous meningitis
CSF, meningeal irritation
purulent meningitis
other viral encephalitis
TreatmentTreatment
General therapy:
Isolation:
preventing mosquito biting, T<30℃
nursing: mouth, skin, eye,
turn over
clapping back
sputum aspiration
TreatmentTreatment
fluid & electrolyte supplementation
adult: 1500~2000ml/d
children: 50~80ml/kg/d
Symptomatic therapy high fever: T<38℃
TreatmentTreatment physical cooling
(ice bag, alcohol bathing, cold saline enema)
drug cooling
antipyretic
subhibernation:
chlorpromazine 0.5~1mg/kg/time
phenergan 0.5~1mg/kg/time
4~6h, 3~5day
TreatmentTreatment convulsion:
fever: cooling
brain edema: 20% mannitol 1~2g/kg/time
50% glucose
dexamethason
TreatmentTreatmentsedative:
valium: adult:10~20mg/time
children: 0.1~0.3mg/ kg/ time
10% chloral hydrate:
adult:1~2g/time
children: 60~80mg/kg/time
subhibernation:
TreatmentTreatment respiratory failure:
keep airway clear• sputum aspiration• turn over , clapping back, postural drainage• aerosolization• inhalation of oxygen
TreatmentTreatment reducing cerebral edema & hernia
dehydrate :
20% mannitol :1~2g/kg/time
50% glucose , vasodilator:
654-2: adult: 20mg/time
children: 0.5~1mg/kg/time
10~30 min
TreatmentTreatment respiratory stimulant:
lobeline: adult: 3~9mg/time
children: 0.15~0.2mg/kg/time
coramine: adult: 0.375~0.75g/time
children: 5~10mg/kg/time
tracheal intubation or tracheotomy, biomotor
TreatmentTreatmentConvalescent & sequela period
acupuncture massage exercise etc.
PreventionPrevention
isolating patients and pig immunization,
killing mosquito and preventing mosquito ,
vaccination:
killed virus vaccine: 60~90%
病例分析病例分析
5 岁患儿, 8月 15 日开始发热头痛,呕吐一次,次日排稀便两次,精神不振,第三天晚间开始抽搐,神志不清。查体,T40℃,急病容,脉充实有力,呼吸略促,节律整,皮肤无瘀点、瘀斑,颈强 (+) ,克氏征 (+) ,肢体肌张力增强。辅助检查:
病例分析病例分析
血 WBC 15×109/ L,便常规 WBC 0 ~ 5个/ Hp , CSF 细胞数 75×106/ L,糖3.5mmol/L, 氯化物 115mmol/L ,蛋白 0.45g/L
哪种诊断可能性大 ? 提供诊断依据及主要鉴别诊断治疗要点