兒科學(xué)教學(xué)課件：13-chickenpox

1、VARICELLA(Chickenpox)Overview Varicella (chickenpox) is the primary infection caused by varicella-zoster virus (VZV) .After varicella, the virus establishes latent infection in dorsal root ganglia and its reactivation causes herpes zoster (shingles). Varicella is characterized by the appearance on t

2、he skin and mucous membranes of successive crops of typical vesicles, generally accompanied by a mild constitutional reaction. Varicella-zoster virus (VZV) Classification: double-stranded DNA virus Family: Herpesviridae Subfamily: Alpha herpesvirinae Serotype: Only one Locations: Patients respirator

3、y secretions, blood, vesicle fluidResistance: Sensitive to heat, acid and disinfectant EtiologyInfectious sources PatientsThe infective stage is from about 24 hr before the appearance of the rash to all lesions are crusted Routes of transmission Respiratory transmission: spread by droplet Direct con

4、tact Mother-to-fetus transmission： congenital varicellaPopulation susceptibility 90% of reported patients are under 10-yr of age. The peak age of incidence is 2-6 yr.Peak seasons: winter and springEpidemiologyrespiratory secretions or skin lesion respiratory mucosaregional lymph nodes viremiamononuc

5、lear cells viremiarespiratory mucosa, skin, organs Pathogenesis V-z-vPathologyMaculopapuleVesiclesCloudy vesiclesCrustAngiotelectasis in dermisBallooning degeneration in celllayerApocytes invade in vesicle fluidvesicle fluid absorbedOther organsClinical Manifestations The severity of the disease var

6、ies from a few lesions with little evidence of systemic illness to many hundreds of lesions and extreme toxicity1.Typical varicellaIncubation period: the incubation period varies from 10-21 days, but the average is 13-17 days. Prodromal period: short,mild there may be slight fever, malaise ,or anore

7、xia.Exanthem stage: 1) Rash rash development process: maculopapule- “tear-drop” vesicles-cloudy vesicles-crusts rash characteristics: appear in batches (development of several crops of rash )four kinds of rash at the same timeconcentric distributionmucosa involvement rash sequence: trunk- face and s

8、calp- -extremities rash pruritus Clinical ManifestationsgoRash featuregoRash featureExanthem stage: 1) Rash rash development process: maculopapule- “tear-drop” vesicles-cloudy vesicles-crusts rash characteristics: appear in batches (development of several crops of rash )four kinds of rash at the sam

9、e timeconcentric distributionmucosa involvement rash sequence: trunk- face and scalp- -extremities rash pruritus Clinical Manifestationsconcentric distributionExanthem stage: 1) Rash rash development process: maculopapule- “tear-drop” vesicles-cloudy vesicles-crusts rash characteristics: appear in b

10、atches (development of several crops of rash )four kinds of rash at the same timeconcentric distributionmucosa involvement rash sequence: trunk- face and scalp- -extremities rash pruritus Clinical Manifestationsmucosa involvementExanthem stage: 1) Rash rash development process: maculopapule- “tear-d

11、rop” vesicles-cloudy vesicles-crusts rash characteristics: appear in batches (development of several crops of rash )four kinds of rash at the same timeconcentric distributionmucosa involvement rash sequence: trunk- face and scalp- -extremities rash pruritus Clinical ManifestationsClinical Manifestat

12、ions2. Severe varicella: risk factors extreme toxic symptoms with temperatures ranging from 39+-40+severe rashthrombocytopeniamore complicationshigh mortalityClinical ManifestationsClinical Manifestations2. Severe varicella: risk factors extreme toxic symptoms with temperatures ranging from 39+-40+s

13、evere rashthrombocytopeniamore complicationshigh mortalityClinical Manifestations3. congenital varicella : congenital varicella congenital varicella syndrome 1) Secondery bacterial infection the skin lesions is the most common complication. Such as impetigo（膿皰）, erysipelas（丹毒）, cellulitis（蜂窩組織炎）、sur

14、gical scarflet feverComplications2) Central nervous system complications Varicella encephalitis the most common central nervous system complication.Cerebellar signs has a much better prognosis than cerebral symptoms of convulsions and coma. Overall mortality rates vary from 5-25%.About 15% of surviv

15、ors have permanent sequelae of seizures, mental retardation, or behavior disturbances.ComplicationsOther central nervous system complications Guillain-Barre syndrome（吉蘭-巴雷綜合征）Reye syndrome（瑞氏綜合征）Transverse myelitis（橫貫性脊髓炎）Facial palsyOptic neuritis, ect.ComplicationsComplications3) Varicella pneumon

16、ia uncommon in children20-30% of adults with chickenpox have clinical or roentgenographic signs of lung involvement. Recovery is usually prompt, but roentgenographic changes may persist for 6-12 wk in the more seriously ill. Fatalities have been reported. 4) Others: MyocarditisLeukocytopeniaNephriti

17、s, ect.Blood routine: a mild leukocytopenia Multinucleated giant cells:it can be demonstrated in scrapings from the floors of fresh vesicles. Virus isolation: virus can be isolated in human tissue culture cell lines. serological study Laboratory Data Epidemiologic dataAgeSeasonsHistory of contact wi

18、th patientHistory of inoculationClinical data: Typical rash The diagnosis is usually made from the characteristic clinical picture, and laboratory confirmation is rarely needed.DiagnosisDifferential diagnosis Hand-foot-and-mouth diseaseUrticaria papulosahand-foot-and-mouth diseasehand-foot-and-mouth

19、 diseasehand-foot-and-mouth diseaseUrticaria papulosaUrticaria papulosaTreatmentSymptomatic treatment:abatement of fever antipruritic agentssedationWear mittens and keeping nails shortDaily changes of clothesAntiviral therapy: Acyclovir（阿昔洛韋）Interferon-Complication treatment:antibiotic therapy if there is a superinfection with bacteriaCortical hormone is forbiddedSalicylic acid（水楊酸） agent is not be used as possiblePrevention Control of sources of infec