inflammaton of the liver. hepatitis a-b viruses part І dr. osama al jiffri

INFLAMMATON OF THE LIVER

Hepatitis A-B Virusespart І

Dr. Osama AL Jiffri

HEPATITIS A VIRUS

HEPATITIS VIRUS

• Hepatitis A-B-D-C-F-E• Hepatitis A and E Viruses do not persist in

the liver• There is no evidence of progression to

chronic liver damage• Hepatitis B, D, C, may be associated with

persistent infection and progression to chronic liver disease

Hepatitis A Virus: Structure and Classification

Picornavirus genus : Hepatovirus

Member of the EnterovidaeOffcially referred to as enterovirus 72

• The virions have cubic symmetry and are 27nm• Naked icosahedral capsid• SS RNA (7400 nucleotides)• Single serotype worldwide• Humans only reservoir

Hepatitis A Structure

Fecal-oral transmission

Mode:

• Close personal contact(e.g., household contact, sex contact, child day-care centers)

• Contaminated food, water(e.g., infected food handlers, contaminated raw oysters)

HEPATITIS A VIRUS TRANSMISSION

GEOGRAPHIC DISTRIBUTION OF HEPATITIS A VIRUS INFECTION

Hepatitis A: Pathogenesis

• Incubation 4 weeks (range 2-6 weeks)

• Particularly in young children

• Replicates in hepatocytes (little damage to cells) released via bile to intestines 7-10 days prior to clinical symptoms

Hepatitis A: Clinical Features-1

– An acute illness with:• Clinical illness usually starts with a few days of

malaise, loss of appetite, fatigue, abdominal pain, nausea, vomiting)

• jaundice or elevated serum aminotransferase (AST, ALT) levels, dark urine, light stool

• Adults usually more symptomatic• Patients are infective while they are shedding the

virus in the stool- usually before the onset of symptoms

• Complete recovery 99% (rarely can be fulminant)

0 1 2 3 4 5 6 7 8 9 10 11 12 13Week

Re

sp

on

se

Clinical illness

ALT

IgM IgG

HAV in stool

Infection

Viremia

EVENTS IN HEPATITIS A VIRUS INFECTION

Hepatitis A Diagnosis

• Detection of anti HAV IgM antibody by an ELISA or Radioimmunoassay test

• Liver enzyme test

PREVENTING HEPATITIS A

• Hygiene (e.g., hand washing)

• Sanitation (e.g., clean water sources)• Immune globulin (pre- and post-exposure)

(older passive vaccination)

• Hepatitis A vaccine (pre-exposure)

Hepatitis A Treatment

• Supportive- no specific role of antiviral therapy

• Lifelong immunity likely after infection or vaccination

HEPATITIS A VACCINES

1st dose at time 0

2nd dose 6-12 months afterwards

Hepatitis A Vaccine

• Vaccine is recommended for the following persons 2 years of age and older: – Travelers to areas with increased

rates of hepatitis A- Persons with chronic liver disease

– Children living in areas with increased rates of hepatitis A

Hep A : Passive Immunization

• Hepatitis A immune globulin can be given up to 2 weeks after an exposure

• Immunity temporary (4-5 months)

• Also given in travelers leaving for endemic area on short notice (ie not enough time for the vaccine to be effective)

Hepatitis B Virus

HBV: Structure• Family : Hepadnaviridae (Hepatitis DNA viruses) • complete virion• 42nm enveloped virus and double-shelled Dane particle

• (consist only of excess surface antigen)• Hepatitis B core antigen (HBcAg)• Hepatitis B e antigen (HBeAg) • Genome consists Circular double stranded DNA • Length of 3200 nucleotides• Virus stable and resist environmental factors

CDC and HI Vand Hepatitis.com, 2002

HBV: Epidemiology

• Worldwide Distribution

• Acute and Chronic infections

1. Center for Disease Control

Geographic Distribution of Chronic HBV Infection

HBsAg Prevalence

8% - High

2-7% - Intermediate

<2% - Low

Hepatitis B Virus

in Various Body Fluids

High Moderate Low

blood semen urineserum vaginal fluid feces

wound exudates saliva sweat

tearsbreast milk

Risk Factors for Acute Hepatitis B

Heterosexual* (41%)

Homosexual Activity (9%)

Household Contact (2%)

Health Care Employment (1%)

Other (1%)Unknown (31%)

InjectingDrug Use

(15%)

HBV Pathogenesis

• Virus enters hepatocytes via blood• Immune response (cytotoxic T cell) responsible for

clinical syndrome• 5 % of adults become chronic carriers (HBsAg> 6

months)• Higher rate of hepatocellular carcinoma in chronic

carriers, • Hepatitis B surface antibody likely confers lifelong

immunity• Hepatitis B e Ag indicates high transmissibility• Hepatitis B e Ab indicates low transmissibility

Hepatitis B - Clinical Features

• Incubation period: Average 60-90 days • Clinical illness (jaundice): less common in young children

• Acute case-fatality rate: 0.5%-1%

• Chronic infection: <5 yrs, 30%-90%

5 yrs, 2%-10% ( More likely in asymptomatic

infections)

• 15 to 25% of chronically infected patients will die from chronic liver disease

Possible Outcomes of HBV InfectionAcute hepatitis B

infection

Chronic HBV infection

3-5% of adult-acquired infections

95% of infant-acquired infections

Cirrhosis

Chronic hepatitis

12-25% in 5 years

Liver failureHepatocellular carcinoma

6-15% in 5 years 20-23% in 5 years

DeathDeath

Acute Hepatitis B Virus Infection with RecoveryTypical Serologic Course

Weeks after Exposure

Titer

Symptoms

HBeAg anti-HBe

Total anti-HBc

IgM anti-HBc anti-HBsHBsAg

0 4 8 12 16 20 24 28 32 36 52 100

Progression to Chronic Hepatitis B Virus Infection

Typical Serologic Course

Weeks after Exposure

Titer

IgM anti-HBc

Total anti-HBc

HBsAg

Acute(6 months)

HBeAg

Chronic(Years)

anti-HBe

0 4 8 12 16 20 24 28 32 36 52 Years

Current Treatment Options for HBV

• Interferon alfa (Intron A)

• Lamivudine (Epivir HBV)

• Adefovir dipivoxil (Hepsera)

• Prevent perinatal HBV transmission (HBs Ag screening of pregnant

women)• Routine vaccination of all infants• Vaccination of children, adolescents,

and adults in high-risk groups

Control of Hepatitis B

Hepatitis B Vaccine

• Infants: several options that depend on status of the mother – If mother HBsAg negative: birth, 1-2m,6-18m– If mother HBsAg positive: vaccine and Hep B immune

globulin within 12 hours of birth, 1-2m, <6m

• Adults– 0,1, 6 months

• Vaccine recommended in– All those aged 0-18– Those at high risk

Hepatitis B High Risk Groups

• Persons with multiple sex partners or diagnosis of a sexually transmitted disease

• Men who have sex with men

• Sex contacts of infected persons

• Injection drug users

• Household contacts of chronically infected persons• Infants born to infected mothers • Infants/children of immigrants from areas with high

rates of HBV infection• Health care and public safety workers• Hemodialysis patients

Hepatitis B: Passive Immunization

• Infants of surface antigen positive mothers

• Exposures to infected blood or infected body fluids in individuals who are unvaccinated, unknown vaccination, or known non-responders.– Ideally within 24 hours– Probably not effective >7days post exposure

منشورات  

نماذج أخرى ● ذاتية سيرة

 تاريخ اإلضافة

الوصف العنوان FID

الم تحميللف

11/7/2008 5:43:56

PM

Papillomavirus

es and Poxviru

ses

فيروسات محاضرة

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الم تحميللف

11/7/2008 5:53:55

PM

Viral Agents

Causing Gastroenteritis

فيروسات محاضرة

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الم تحميللف

12/26/2008

5:15:12 PM

BIOSAFETY-01

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12/26/2008

5:39:23 PM

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13537

الملفات

www.kau.edu.sa/ojiffri