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
(1رقم )6370
الم تحميللف
11/7/2008 5:53:55
PM
Viral Agents
Causing Gastroenteritis
فيروسات محاضرة
(2رقم )6373
الم تحميللف
12/26/2008
5:15:12 PM
BIOSAFETY-01
BIOSAFETY-01
13534
الم تحميللف
12/26/2008
5:39:23 PM
BIOSAFETY-02
BIOSAFETY-02
13537
الملفات
www.kau.edu.sa/ojiffri