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Presented by:Group C PCL II 1/12/2014GROUP C;PCL II1.

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Presentation on theme: "Presented by:Group C PCL II 1/12/2014GROUP C;PCL II1."— Presentation transcript:

1 Presented by:Group C PCL II 1/12/2014GROUP C;PCL II1


3 Hepatitis A Virus Introduction Naked RNA virus Related to enteroviruses, formerly known as enterovirus 72, now put in its actual family:picornavirus One stable serotype only Difficult to grow in cell culture: primary marmoset cell culture and also in vivo in chimpanzees and marmosets. 1/12/2014GROUP C;PCL II3

4 Hepatitis A Virus 1/12/2014GROUP C;PCL II4

5 1/12/2014GROUP C;PCL II5 Source of virus fecesblood/ blood-derived body fluids blood/ blood-derived body fluids blood/ blood-derived body fluids feces Route of transmission fecal-oralpercutaneous permucosal percutaneous permucosal percutaneous permucosal fecal-oral Chronic infection noyes no Preventionpre/post- exposure immunization pre/post- exposure immunization blood donor screening; risk behavior modification pre/post- exposure immunization; risk behavior modification ensure safe drinking water Introduction contd ABCDE

6 HAV biology HAV is one kind of picornavirus and used to be classified as enterovirus type72, but recently, it is considered to be classified as heparnavirus Hepatitis A virion is a naked spherical particle, diameter 27nm Consists of a genome of linear, single-stranded RNA, 7.5kb. The genome may be divided into 3 coding region: P1 region (encoding structural protein), P2 and P3 regions (encoding non-structure protein) During acute stage of infection, HAV can be found in blood and feces of infected human and primates Marmoset and chimpanzee are susceptible animals 1/12/2014GROUP C;PCL II6


8 HAV on EM 1/12/2014GROUP C;PCL II8

9 HAV biology HAV can not cause cytopathy, replicate within cytoplasma of hepatocytes and via bile are discharged with feces 7 genotypes, 1, 2, 3, 7 types from human body Only one antigen-antibody system. Anti-HAV IgM is diagnostic evidence of recent infection, IgG is protective antibody. Resistance of HAV: 56°C, 30 min, usually temperature 1 week, dry feces at 25°C 30 days, fresh water, sea water,shellfish or soil for several months. 70% alcohol at 25°C, 3 min, 100°C, 5 min and ultraviolet, 1 min 1/12/2014GROUP C;PCL II9

10 Close personal contact (e.g., household contact, sex contact, child day care centers) Contaminated food, water (e.g., infected food handlers, raw shellfish) Blood exposure (rare) (e.g., injecting drug use, transfusion) 1/12/2014GROUP C;PCL II10 Transmission-Epidemiology

11 Endemicity Disease Rate Peak Age of InfectionTransmission Patterns HighLow to High Early childhood Person to person; outbreaks uncommon ModerateHighLate childhood/ young adults Person to person; food and waterborne outbreaks Low Young adultsPerson to person; food and waterborne outbreaks Very low AdultsTravelers; outbreaks uncommon Global Patterns of Hepatitis A Virus Transmission 1/12/2014GROUP C;PCL II11

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14 pathogenesis HAV invade into human body by mouth and cause viremia. After one week,the HAV reach liver cells replicate within. Then enter intestine with bile and appear in feces. Its believed that damage of liver cells maybe caused by immune response. HAV does not cause cytopathy 1/12/2014GROUP C;PCL II14

15 1/12/2014GROUP C;PCL II15 After HAV replicating and discharging, liver cells damage begin Animal experiment proved that immune complex may attend the pathogenesis of HA: activated T cell secrete γ-INF that promote the representation of HLA- antigen on the liver cells, CTL(cytotoxic T lympocyte)may kill the target cell infected with HAV

16 Step 1: HAV attaches to the basilar surface of the hepatocyte. (HAV demonstrates hepatotropism) The virion binds with its specific glycoprotein receptor. The capsule is internalized through the host cell membrane via clathrin-mediated endocytosis. Step 2:The viral genomic RNA is released into the host cell. Step 4: Reverse transcription of the ssRNA strand occurs. Steps 3,5: The reverse transcribed dsRNA is translated into viral proteins. The proteins are then assembled and packaged into vesicles. Step 6:The vesicles are released at the apical surface of hepatocyte 1/12/2014GROUP C;PCL II16 REPLICATION CYCLE OF HAV

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18 Clinical presentation Prodrome(EARLY STAGE) patients may have mild flulike symptoms of anorexia, nausea and vomiting, fatigue, malaise, low-grade fever (usually < 39.5°C), myalgia, and mild headache 1/12/2014GROUP C;PCL II18

19 Icteric phase In the icteric phase, dark urine appears first (bilirubinuria). Pale stool soon follows, although this is not universal. Jaundice occurs in most (70-85%) adults with acute HAV infection; The degree of icterus also increases with age. 1/12/2014GROUP C;PCL II19

20 Relapsing hepatitis A Relapsing hepatitis A is an uncommon sequela of acute infection, is more common in elderly persons 1/12/2014GROUP C;PCL II20

21 Incubation period:Average 30 days Range days Jaundice by 14 yrs, 70%-80% Complications: Fulminant hepatitis Cholestatic hepatitis Relapsing hepatitis Chronic sequelae:None 1/12/2014GROUP C;PCL II21

22 Laboratory Diagnosis Acute infection is diagnosed by the detection of HAV-IgM in serum by EIA. Past Infection i.e. immunity is determined by the detection of HAV-IgG by EIA. Cell culture – difficult and take up to 4 weeks, not routinely performed Direct Detection – EM, PCR technique. It can detect illness earlier than serology but rarely performed. 1/12/2014GROUP C;PCL II22

23 Fecal HAV Symptoms Hepatitis A Infection Total anti- HAV Titr e ALT IgM anti-HAV Months after exposure Typical Serological Course 1/12/2014GROUP C;PCL II23

24 prevention Control of source of infection Cut off the route of transmission Protection of susceptible population Active immunity Passive immunity 1/12/2014GROUP C;PCL II24

25 Many cases occur in community-wide outbreaks no risk factor identified for most cases highest attack rates in 5-14 year olds children serve as reservoir of infection Persons at increased risk of infection travelers homosexual men injecting drug users 1/12/2014GROUP C;PCL II25 Hepatitis A Vaccination Strategies Epidemiologic Considerations

26 Pre-exposure travelers to intermediate and high HAV-endemic regions Post-exposure (within 14 days) Routine household and other intimate contacts Selected situations institutions (e.g., day care centers) common source exposure (e.g., food prepared by infected food handler) 1/12/2014GROUP C;PCL II26 Prevention - Immune Globulin

27 VaccineAge(years)Dose*Volume(mL) Two-does schedule(mos) HAVRIX§ (EL.U.)0.50, 6–12 >181,440 (EL.U.)1.00, 6–12 VAQTA¶ (U)0.50, 6–18 >1850 (U)1.00, 6–18 * EL.U. = enzyme-linked immunosorbent assay (ELISA) units. U = units. 0 months represents the timing of the initial dose; subsequent numbers represent the months after the initial dose. § Hepatitis A vaccine, inactivated, GlaxoSmithKline Biologicals. This vaccine also is licensed for a 3-dose series in children aged 1–18 years, with 360 EL.U., 0.5-mL doses at 0, 1, and 6–12 months. r ¶ Hepatitis A vaccine, inactivated, Merck & Co., Inc 1/12/2014GROUP C;PCL II27

28 REFERENCES: 1/12/2014GROUP C;PCL II28 Clinical microbiology made ridiculously simple

29 GOD BLESS YOU ALL!!!!!!!!!!!!! 1/12/2014GROUP C;PCL II29

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