Hepatitis Viruses (H.K. (8) PDF)

HEPATITIS VIRUSES Helen Kalandarishvili UG  HEPATITIS VIRUSES Hepatitis is a general term meaning inflammation...

HEPATITIS VIRUSES Helen Kalandarishvili UG  HEPATITIS VIRUSES Hepatitis is a general term meaning inflammation of the liver. Thus it is a systemic disease mainly involving a liver Hepatitis A Hepatitis B Hepatitis C Hepatitis D Hepatitis E hepatitis delta serum hepatitis agent is a defective virus, similar to a viroid and can only propagate in the presence of the infectious common cause of hepatitis B virus. hepatitis posttransfusion hepatitis agent of enterically transmitted hepatitis. Other viruses - Epstein-Barr virus (the cause of infectious mononucleosis), Cytomegalovirus, and Yellow fever virus - infect the liver but also infect other sites in the body and therefore are not exclusively hepatitis viruses.  HEPATITIS VIRUSES Genome Virus Envelope Family, genus Genome size (Kb) 7,5 Positive sense Picornaviridea, HAV RNA (+), Single - Hrpatovirus stranded, Linear 3,2 Partially double HBV DNA + Hepadnavididae stranded, Circular 9,6 Positive sense Flavivididae, HCV RNA (+), Single + Hepacivirus stranded, Linear 1,7 Negative Sense Unclassified HDV RNA (-), single stranded, + (viroid); Delta Virus Circular  HEPATITIS VIRUSES Source of Route of Chronic Virus Prevention virus transmission infection pre/post- Exposure HAV feces fecal-oral No immunization blood/blood-derived Percutaneous pre/post- Exposure HBV Yes body fluids permucosal immunization blood donor blood/blood-derived Percutaneous screening; HCV Yes body fluids permucosal risk behavior modification pre/post- Exposure blood/blood-derived Percutaneous immunization, risk HDV Yes body fluids permucosal behavior modification  HEPATITIS A Picornaviridae  picornavirus genus Hepatovirus  27-32-nm spherical particle with cubic symmetry,  Linear single-stranded RNA (+), genome size - 7.5 kb.  Non enveloped, acid and heat stabile  Only one serotype is known  No antigenic cross-reactivity with HBV or with the other hepatitis viruses. Electron micrograph of the Hepatitis A virus (HAV) HEPATITIS A The virus replicates in the cytoplasm The virion contains three major structural proteins and possesses only a single immunodominant neutralization site. HEPATITIS A Close personal contact (e.g., household contact, sex contact, child day care centers)  HAV is widespread throughout the world. Contaminated food, water (e.g., infected food handlers, raw shellfish)  Humans are the reservoir for HAV Blood exposure (rare)  The mode of transmission - fecal - oral route (e.g., injecting drug use, transfusion)  The appearance of hepatitis in camps or institutions is often an indication of poor sanitation and poor personal hygiene.  HAV is seldom transmitted by the use of contaminated needles and syringes or through the administration of blood.  HAV can be detected in the liver, stool, bile, and blood of naturally infected humans. HEPATITIS Propertie A s HAV is stable to treatment ( 20% ether, acids with pH 1.0 for 2 hours), and heat (60 °C for HAV1 hour) HAV infectivity can be preserved for at least 1 month after being The virus is destroyed by: dried and stored at 25 °C or for  autoclaving (121 °C for 20 min),  boiling in water (5 min), years at -20 °C.  dry heat (180 °C for 1 hr),  UV irradiation (1 min at 1.1 watts),  treatment with chlorine (10–15 ppm 30 min). eating food to > 85 °C for 1 min and disinfecting surfaces with sodium hypochlorite are necessary to inactivate HAV. HEPATITIS A  Disease is most often manifest in children with the highest rates between 5 and 14 years of age.  The incubation period is from 15 up to 50 days.  Illness will start with the rise of temperature, vomiting, and between 5-7 days with appearance of jaundice.  Stool specimens may be infectious for up to 2 weeks before to 2 weeks after onset of jaundice.  Hepatitis A infection can result  Asymptomatic (anicteric) disease ✔ Children under 6 years of age, > 90% ✔ Children from 6-14 years old, 40-50%  Symptomatic (icteric) disease ✔ Adults and children over 14, 70-80% Complete recovery and the development of natural immunity to reinfection ultimately occur in all infected individuals. HEPATITIS Clinical Features A Incubation period: Average 30 days Range 15-50 days Jaundice by age group: