VIRAL HEPATITIS (PowerPoint)
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DEFINITION • An acute or sub-acute, Febrile, Infectious diseases characterized by infectious diseases characterised by nausea anorexia, dark coloured urine and yellowners of sclera or skin caused by a group or skin caused by a group of viruses. TYPES • At least six different types of viruses have been isolated – Hepatitis ‘A’ Virus (HAV) – Hepatitis ‘B’ Virus (HBV) – Hepatitis ‘c’ Virus (HCV) – Hepatitis ‘D’ Virus (HDV) – Hepatitis ‘E’ Virus (HEV) – Hepatitis Non A,Non B Non C Virus (HNANBNC) Distribution • World vide HAV infection is more common in developing countries with poor sanitary conditions. HBV is more common in some parts of Europe as well. HEPATITIS ‘A’ • Synonym – Infectious Hepatitis • Agent – Entero virus type > 2 of picornaviridas family multiplies only in liver cells fairly resistant to heat and chemicals. With stands temp of 60C for 1 hour, and chlorination at usual doses of domestic water supply. Readily destroyed by formoline, boiling for 5 minutes and autoclaving. Reservoir of infection • Human cases are the only reservoir. They may be Inapparent, mild or severe cases all shedding the virus in faeces. Host Factors • Age Common in all ages but in Children mild and inapparent infection is more common. • Sex Equal among both saxes. Immunity : One attack confers lifelong immunity – second attack reported in 5% cases. In India 90% of population is sero conuerted by the age of 10 years most by through subclinical infection. Environmental Factors • Season – – Occurs throughout the year but out breaks are more common in rainy season. – Poor sanitation – Over Crowding Mode of Transmission • Faeco oral Route • Contamination of water • Contamination of food Incubation period – 15 to 45 days Diagnosis – - Demonstration of virus particles in faeces - Rise in anti HAV titre - Detection of IgM antibody to HAV in patients serum Prevention and Control • Control of Reservoir • Control of Transmission • Protection of susceptible population – Human immunoglobulin 0.02 ml/kg for family contacts (3.2 mg/kg) – Vaccine under trials. Hepatitis ‘B’ • Synonym – Serum Hepatitis • Agent – Discovered by blumbers in 1963. Complex double shelled DNA virus of 42 mm (Dane particle) also occurs in 22 mm spherical forms and tubular forms of varying length of the three forms only dane particle is infective. • The virus has three distinct antigens. – Surface Antigen HBsAg – Core Antigen HBcAg – ‘e’ Antigen HBeAg Virus is fairly resistant to heat and chemicals can survive 60oC for 10 hours in plasma. Readily destroyed by sodium hypochlorite and boiling for 5 minutes Reservoir of Infection • Human cases and carriers Period of communication – 1 month Before onset of Jaundice – During acute phase of disease Untill disappearance of HBsAg Age • In countries where infection is uncommon – sero conversion occurs in age group 2040 in countries where infection is common – perinatal transmission in common High Risk Groups - Recipients of blood transfusion - Health Care personnel - IV Drug abusers - Prostitutes and Homosexuals Modes of Transmission • Paren teral Route • Perinatal Transmission • Sexual Transmission • Blood sucking Arthropodes? • Incubation period – 45 to 180 days Median Incubation period – 100 days Prevention and Control • Hepatitis ‘B’ Vaccine Plasma Derived – Formoline inactivated sub unit vaccine containing 20 mgm of HBsAg in Alum adjuvant Dose 1 ml at 0,1 & 6 months booster dose – 3-5 years RDNA – Yeast derived vaccine Hepatitis B Immunoglobulin • • • • Passive immunity on acute Exposure 0.05 – 0.07 ml / kg Two doses to be given - Screening of blood donors - Autoclaving of syringes and needles - Care and Education of Carriers Hepatitis ‘C’ • It is a RNA containing Flavi virus. Human seem to be the sole source of infection the mode of transmission is throug inoculation of blood and blood products. IV drug abusers are at increased risk of getting the infection. Sexual and vertical transmission may occur but is not very common current laboratory diagnosis depends on identifying antibodies to several viral antigens. Hepatitis ‘D’ • Hepatitis ‘D’ Virus is a RNA Defective virus which has no independent existence. It requires HBV for replication and has the same mode of spread as HBV.