HEPATITIS A VIRUS – HAV (Micro made easy)

• General: RNA virus, has capsid, it is in the family picornaviridae and is transmitted by faecal-oral route (ingestion of contaminated water/food).
• Epidemiology / At risk individuals: HAVe you washed your hands? Persons at risk are: day care centres, travellers + military personnel, sewerage workers, homosexuals, drug users etc.
• Clinical features: Incubation period is 30 days (15-40 day range), the younger the patient  the less chance of developing jaundice. Normal course is: Flue like symptoms ≫ liver function tests abnormal ≫ jaundice ≫ acute hepatitis. Hepatitis A infection does not cause death usually, but complications include: fulminant hepatitis, cholestatic hepatitis, relapsing hepatitis.
• Serology: Refer to graph in lecture notes. The capsid of the virus is antigenic. A serology test finding anti-HAV IgM means active infection (lasts for about 4 months). If you find anti-HAV IgG, it means old infection (lasts a lifetime) ≫ hence is protective against future infections. Look at Fig 24-4 pp 183. Remember these serology markers are only evident after incubation period.
• Prevention/Treatment: There is two major treatment options: 1) vaccine, 2) immune globulin. Both of these should be administered to persons who are at risks groups (i.e.: travellers, military personnel, homosexuals, drug users, chronic liver disease). If a person has been exposed, then administering immune globulin (within 14 days) will reduce severity of infection but will NOT cause infection to go away.

Category: Microbiology Notes