Transfusion Related Hepatitis A and B

• before 1984, used to screen blood for Hepatitis B and syphilis
• Adding donor interviews and doing volunteer only donations, plus better testing methods, have greatly reduced the risks of acquiring infections from blood transfusions
• a large percentage of transfusion transmitted complications have a viral etiology
• viruses are intracellular organisms, which use the host to reproduce
• the transmission of viruses can be associated with cellular components or plasma
• any blood product made from pooled plasma is more likely to transmit viruses
• the hepatitis viruses attack the liver
• there are 6 classes of primary hepatitis viruses (A-G), but the ones we are concerned with are A, B, C
• secondary hepatitis viruses involve the liver secondary to another infection (EBV, CMV, etc)
• all hepatitis viruses can be transmitted through blood products
• only products that are specially treated to deactivate virus can viruses not transmit (e.g. plasma protein fraction)
• the risk of hepatitis viral transmission via blood products is greatly reduced: HCV transmission is 1 in 1.1 million units; HBV is about 1 in 1.2 million units
• the first hepatitis A epidemic was in the 17th century; it was discovered that it is shed through the stool
• hepatitis A is a small, RNA, simple, nonenveloped virus with a nucleocapsid
• 40-45% of adults have evidence of prior exposure to hepatitis A, usually follows fecal-oral route
• hepatitis A is transmitted via contaminated food and water; or person-to-person, especially when poor hygein is involved (day-care centers are prone to outbreaks)
• risks of hep A: living in areas with poor sanitation, travel to endemic areas, people in prison, IV drug use
• hepatitis A is rarely spread via transfusion because no chronic carrier state occurs
• for hepatitis A transmission via blood products, donor would have to be in the 2-6 week incubation phase
• many adults who would receive transfusion from donor with hepatitis A would have resistance due to prior exposure
• there isn't a higher transmission rate of hepatitis A in patients who have had multiple transfusions
• incubation for HAV is 14-45 days
• viral replication of Hep A occurs in the liver, the virus is then excreted through the biliary system into the feces
• in Hep A, see brief viremia (can be transmitted in transfusions in this stage of the disease)
• symptoms of Hep A: nausea, vomiting, loss of appetite, malaise, diarrhea; jaundice is often present
• we can use hepatitis A markers to ID current or past infections
• if HAV is suspected, test for IgM antibodies to the virus
• If there is no IgM, but you find IgG, indicates old infection
• routine antibody screenings for HAV is not done
• donor interview questions are designed to pick up symptoms that may indicate HAV infection
• if HAV is discovered after the fact, can give recipient serum immune globulin which will decrease symptoms
• Travelers to endemic places should get a HAV vaccination
• HAV is seen mostly in unvaccinated, young children in resource-limited countries
• hepatitis B was found as an antigen in Australian aborigines.  It was called the Australian antigen (Au), now it is known as Hepatitis B surface antigen (HBsAg)
• •HBV can also be found in Peking ducks, woodchucks, and some ground squirrels
• HBV is a double-stranded DNA virus
• HBV's inner core contains a partially double-stranded DNA surrounded by a surface coat composed of lipid and protein
• also in core of HBV, along with the DNA is an enzyme -- DNA polymerase
• four genes present in HBV DNA: S, C, P, X
• S gene: codes for the surface antigen HBsAg