Transmission of Hepatitis Viruses

Hepatitis A virus (HAV) is shed in the feces, and peak titers occur during the 2 weeks before and 1 week after onset of illness [1]. Virus is also present in serum and saliva during this period, although in concentrations several orders of magnitude less [2]. Consequently, the most common mode of transmission is fecal-oral, with the virus being transmitted from person to person or by contaminated food or water [3]. On the basis of cases of hepatitis A reported in 1992 to the Centers for Disease Control and Prevention (CDC), the most frequently reported risk factor was household or sexual contact with a person with hepatitis (24%), followed by day-care attendance or employment (15%), recent international travel (6%), and association with a suspected food- or water-borne outbreak (5%). Many persons with hepatitis A do not identify risk factors; their source of infection may be other infected persons who are asymptomatic.

Because of the viremic phase during HAV infection, transfusion-related hepatitis A occurs occasionally. The source of infection is usually a blood donor who is incubating the virus at the time of donation. Predonation interviews regarding hepatitis symptoms as well as screening of blood donations for alanine aminotransferase elevations are important safeguards for preventing blood-borne HAV transmission. Blood-borne HAV transmission to neonates or other patients has resulted in nosocomial hepatitis A outbreaks among hospital personnel.

The investigation of HAV transmission to hemophiliacs receiving contaminated factor VIII units, described in this issue of the Annals [4], along with other such outbreaks in Europe, represents further examples of blood-borne HAV transmission. Contamination presumably occurred from plasma donors who were incubating HAV at the time of donation and was substantial enough that the virus was purified along with factor VIII during the preparation process; the solvent-detergent step used in …