HAV* is transmitted primarily by unsanitary food and water (frequently found in developing countries), or by direct contact with an infected person. It is non-chronic and relatively mild, though symptoms can include jaundice, fatigue, nausea, and fever. Vaccines are available.
HBV is transmitted by bodily-fluids and is far more serious. Chronic liver disease caused by HBV results in death in 15-25% of chronically infected persons. Vaccines are available and are highly recommended.
HCV is perhaps the most dangerous of the hepatitis viruses. Like HBV, it is transmitted by bodily-fluids. It causes severe liver damage in 70% of chronically infected persons; there is no vaccine available; and 80% of infected persons have no symptoms or signs of the disease ? so not only are they at risk, but they can pass it to others unknowingly. Those at particular risk and for whom testing is advised include:
? I.V. drug users ? most infections are due to illegal injection drug use
? Blood transfusion recipients before 1992 (prior to donor screening)
? People with undiagnosed liver problems
? Infants born to infected mothers
? HDV is similar to HBV, and only occurs in its presence, so vaccination-protection for HDV is, for practical purposes, available.
? HEV is relatively mild and non-chronic; it produces symptoms similar to HAV and is transmitted similarly. However, no vaccine is available.
? HFV and HGV are newly identified; their connection with liver disease remains controversial.
*Hepatitis viruses are typically identified by letters, e.g. HAV for Hepatitis A Virus. Virus information is provided by the Center for Disease Control.