Viral hepatitis is an important group of infectious disease in Hong Kong. It is now known to be caused by at least five viral agents. These etiologically separate and identified forms are hepatitis A, hepatitis B, hepatitis C, hepatitis D (delta agent), and hepatitis E. They are in turn caused by hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), hepatitis E (HEV) and hepatitis G virus (HGV) respectively. Having been identified as recent as 1995, HGV is not properly studied in the local setting yet. However, we are hopeful that more information will be available on this virus in the next issue of the report.

In Hong Kong, voluntary reporting of viral hepatitis was started in 1966 by the then Medical and Health Department. It did not become notifiable until 1974. From 1988 onwards, the notification system has been expanded with the breakdown into hepatitis A, hepatitis B, non-A non-B hepatitis and unclassified infection. However, the notification of viral hepatitis is limited by

1. under-reporting,
2. lack of separate data on hepatitis C, D, E and G, and
3. difficulties in distinguishing between acute, chronic and acute-on-chronic infection arising from hepatitis B and C.

In view of the limitations, the Scientific Working Group on Viral Hepatitis Prevention favored the establishment of a local serosurveillance system for monitoring viral hepatitis epidemiology, a centralized effort to collect data, monitor and analyze the epidemiologic pattern of viral hepatitis in Hong Kong. This proposal was endorsed by the Working Group at its seventh meeting on 15 May 1995.

This report reviews the seroepidemiology of viral hepatitis in Hong Kong and assesses the temporal changes which have been brought updated as of the end of December 1996.