Serological survey of viral hepatitis A, B, and C at Thai Central Region and Bangkok: a population base study.

Hepatitis A, B, and C are important viral hepatitis infections in the Thai population. Hepatitis B vaccination was included in the Thai Expanded Program on Immunization (EPI) 10 years ago. In addition, the seroprevalence of hepatitis A has significantly changed in the last two decades. This study was done to evaluate current risk groups for hepatitis A and B infections and identify the magnitude of hepatitis C infection in the general population of Bangkok and six provinces in the Central Region of Thailand, during the period October 2000 to January 2002. This study revealed that the prevalence of anti-HAV in people younger than 25 years was low but very high in people older than 25 years. The prevalence of anti-HAV was 1.95% in Bangkok and 12.7% in other provinces in people younger than 25 years (p<0.001) while 90.9% in Bangkok and 88.2% in other provinces among people older than 25 years. Therefore, people who are older than 25 years should have a blood test for anti-HAV before getting a hepatitis A vaccination. Approximately 80% of people who are not covered by hepatitis B vaccination from EPI are at risk of hepatitis B infection and its complications. This group of people should receive hepatitis B vaccination. For hepatitis C, the prevalence is lower than 2% across age groups and areas. Therefore, current good primary prevention via blood donor screening and health education must be maintained.