Current status of infection-related gastrointestinal and hepatobiliary diseases in Thailand.

The objective of this overview is to assess the present situation with regards to gastrointestinal and hepatobiliary diseases prevailing in Thailand. In that context, special emphasis has been put on those forms of viral hepatitis prevalent in the region, namely, hepatitis A the frequency of which has undergone a change from hyper- to hypoendemic with a resulting decline in naturally acquired immunity; hepatitis B with its tendency to cause chronic liver disease mainly due to asymptomatic infections during early childhood and the impact of mass vaccination programs on its endemicity; hepatitis C which can also lead to chronicity; hepatitis D solely found as a coinfection with hepatitis B; hepatitis E acute cases of which can sporadically be found; hepatitis G encountered in healthy subjects at a prevalence similar to that seen in patients with chronic liver disease and rather more prevalent among people at risk for contracting blood borne agents; finally the novel hepatitis TT virus with a distribution comparable to that of hepatitis G virus and a similarly unclear role as to the etiology of serious liver disease. Particularly in connection with hepatitis B we have examined the situation regarding hepatocellular carcinoma which represents one of the most common malignancies among the Thai population. Cholangiocarcinoma caused by the liver fluke Opisthorchis viverrini is the most common form of liver cancer in the northeastern part of Thailand where an estimated 70% of the population are infested with the parasite. Peptic ulcer caused by Helicobacter pylori constitutes another common gastrointestinal affliction with the overall prevalence of antibodies to the agent amounting to 63 to 74% in patients exhibiting gastroduodenal symptoms. The final part of the paper deals with HIV-related gastrointestinal and liver disease and with amebic and pyogenic liver abscesses.