When compared with Thailand, the seroprevalence of hepatitis A virus
(HAV) is extremely high among its neighbouring countries. To
investigate the seroprevalence of HAV among the Thai people residing in
the border area between Thailand and Myanmar, 308 residents in Umphang,
Maesod district, Tak, were recruited. Sera were tested for HAV IgG
antibodies by enzyme-linked immunosorbent assay. The overall
seroprevalence among the Thai people residing in the border area of
Thailand was significantly higher than that among the general Thai
population (71% vs 27% respectively, p<0.05). As asymptomatic or
mild HAV infection typically occurs in children, the Thai people
residing in the border area may receive little benefit from universal
HAV vaccination. Lower protective antibodies against HAV, along with
the exclusion of HAV vaccine from the Expanded Programme on
Immunization, potentially increase the susceptibility to HAV among the
general Thai population and may lead to more future outbreaks if HAV is
introduced from the border areas. The findings suggest that HAV
vaccines should be recommended to travellers before their journey to
the border between Thailand and Myanmar where HAV is endemic