Declining Trend of Hepatitis A Seroepidemiology in Association with Improved Public Health and Economic Status of Thailand

Abstract

Hepatitis A virus (HAV) is transmitted via the fecal-oral route from contaminated food or water. As part of the most recent survey of viral hepatitis burden in Thailand, we analyzed the current seroprevalence of HAV in the country and compared with data dating back to 1971. From March to October, 2014, a total of 4,260 individuals between one month and 71 years of age from different geographical regions (North = 961; Central = 1,125; Northeast = 1,109; South = 1,065) were screened for anti-HAV IgG antibody using an automated chemiluminescent microparticle immunoassay. Overall, 34.53% (1,471/4,260) possessed anti-HAV IgG antibody, and the age-standardized seroprevalence was 48.6%. Seroprevalence rates were 27.3% (North), 30.8% (Central), 33.8% (Northeast) and 45.8% (South) and were markedly lower than in the past studies especially among younger age groups. The overall trend showed an increase in the age by which 50% of the population were anti-HAV IgG antibody: 4.48 years (1971–1972), 6 (1976), 12.49 (1990), 36.02 (2004) and 42.03 (2014).This suggests that Thailand is transitioning from low to very low HAV endemicity. Lower prevalence of HAV correlated with improved healthcare system as measured by decreased infant mortality rate and improved national economy based on increased GDP per capita. The aging HAV immuno-naïve population may be rendered susceptible to potential HAV outbreaks similar to those in industrialized countries and may benefit from targeted vaccination of high-risk groups.

Changes in hepatitis A virus (HAV) seroprevalence in medical students in Bangkok, Thailand, from 1981 to 2016

“…This dynamic change confirms that over time, HAV enmity in Thailand has shifted from low to very low due to the improvement of sanitation and national economy [10]. The present study demonstrated the overall high HAV seropositivity in medical students in this era resembled that of the data in 1982 [1] when the vaccine was not available.…”

Changes in seroprevalence of hepatitis A after the implementation of universal childhood vaccination in Shandong Province, China: A comparison between 2006 and 2014

“…The reduction in seroprevalence among subjects 15-29 years of age, as seen particularly in those 20-29 years of age, might be attributable in part to a decline in the circulation of HAV, because vaccination of children ultimately results in less exposure to the virus. However, it should be mentioned that natural infection has been declining with the rapid improvement in sanitation in recent years (Sa-nguanmoo et al, 2016;Franco et al, 2012), which will also have contributed to a decrease in anti-HAV seroprevalence in addition to the effects of vaccination. Nevertheless, the decline in seroprevalence will result in a higher proportion of population susceptible to HAV and should be of concern.…”

Changing sero-epidemiology of hepatitis A in Asia Pacific countries: A systematic review

“…Changing government policy and increased trade and foreign investment have helped several countries such as Thailand, Singapore, Korea, Japan, and China to grow their economies during the last quarter century. This growth has been associated with an increase in healthcare expenditure and improvements in sanitation and hygiene levels, and increasing age at first HAV exposure (Sa-nguanmoo et al, 2016;Kiyohara et al, 2007). Korea is a good example.…”