Serological evidence of hepatitis A, B, and C virus infection in older adults in Khon Kaen, Thailand and the estimated rates of chronic hepatitis B and C virus infection in Thais, 2017

Abstract

Hepatitis A (HAV), hepatitis B (HBV), and hepatitis C (HCV) viruses are hepatotropic viruses responsible for acute/chronic hepatitis associated with liver failure, cirrhosis, and hepatocellular carcinoma. Due to the limited data on the prevalence of hepatitis in the older population in Thailand, this study aimed to evaluate the seroprevalence of these viruses in elderly Thais. Using an automated immunoassay, serum samples from individuals older than 60 years of age in Chum Phae district of Khon Kaen province in northeast Thailand were analyzed for anti-HAV (n = 93), HBV markers (n = 460, HBsAg, anti-HBs, and anti-HBc), and anti-HCV (n = 460). Samples were classified into five age groups (61-65, 66-70, 71-75, 76-80, and >80 years). The overall seroprevalence of anti-HAV, HBsAg, anti-HBc, anti-HBs, and anti-HCV was 98.9%, 4.6%, 51.5%, 32.4%, and 1.3%, respectively. When samples were stratified into three groups representing three generations (children/young adults aged 6 months-30 years and middle-aged adults between 31-60 years old from a previous survey, and older adults aged >60 years from the current study), the highest levels of anti-HAV and anti-HBc were found in older adults. Children/young adults had the lowest levels of HBsAg and anti-HCV, and the highest level of anti-HBs. These findings are consistent with the integration of HBV vaccination into the Expanded Program on Immunization (EPI) in 1992 and coincide with increased awareness of blood-borne viral transmission in Thailand. Extrapolating from our data, the estimated numbers of cases of chronic HBV and HCV infection in Thailand in 2017 were 2.2 and 0.79 million, respectively. Thus, effective treatments for viral hepatitis B and C for middle-aged and elderly Thais are needed. This seroprevalence survey could be used to help formulate policies and possible guidelines for treatment and prevention in specific age groups, which is recommended to facilitate the elimination of viral hepatitis by 2030.

Keywords: Older adult; Thailand; Viral hepatitis.

Figure 1. Seroprevalence of anti-HAV, HBsAg, anti-HBs, anti-HBc, and anti-HCV in this study.

The five age groups (61–65, 66–70, 71–75, 76–80, and >80 years old) are shown on the x-axis. The proportions of individuals positive for (A) anti-HAV, (B) HBsAg, (C) anti-HBc, (D) anti-HBs, and (E) anti-HCV are presented on the y-axis. A total of 460 individuals were screened for HBV markers (HBsAg, anti-HBc, and anti-HBs) and for anti-HCV, while 93 individuals were tested for anti-HAV.

Figure 2. Seroprevalence of anti-HBs and the geometric mean titers (GMTs) in older Thai adults.

(A) Anti-HBs levels are indicated as follows: <1 mIU/ml (white), 1 –<10 mIU/ml (light blue), 10 –<100 mIU/ml (blue), 100 –<1,000 mIU/ml (navy), and ≥1,000 mIU/ml (black). Numbers associated with the bar graphs represent percent seroprevalence (y-axis). (B) The GMTs derived from anti-HBs ≥1 mIU/ml are in log₁₀ scale (y-axis). The x-axis indicates age groups.

Figure 3. Seroprevalence against HAV (anti-HAV), HBV (HBsAg, anti-HBc, anti-HBs), and HCV (anti-HCV) in different age groups.

Thais of different age groups (6 months to 30 years, 31–60 years, and >60 years old, denoted in x-axis) were evaluated for (A) anti-HAV, (B) HBsAg, (C) anti-HBc, (D) anti-HBs, and (E) anti-HCV. Population is shown on the y-axis. The 2014 study involved age groups 6 month—60 years old, while the 2017 study involved >60 years old. Average serological values are noted (red squares). Asterisk denotes seropositivity rate of statistical significance between middle-aged and older adults (p < 0.05).

Figure 4. Estimated numbers of males and females positive for anti-HAV, HBsAg, anti-HBc, anti-HBs, and anti-HCV aged <5, 5–10, 11–20, 21–30, 31–40, 41–50, 51–60 (2014 data) and 61–70, 71–80 and >80 (2017 data).

The y-axis represents the ten age groups in the Thai population. The x-axis represents the number (×10⁶) of males and females in Thailand, as indicated by the blue and pink bars, respectively. The navy blue and red bars indicate the number of males and females, respectively, who were positive for anti-HAV (A), HBsAg (B), anti-HBc (C), anti-HBs (D), and anti-HCV (E).