Helicobacter pylori (H. pylori) infection is a major cause of gastrointestinal diseases. Although its seroprevalence in Korea has been continuously declining, it remains high at over 40%. This study aims to estimate the age- and time-specific seroprevalence in Korea by incorporating the force of infection (FOI) and immune waning into a mathematical model.
We analyzed Korean H. pylori survey data (1998, 2005, 2011, and 2015) from individuals aged 16 and older. Seroprevalence was modeled using the McKendrick partial differential equation: $\\left(\\frac{\\partial}{\\partial a} + \\frac{\\partial}{\\partial t}\\right)s(a,t)=-\\\\lambda(a,t)s(a,t)$, where $\\lambda(a,t)$ is the FOI and $s(a,t)$ is the fraction of susceptible individuals. The FOI was modeled to decrease exponentially after a specific year, and immune waning was integrated as a probability distribution. Model parameters were estimated using Maximum Likelihood Estimation and Markov Chain Monte Carlo methods.
The estimation results indicated that the FOI in Korea began to decline in 1984, with a baseline FOI of 0.038 per year prior to 1984. Consequently, recent birth cohorts exhibit significantly lower seroprevalence compared to older cohorts at the same age. These findings demonstrate that hygiene and socioeconomic improvements have effectively reduced H. pylori transmission, and this model can be utilized to predict future declines in seroprevalence.