Human cystic echinococcosis transmission dynamics in Iran, 1997-2040: modeling control strategies for public health...

Cystic echinococcosis (CE) remains a significant public health burden in Iran, with humans serving as accidental dead-end hosts. This study assesses historical CE prevalence trends and projects future human CE burden under targeted intervention scenarios using mathematical modeling. We developed a dynamic Susceptible-Exposed-Inected-Recovered (SEIR) transmission model of CE in Iran, calibrated to historical human prevalence data (1997-2023). Univariate and bivariate sensitivity analyses were conducted to evaluate the influence of key parameters. Model projections to 2040 evaluated four intervention scenarios: a baseline scenario and three alternatives, targeting reductions in exposure rates and increases in case detection rates. Human CE prevalence declined from 3.90% (1997) to 2.20% (2023), representing a 43.49% reduction. Projected trends indicate further decline to 1.37% by 2040 (37.79% reduction from 2023). The 40% exposure reduction scenario achieved the lowest prevalence (1.16% in 2040; 47.31% reduction), while the combined 20% exposure reduction plus 20% detection rate increase scenario yielded 1.27% (42.54% reduction). Crucially, enhanced detection rate reduced long-term prevalence by shortening time-to-diagnosis (time from infection to diagnosis), accelerating case resolution without altering transmission dynamics. To accelerate Iran's successful CE control program toward timely elimination, a decisive strategy to reduce transmission at its source is paramount. Our modeling identifies a 40% reduction in the exposure rate as the most effective intervention to minimize prevalence by 2040. Enhancing early detection provides synergistic benefits, but targeted veterinary and environmental control must be the priority for a rapid and equitable outcome.