Abstract
<title>Abstract</title> <p> Background Ningde City, Fujian Province, China, has the highest reported prevalence of human T-cell lymphotropic virus (HTLV) infection in the country. Nevertheless, epidemiological data on HTLV infection and the screening performance of enzyme-linked immunosorbent assay (ELISA) in general hospital-based populations in this region remain scarce. Methods A total of 11,788 samples were collected from outpatients, inpatients, and physical examination (PE) participants at Ningde Municipal Hospital between 2019 and 2024. ELISA was used for primary screening. All 153 ELISA-reactive samples and a preferentially selected subset of 487 ELISA-non-reactive samples (prioritizing those with higher S/CO ratios) subsequently underwent confirmatory real-time quantitative PCR. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ELISA were calculated using PCR as the reference standard. Binary logistic regression was performed to identify factors associated with HTLV seropositivity. Results The overall ELISA initial reactive rate was 1.30% (153/11,788). The reactive rate among outpatients and inpatients (1.60%) was significantly higher than that among PE participants (0.46%) <italic>(P</italic> < 0.001). Female sex, older age, and outpatient/inpatient status were independently associated with seropositivity. The overall sensitivity and specificity of ELISA were 91.49% and 95.19%, respectively. ROC analysis identified an optimal cut-off value of S/CO = 0.3164, yielding an AUC of 0.9642. Conclusions HTLV infection prevalence is relatively high in Ningde, particularly among clinical patients. Although ELISA demonstrated acceptable overall screening performance—though true sensitivity may be marginally underestimated due to the verification strategy employed—subgroup differences in diagnostic accuracy underscore the need for PCR confirmation and population-specific cut-off optimization, especially in high-endemic settings. </p>