While the decline of Toxoplasma gondii IgG (TpIgG) titers over time has been documented in HIV-negative populations, the long-term trajectory of TpIgG in people with HIV (PWH) receiving antiretroviral therapy (ART) remains poorly understood. Moreover, potential associations with ART and CD4-positive lymphocyte count have not yet been clarified.

This single-center, cross-sectional study was conducted between 2021 and 2022 at Jikei University Hospital. TpIgG titers were measured by ELISA in PWH who visited the hospital during the study period and were compared with results from our previous cross-sectional survey performed in 2015–2016. Clinical information, including CD4 profiles and duration of ART, was extracted from medical records to evaluate correlations with longitudinal changes in TpIgG titers. In addition, historical TpIgG measurements recorded outside of the 2015–2016 and 2021–2022 surveys were retrieved from medical records to provide extended longitudinal observations.

Among 416 PWH enrolled, 7.2 % (30/416) tested positive for TpIgG in 2021–2022, with no significant demographic differences between TpIgG-positive and -negative groups. In 22 participants with paired measurements from 2015 to 2016 and 2021–2022, TpIgG titers showed a significant decline over time (p = 0.00593). While antibody trajectories were generally downward, correlation analyses revealed no significant associations between TpIgG changes and nadir CD4 count, CD4 recovery, or ART duration.

TpIgG titers significantly declined during long-term ART, with no clear correlation to immunological parameters. Continued monitoring and further research are warranted to clarify the clinical implications of these antibody dynamics.

Toxoplasma gondii

HIV

Longitudinal antibody trend

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