Urine detection of Histoplasma antigens among symptomatic people living with HIV (PLWH) in Mato Grosso do Sul, Brazil: A comparative study of EIA and lateral flow assay.

Abstract

Histoplasma spp., thermally dimorphic fungus acquired from environmental exposure, is associated with high mortality in people with advanced HIV disease. Early diagnosis remains challenging because conventional mycological methods have limited sensitivity, reinforcing the importance of urinary antigen detection. We conducted a cross-sectional study between 2022 and 2023 at a tertiary referral hospital in Campo Grande, Mato Grosso do Sul, Brazil, to assess the agreement between two urinary Histoplasma antigen detection platforms and to evaluate Histoplasma antigenuria among symptomatic people living with HIV (PLWH) with suspected disseminated histoplasmosis (DH). During the study period, 241 PLWH underwent urinary Histoplasma antigen testing with both an enzyme immunoassay (EIA; IMMY Clarus® Histoplasma Galactomannan Antigen) and a lateral flow assay (LFA; MiraVista Histoplasma LFA) at our laboratory. Of these, 78 fulfilled the predefined clinical eligibility criteria for suspected DH and were included in the study. Additional immunodiagnostic assays for paracoccidioidomycosis, aspergillosis, and cryptococcosis were also performed. Urinary Histoplasma antigen was detected in 18 patients, corresponding to a frequency of 23.1% (95% confidence interval [CI], 14.6%-34.2%) among symptomatic PLWH with suspected DH. The most frequent clinical manifestations were weight loss (84.6%), fever (80.8%), and cough (71.8%). Coinfections were common, and the case fatality rate among antigen-positive patients was 27.8% (5/18; 95% CI, 10.7-53.6). Inter-assay agreement between EIA and LFA was high (93.6%). Our findings demonstrate a substantial frequency of urinary Histoplasma antigen positivity in this selected cohort of symptomatic PLWH with suspected DH and support further evaluation of antigen-based diagnostic strategies in similar tertiary-care settings.