Disseminated Histoplasmosis Diagnostic Strategies in People Living With Hiv/AIds in an Endemic Region in Northeastern Brazil

Disseminated histoplasmosis (DH) is the most frequent opportunistic mycosis among people living with HIV/AIDS (PLWHA) in Ceará. This study aimed to evaluate diagnostic strategies for DH in PLWHA from 2020 to 2024 in an endemic region for histoplasmosis in northeastern Brazil. Cross-sectional study of hospitalized patients diagnosed with DH. PLWHA aged >18 years were included if they had proven DH (isolation of Histoplasma capsulatum in culture from buffy coat, bone marrow aspirate, or blood) or probable DH (positive urinary Histoplasma capsulatum antigen test—AgHc). Statistical analysis was performed using STATA 18.0. During the study period, 251 patients were hospitalized with a diagnosis of DH. The highest number of cases occurred in 2022 (n = 57) and 2023 (n = 56). Most patients were male (83.7%), with a mean age of 38 years. Mean CD4+ count was 52 cells/mm³, and the mean HIV viral load log was 5.16. The AgHc test was performed in 54 patients and was positive in 94.4% of cases. The methodologies used for AgHc testing were enzyme-linked immunosorbent assay (ELISA) in 44.4% (n = 24/54) and lateral flow assay (LF) in 55.6% (n = 30/54). Among negative AgHc tests (n = 3), two were by LF and one by ELISA; however, these cases were confirmed by isolation of H. capsulatum in buffy coat culture. Culture and direct microscopy for the fungus in buffy coat were performed in 248 patients. Fungal isolation from buffy coat was obtained in 92.3% of cases, and direct examination was positive in 53.6%. Among patients with negative buffy coat results (n = 19), all were confirmed by bone marrow aspirate culture. Isolation from bone marrow aspirate occurred in 46% of those tested (n = 89). Fungal blood culture was performed in 15 patients and was negative in 100% of cases. Most patients had proven DH (98.8%), and only three had probable DH, as they underwent only AgHc testing, which was positive. In Ceará, conventional diagnostic tests for DH remain widely used due to the scarcity of antigen testing. However, access to these tests should be universal for PLWHA with advanced HIV disease and clinical suspicion of DH, to enable early diagnosis and timely treatment.