Histoplasmosis, An Underdiagnosed Disease Affecting People Living With HIV/AIDS in Brazil: Results of a Multicenter Prospective Cohort Study Using Both Classical Mycology Tests and Histoplasma Urine Antigen Detection

Background: Histoplasmosis is highly endemic in the American continent. This condition is associated with a high mortality, particularly in people living with HIV/AIDS (PLWHA). Diagnosis of histoplasmosis is usually late in South America, as Histoplasma antigen detection is rarely available. Here we determined the prevalence, risk factors, and outcome of histoplasmosis in PLWHA in Brazilian hospitals. Methods: This was a prospective cohort study (2016-2018) involving 14 tertiary medical centers in Brazil. We included hospitalized PLWHA presenting with fever and additional clinical findings. Patients were investigated at each participant center with classical mycology methods. Also, Histoplasma antigen detection was performed in urine samples (IMMY). Probable/proven histoplasmosis was defined according to European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group/National Institute of Allergy and Infectious Diseases Mycoses Study Group criteria. Results: From 616 eligible patients, 570 were included. Histoplasmosis was identified in 21.6% (123/570) of patients. Urine antigen testing increased the diagnostic yield in 53.8%, in comparison with standard mycology methods. Variables independently associated with histoplasmosis were CD4+ count <50 cells/mm3, use of an antiretroviral (protective effect), and sample collection in the Northeast region of Brazil. Dyspnea at presentation was independently associated with death. Histoplasmosis was more frequent than tuberculosis in patients with low CD4+ counts. Overall 30-day mortality was 22.1%, decreasing to 14.3% in patients with antigen-based diagnosis. Conclusions: Histoplasmosis is a very frequent condition affecting PLWHA in Brazil, particularly when CD4+ counts are lower than 50 cells/mm3. Antigen detection may detect earlier disease, with a probable impact on outcomes. Access to this diagnostic tool is needed to improve clinical management of PLWHA in endemic countries.