Can urinary histoplasma antigen test improve the diagnosis of histoplasmosis in a tuberculosis endemic region?

Abstract

Summary Background Many patients with histoplasmosis are treated with anti‐tubercular therapy (ATT) in tuberculosis endemic regions as diagnosis of histoplasmosis requires invasive sampling. We sought to study the utility of urinary Histoplasma antigen detection test. Methods Case records of patients with a diagnosis of histoplasmosis prior to (Period A) and after (Period B) introduction of urinary Histoplasma antigen detection test were analysed in this single centre retrospective study. Results Thirty‐seven patients (18 in Period A, and 19 patients in Period B) were studied. There was nearly a threefold increase in diagnoses (from 0.39 cases to 1.18 cases per month) after the introduction of antigen test. Nine patients (24.3%) were immunocompromised (6 had HIV infection and 3 were on steroids), and 28 (75.6%) were immunocompetent. Empirical ATT had been given to 10 patients prior to histoplasmosis diagnosis. Invasive tissue sampling was required in only two patients in Period B to confirm the diagnosis. Immunocompromised patients were younger, were more likely to have skin and mucosal findings, anaemia and leucopenia as compared to immune‐competent patients. Conclusion This study emphasises that histoplasmosis cases may be missed and patients may receive ATT unnecessarily. Histoplasma antigen increased the diagnostic yield by almost threefold in our study.

The Review of Histoplasmosis Endemicity and Current Status in Asia

“…The cases from Bangladesh were all adult males, with 15% (four patients) who had acquired immunodeficiency syndrome (AIDS). The predominance of male population with histoplasmosis was also found in many case series [42,50,59]. The most common type of histoplasmosis was disseminated histoplasmosis.…”

“…Diabetes 41 [30,35,47,48,53,59] Chronic granulomatous disease 2 [52,55] Corticosteroid therapy 3 [9,22,38] Other immunosuppressive therapies 2 [22,38] Idiopathic CD4 lymphocytopenia 2 [27,35] Kidney transplant 1 [29] TB with severe malnutrition 1 [35] Lymphoma 1 [35] Chronic liver disease 1 [59] Chronic kidney disease 1 [59] Total 55 13.75% was observed among 2,729 people from Bangladesh (formerly called East Pakistan) [92]. Meanwhile, all of the 575 people (healthy participants, schoolchildren and TB and leprosy patients) showed a zero rate of histoplasmin sensitivity in Pakistan [93].…”

Diagnosis of Progressive Disseminated Histoplasmosis in Advanced HIV: A Meta-Analysis of Assay Analytical Performance

“…In locations where these assays have been implemented, the performance of these more sensitive and specific assays have resulted in a significantly increased number of patients diagnosed compared with conventional diagnostic tests (culture and histopathology) [28,30,31]. Likewise, the relative ease and speed in which these antigen assays can be performed has resulted in a shortened time of diagnosis and a reduction of mortality associated with PDH in PLHIV [44,45,46,47]. Antigen assays can also be performed in laboratories that do not have the higher levels of biocontainment needed for handling Histoplasma cultures for conventional identification or DNA extractions for molecular identification.…”

Timely Diagnosis of Histoplasmosis in Non-endemic Countries: A Laboratory Challenge

“…Combined detection in serum and urine seem to provide the best diagnostic performance, with some differences in the diagnostic yield between FDA cleared tests (Theel et al, 2013;Fandiño-Devia et al, 2016;Azar and Hage, 2017;Torres-González et al, 2018). Antigen detection provides a clear improvement for the management of histoplasmosis, especially in highly endemic areas where this infection frequently coexists with tuberculosis (Bansal et al, 2019), and recently it has been included in the WHO list of essential diagnostic test 1 . Despite FDA-approved commercial tests are available, their use is mostly restricted to developed endemic areas (Bongomin et al, 2019a).…”