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

Systematic Review of Prevalence of Histoplasma Antigenuria in Persons with HIV in Latin America and Africa

Histoplasmosis is a fungal disease associated with substantial mortality rates among persons with advanced HIV disease. Our systematic review synthesized data on the global prevalence of Histoplasma--caused antigenuria in persons with HIV. We searched PubMed/Medline, Embase, and Scopus databases on January 3, 2023, to identify cross-sectional and cohort studies evaluating Histoplasma antigenuria prevalence among adults with HIV infection. We calculated point estimates and 95% CIs to summarize prevalence. Of 1,294 studies screened, we included 15. We found Histoplasma antigenuria among 581/5,096 (11%; 95% CI 11%-12%) persons with HIV and 483/3,789 persons with advanced HIV disease (13%; 95% CI 12%-14%). Among persons with HIV and symptoms consistent with histoplasmosis, Histoplasma antigenuria prevalence was 14% (95% CI 13%-15%; 502/3,631 participants). We determined that persons with advanced HIV disease, inpatients, and symptomatic persons might benefit from a systematic approach to early detection of histoplasmosis using urine antigen testing.

Histoplasma antigens as novel players for the development of new enzyme immunoassays for the serodiagnosis of histoplasmosis: A comparative study of their analytical performance

Definitive diagnosis of histoplasmosis relies on culture and/or cytology/histopathology; however, these procedures have limited sensitivity and cultures are time-consuming. Antibodies detection by immunodiffusion has low sensitivity in immunocompromised individuals and uses histoplasmin (HMN), a crude antigenic extract, as reagent. Novel protein antigen candidates have been recently identified and produced by DNA-recombinant techniques to obtain standardized and specific reagents for diagnosing histoplasmosis. To compare the analytical performance of novel enzyme-linked immunosorbent assays (ELISAs) for antibodies testing for diagnosing histoplasmosis using different Histoplasma capsulatum antigens as reagents. The H. capsulatum 100 kDa protein (Hcp100), the M antigen and its immunoreactive fragment F1 were produced by DNA-recombinant techniques. Galactomannan was purified from both the yeast and mycelial cell walls (yGM and mGM, respectively). The analytical performance of the ELISA tests for the serological detection of antibodies against these antigens was evaluated and compared with those obtained using HMN as reagent. Antibodies detection by the Hcp100 ELISA demonstrated 90.0% sensitivity and 92.0% specificity, versus 43.3% sensitivity and 95.0% specificity of the M ELISA, 33.3% sensitivity and 84.0% specificity of the F1 ELISA, 96.7% sensitivity and 94.0% specificity of the yGM ELISA, 83.3% sensitivity and 88.0% specificity of the mGM ELISA, and 70.0% sensitivity and 86.0% specificity for the HMN ELISA. In summary, Hcp100 is proposed as the most promising candidate for the serodiagnosis of histoplasmosis. The primary immunoreactive element in HMN proved to be GM rather than the M antigen. Nevertheless, a higher incidence of cross-reactions was noted with GM compared to M.

Disseminated histoplasmosis in an HIV/AIDS transgender male-to-female with atypical and persistent GI manifestations

Disseminated histoplasmosis is a rare complication of infection due to Histoplasma capsulatum. Typically, histoplasmosis is self-limiting and asymptomatic in infected individuals with immunocompetence. Disseminated disease, however, can arise in high-risk populations with primary or acquired cellular immunodeficiency including HIV/AIDS, transplant recipients, and those undergoing immunosuppressive therapy. Here we describe a unique case of extrapulmonary gastrointestinal histoplasmosis by infiltrative Peyer's patch disease with bone marrow involvement in a transgender HIV-infected woman.

Identification and production of novel potential pathogen-specific biomarkers for diagnosis of histoplasmosis

IMPORTANCE

Histoplasmosis is considered one of the most important mycoses due to the increasing number of individuals susceptible to develop severe clinical forms, particularly those with HIV/AIDS or receiving immunosuppressive biological therapies, the high mortality rates reported when antifungal treatment is not initiated in a timely manner, and the limitations of conventional diagnostic methods. In this context, there is a clear need to improve the capacity of diagnostic tools to specifically detect the fungal pathogen, regardless of the patient's clinical condition or the presence of other co-infections. The proposed novel pathogen-specific biomarkers have the potential to be used in immunodiagnostic platforms and antifungal treatment monitoring in histoplasmosis. In addition, the bioinformatics strategy used in this study could be applied to identify potential diagnostic biomarkers in other models of fungal infection of public health importance.

Evaluation of the Histoplasma capsulatum 100-kilodalton antigen dot blot for the rapid diagnosis of progressive histoplasmosis in HIV/AIDS patients

Among people living with HIV (PLHIV), progressive disseminated histoplasmosis (PDH) represents an important cause of mortality. Since antigen detection allows a rapid diagnosis and the instauration of a specific treatment this study aimed to evaluate the analytical performance of the Hcp100 dot blot, an in-house assay that detects the Histoplasma capsulatum 100-kilodalton antigen in urine and compare it with 2 commercially available assays the Histoplasma Urine Antigen Lateral Flow Assay (MVD-LFA) (MiraVista® Diagnostics) and the Clarus Histoplasma Galactomannan EIA (Clarus HGM) (IMMY). Urine specimens from 23 PLHIV with PDH, 13 patients with other infectious diseases, and 20 healthy individuals were tested. The Hcp100 dot blot showed higher sensitivity (87.0%), specificity (97.0%) and accuracy (92.9%) than the MVD-LFA (73.9%, 78.8%, and 76.8%, respectively) and the Clarus HGM (78.3%, 90.9%, and 85.7%, respectively). The Hcp100 dot blot had high analytical performance and would be a valuable screening tool for diagnosing PDH among PLHIV.

Cost-effectiveness evaluation of routine histoplasmosis screening among people living with advanced HIV disease in Latin America and the Caribbean

Histoplasma antigen can be detected in people with advanced HIV disease (AHD), allowing for early and accurate diagnosis of histoplasmosis. The aim of this analysis was to assess the cost-effectiveness of routine histoplasmosis screening using antigen detection, among people with AHD. We developed a decision analytic model to evaluate Histoplasma antigen screening among people with AHD. The model estimated the costs, effectiveness, and cost-effectiveness of routine screening for Histoplasma antigen compared to the current practice of no routine Histoplasma antigen screening. The model includes stratification by symptoms of histoplasmosis, severity of presentation, and estimates of 30-day mortality. Data sources were taken from the Pan American Health Organization (PAHO) Strategic Fund databases on public purchases of medicines, and published literature on treatment outcomes. Outcome measures are life years saved (LYS), costs (US dollars), and incremental cost-effectiveness ratios (ICERs). Routine Histoplasma antigen screening avoids an estimated 17% of deaths in persons with advanced HIV disease, and is cost-effective compared to no histoplasmosis screening, with an ICER of $26/LYS. In sensitivity analysis assuming treatment for histoplasmosis with liposomal amphotericin, Histoplasma antigen screening remains cost-effective with an ICER of $607/LYS. Histoplasma antigen screening among people with AHD is a cost-effective strategy and could potentially avert 17% of AIDS-related deaths. Prospective evaluation of histoplasmosis screening is warranted to determine effectiveness and treatment outcomes with this strategy.

Advanced HIV disease: A review of diagnostic and prophylactic strategies

BACKGROUND

Despite expanded access to antiretroviral therapy (ART) and the rollout of the World Health Organization's (WHO) 'test-and-treat' strategy, the proportion of people with HIV (PWH) presenting with advanced HIV disease (AHD) remains unchanged at approximately 30%. Fifty percent of persons with AHD report prior engagement to care. ART failure and insufficient retention in HIV care are major causes of AHD. People living with AHD are at high risk for opportunistic infections and death. In 2017, the WHO published guidelines for the management of AHD that included a comprehensive package of care for screening and prophylaxis of major opportunistic infections (OIs). In the interim, ART regimens have evolved: integrase inhibitors are first-line therapy globally, and the diagnostic landscape is evolving. The objective of this review is to highlight novel point-of-care (POC) diagnostics and treatment strategies that can facilitate OI screening and prophylaxis for persons with AHD.

METHODS

We reviewed the WHO guidelines for recommendations for persons with AHD. We summarized the scientific literature on current and emerging diagnostics, along with emerging treatment strategies for persons with AHD. We also highlight the key research and implementation gaps together with potential solutions.

RESULTS

While POC CD4 testing is being rolled out in order to identify persons with AHD, this alone is insufficient; implementation of the Visitect CD4 platform has been challenging given operational and test interpretation issues. Numerous non-sputum POC TB diagnostics are being evaluated, many with limited sensitivity. Though imperfect, these tests are designed to provide rapid results (within hours) and are relatively affordable for resource-poor settings. While novel POC diagnostics are being developed for cryptococcal infection, histoplasmosis and talaromycosis, implementation science studies are urgently needed to understand the clinical benefit of these tests in the routine care.

CONCLUSIONS

Despite progress with HIV treatment and prevention, a persistent 20%-30% of PWH present to care with AHD. Unfortunately, these persons with AHD continue to carry the burden of HIV-related morbidity and mortality. Investment in the development of additional POC or near-bedside CD4 platforms is urgently needed. Implementation of POC diagnostics theoretically could improve HIV retention in care and thereby reduce mortality by overcoming delays in laboratory testing and providing patients and healthcare workers with timely same-day results. However, in real-world scenarios, people with AHD have multiple comorbidities and imperfect follow-up. Pragmatic clinical trials are needed to understand whether these POC diagnostics can facilitate timely diagnosis and treatment, thereby improving clinical outcomes such as HIV retention in care.

The Current and Future States of Diagnostic Tests for Histoplasmosis with a Focus on People with HIV and Disseminated Histoplasmosis

Histoplasmosis is caused by Histoplasma capsulatum and, although endemic in large parts of the world, is often underrecognized in many locations. In addition to underrecognition, inadequate availability of diagnostic tests is a major contributor to poor outcomes in disseminated disease in people with HIV. For those with advanced HIV and disseminated disease, antibody testing is less useful. Culture and histopathology can be useful in this situation, but each has limitations, including variable sensitivity by site and, in the case of culture, the need for a biosafety level three laboratory and a long period of growth. Antigen testing has proven useful for disseminated histoplasmosis due to the excellent sensitivity of urine. Yet, turnaround is slower than ideal due to use in a limited number of centers. The development of lateral flow assays has the potential to make for true rapid point-of-care assays for histoplasmosis, but in order to meet that promise, the tests must be widely available and affordable.

Tackling Histoplasmosis Infection in People Living with HIV from Latin America: From Diagnostic Strategy to Public Health Solutions

Histoplasmosis, caused by the thermally dimorphic fungus Histoplasma spp., is a disease with a broad clinical spectrum, presenting from asymptomatic/flu-like symptoms to progressive disseminated disease in people with immunosuppression. In recent years, the concept of histoplasmosis as a disease restricted to the American continent has changed, as now histoplasmosis is reported in many regions around the world. In Latin America, histoplasmosis represents a threat, especially in people with advanced HIV disease (AHD). Diagnosis of histoplasmosis in people living with HIV (PLHIV) is challenging due to the low index of suspicion of the disease, non-specificity of signs and symptoms, and limited access to specific laboratory testing, while the diagnostic delay is significantly associated with mortality. In the last decade, novel diagnostic tests have been developed for the rapid detection of histoplasmosis, such as commercial kits for antigen detection. Furthermore, advocacy groups were created that presented histoplasmosis as a public health problem, with emphasis on patients at risk of progressive disseminated disease. This review aims to discuss the impact of histoplasmosis associated with AHD in Latin America and the strategies employed to tackle histoplasmosis, from the implementation of laboratory testing to disease advocacy and public health interventions.

The incidence of histoplasmosis and cryptococcal antigenemia among patients attending a large HIV clinic in Trinidad

Our aim was to determine the incidence disseminated histoplasmosis and cryptococcal antigenemia among 280 patients with a CD4<350 cells/mm³ attending a large HIV clinic in Trinidad over the period November 2021-June 2022. Sera were screened for cryptococcal antigen (CrAg) using the Immy CrAg Immunoassay (EIA) and the Immy CrAg lateral flow assay (LFA). Urine was screened for Histoplasma antigen using the Immy EIA and the Optimum Imaging Diagnostics (OIDx) LFA. For the purposes of analysis, it was assumed, that all patients with positive urine Histoplasma antigen tests by both EIA and LFA and those with a single positive urine Histoplasma antigen test and clinical features of disseminated histoplasmosis were true positives. The incidence of probable disseminated histoplasmosis and cryptococcal antigenemia were 6.4% (18/280) and 2.5% (7/280) respectively. The sensitivity and specificity of the Immy Histoplasma EIA were 100% (95% CI, 81.5%-100%) and 98.5% (95% CI, 96.1% - 99.6%) respectively as compared to the OIDx Histoplasma LFA of 88.9% (95% CI, 65.3% - 98.6%) and 93.9% (95% CI, 90.3% - 96.5%) respectively, with substantial agreement between the 2 test kits (Kappa value = 0.763; 95% CI 0.685, 0.841). Testing for disseminated histoplasmosis in HIV patients is important in endemic areas.

Pulmonary Histoplasmosis: A Clinical Update

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. The areas of highest endemicity lie within the Mississippi and Ohio River Valleys of North America and parts of Central and South America. The most common clinical presentations include pulmonary histoplasmosis, which can resemble community-acquired pneumonia, tuberculosis, sarcoidosis, or malignancy; however, certain patients can develop mediastinal involvement or progression to disseminated disease. Understanding the epidemiology, pathology, clinical presentation, and diagnostic testing performance is pivotal for a successful diagnosis. While most immunocompetent patients with mild acute or subacute pulmonary histoplasmosis should receive therapy, all immunocompromised patients and those with chronic pulmonary disease or progressive disseminated disease should also receive therapy. Liposomal amphotericin B is the agent of choice for severe or disseminated disease, and itraconazole is recommended in milder cases or as "step-down" therapy after initial improvement with amphotericin B. In this review, we discuss the current epidemiology, pathology, diagnosis, clinical presentations, and management of pulmonary histoplasmosis.

Molecular Diagnosis of Endemic Mycoses

Diagnosis of endemic mycoses is still challenging. The moderated availability of reliable diagnostic methods, the lack of clinical suspicion out of endemic areas and the limitations of conventional techniques result in a late diagnosis that, in turn, delays the implementation of the correct antifungal therapy. In recent years, molecular methods have emerged as promising tools for the rapid diagnosis of endemic mycoses. However, the absence of a consensus among laboratories and the reduced availability of commercial tests compromises the diagnostic effectiveness of these methods. In this review, we summarize the advantages and limitations of molecular methods for the diagnosis of endemic mycoses.

Validation of a Lateral Flow Assay for Rapid Diagnosis of Histoplasmosis in Advanced HIV Disease, Buenos Aires, Argentina

Histoplasmosis is a major cause of mortality in individuals with advanced human immunodeficiency virus (HIV) disease (AHD). We evaluated in patients with AHD a lateral flow assay (LFA) developed by MiraVista® Diagnostics (MVD LFA). Histoplasmosis was defined based on the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) case definitions. We also compared the results of this LFA with those obtained using a commercial enzyme immunoassay (EIA) developed by IMMY, Clarus Histoplasma GM EIA, IMMY (HGM EIA). A retrospective observational study was conducted at Hospital Juan A. Fernández, located in Buenos Aires, Argentina. The study included 48 urine specimens from patients aged >18 years with AHD. Urine specimens included 17 patients with disseminated histoplasmosis and 31 specimens from patients without evidence of histoplasmosis. Specimens were tested using the MVD LFA and the HGM EIA. The MVD LFA and the HGM EIA had similar analytical performance, with a sensitivity of 94%, specificity of 100%, positive predictive value of 100%, negative predictive value of 97%, and an accuracy of 98%. Comparison of the MVD LFA with the HGM EIA demonstrated a Kappa agreement index of 0.906. The LFA evaluated in this study had high analytical performance; it provided rapid diagnosis of histoplasmosis with minimal requirements for laboratory training, equipment, and laboratory infrastructure.

Development of an Interferon-Gamma Release Assay (IGRA) to Aid Diagnosis of Histoplasmosis

Establishing diagnosis of latent and active histoplasmosis is challenging. Interferon gamma-release assays (IGRAs) may provide evidence of latent and active infection. An enzyme-linked immunospot (ELISpot) assay was developed using yeast cell lysate (YCL) antigen prepared from a representative North American Histoplasma capsulatum strain. Assay parameters were optimized by measuring responses in healthy volunteers with and without Histoplasma infection. Assay performance as an aid for diagnosing histoplasmosis was assessed in a prospective cohort of 88 people with suspected or confirmed infection, and 44 healthy controls enrolled in two centers in North America (2013 to 2018). Antigen specificity of IFN-γ release was demonstrated using ELISpot and enzyme-linked immunosorbent assay (ELISA). Antigen-evoked, single-cell mRNA expression by memory T cells was shown using flow cytometry. The area under the receiver operating characteristic curve (AUC) was estimated at 0.89 (95% confidence interval [CI]: 78.5% to 99.9%). At optimal cutoff, sensitivity was 77.2% (95% CI: 54.6% to 92.2%) and specificity was 100% (95% CI: 89.7% to 100%). Sixteen of 44 healthy volunteers (36.4%) from a region of hyperendemicity had positive responses, suggesting detection of previously unrecognized (latent) infection. The ELISpot assay is sensitive and specific as an aid to diagnose H. capsulatum infection and disease, supporting proof of concept and further development.

Progressive disseminated histoplasmosis in HIV-positive patients

BACKGROUND

Histoplasmosis is the most common endemic mycosis among people living with advanced HIV infection.

PURPOSE

Describe general aspects and challenges of this disease and its association with HIV.

RESEARCH DESIGN

Review of literature.

STUDY SAMPLE

Articles found using different combinations of terms including "disseminated histoplasmosis" and AIDS/HIV or immunosuppression in PubMed, Scopus, WHO Global health library, and Scielo database.

ANALYSIS

We look for information on epidemiology, pathogenesis, diagnosis, and treatment of histoplasmosis in AIDS patients.

RESULTS

Histoplasmosis is caused by Histoplasma capsulatum, a dimorphic fungus encountered throughout the world, mainly in soil enriched with bat and bird excreta. Progressive disseminated histoplasmosis is the main presentation of this mycosis in people living with advanced HIV and is fatal if left untreated. Symptoms include a systemic disease characterized by fever, weight loss, night sweats, skin manifestations, hepatomegaly, splenomegaly, and septic shock. Diagnostic tests include culture, visualization of H. capsulatum by direct and histopathological examination, serology, antigen, molecular, and skin testing. Patients with disseminated disease require aggressive and prolonged treatment to eradicate the pathogen and include amphotericin B and itraconazole. In many low income countries of endemic regions, histoplasmosis in HIV-positive patients is often undiagnosed or misdiagnosed as another opportunistic infection, due to the similarity in clinical manifestations and to the paucity of better diagnostic tests.

CONCLUSION

Histoplasmosis remains a neglected disease. Few studies about the disease and expensive treatments make it difficult to reduce the morbidity and mortality of this condition. Public health services and physicians must be aware of histoplasmosis' burden among the HIV-positive population.

A Simple Predictive Score to Distinguish between Disseminated Histoplasmosis and Tuberculosis in Patients with HIV

Disseminated histoplasmosis is a common differential diagnosis of tuberculosis in disease-endemic areas. We aimed to find a predictive score to orient clinicians towards disseminated histoplasmosis or tuberculosis when facing a non-specific infectious syndrome in patients with advanced HIV disease. We reanalyzed data from a retrospective study in Cayenne Hospital between January 1997-December 2008 comparing disseminated histoplasmosis and tuberculosis: 100 confirmed disseminated histoplasmosis cases and 88 confirmed tuberculosis cases were included. A simple logit regression model was constructed to predict whether a case was tuberculosis or disseminated histoplasmosis. From this model, a score may be obtained, where the natural logarithm of the probability of disseminated histoplasmosis/tuberculosis = +3.917962 × WHO performance score (1 if >2, 0 if ≤2) -1.624642 × Pulmonary presentation (1 yes, 0 no) +2.245819 × Adenopathies > 2 cm (1 yes, 0 no) -0.015898 × CD4 count - 0.001851 × ASAT - 0.000871 × Neutrophil count - 0.000018 × Platelet count + 6.053793. The area under the curve was 98.55%. The sensitivity of the model to distinguish between disseminated histoplasmosis and tuberculosis was 95% (95% CI = 88.7-98.3%), and the specificity was 93% (95% CI = 85.7.3-97.4%). In conclusion, we here present a clinical-biological predictive score, using simple variables available on admission, that seemed to perform very well to discriminate disseminated histoplasmosis from tuberculosis in French Guiana in well characterized patients.

Minimally Invasive Tissue Sampling: A Tool to Guide Efforts to Reduce AIDS-Related Mortality in Resource-Limited Settings

BACKGROUND

Available information on the causes of death among people living with human immunodeficiency virus (PLHIV) in low- and middle-income countries (LMICs) remains scarce. We aimed to provide data on causes of death in PLHIV from two LMICs, Brazil and Mozambique, to assess the impact of clinical misdiagnosis on mortality rates and to evaluate the accuracy of minimally invasive tissue sampling (MITS) in determining the cause of death in PLHIV.

METHODS

We performed coupled MITS and complete autopsy on 164 deceased PLHIV (18 children, 36 maternal deaths, and 110 adults). HIV antibody levels and HIV RNA viral loads were determined from postmortem serum samples.

RESULTS

Tuberculosis (22.7%), toxoplasmosis (13.9%), bacterial infections (13.9%), and cryptococcosis (10.9%) were the leading causes of death in adults. In maternal deaths, tuberculosis (13.9%), bacterial infections (13.9%), cryptococcosis (11.1%), and cerebral malaria (8.3%) were the most frequent infections, whereas viral infections, particularly cytomegalovirus (38.9%), bacterial infections (27.8%), pneumocystosis (11.1%), and HIV-associated malignant neoplasms (11.1%) were the leading cause among children. Agreement between the MITS and the complete autopsy was 100% in children, 91% in adults, and 78% in maternal deaths. The MITS correctly identified the microorganism causing death in 89% of cases.

CONCLUSIONS

Postmortem studies provide highly granular data on the causes of death in PLHIV. The inaccuracy of clinical diagnosis may play a significant role in the high mortality rates observed among PLHIV in LMICs. MITS might be helpful in monitoring the causes of death in PLHIV and in highlighting the gaps in the management of the infections.

Validation and Concordance Analysis of a New Lateral Flow Assay for Detection of Histoplasma Antigen in Urine

Histoplasmosis is a major cause of mortality in people living with HIV (PLHIV). Rapid methods to diagnose Histoplasma capsulatum disease could dramatically decrease the time to initiate treatment, resulting in reduced mortality. The aim of this study was to validate a MiraVista^® Diagnostics (MVD) Histoplasma urine antigen lateral flow assay (MVD LFA) for the detection of H. capsulatum antigen (Ag) in urine and compare this LFA against the MVista^®&nbsp;Histoplasma Ag quantitative enzyme immunoassays (MVD EIA). We assessed the MVD LFA using a standardized reference panel of urine specimens from Colombia. We tested 100 urine specimens, 26 from PLHIV diagnosed with histoplasmosis, 42 from PLHIV with other infectious diseases, and 32 from non-HIV infected persons without histoplasmosis. Sensitivity and specificity of the MVD LFA was 96%, compared with 96% sensitivity and 77% specificity of the MVD EIA. Concordance analysis between MVD LFA and the MVD EIA displayed an 84% agreement, and a Kappa of 0.656. The MVD LFA evaluated in this study has several advantages, including a turnaround time for results of approximately 40 min, no need for complex laboratory infrastructure or highly trained laboratory personnel, use of urine specimens, and ease of performing.

Diagnosis of Pulmonary Infections Due to Endemic Fungi

Endemic mycoses including Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and Talaromyces are dimorphic fungi that can cause a variety of clinical manifestations, including respiratory infections. Their pulmonary presentations are variable, and diagnosis is often delayed as they can mimic other infectious and non-infectious causes of pulmonary disease. Delay in diagnosis can lead to unnecessary antibiotic use, repeat hospitalizations, and increased morbidity and mortality. The diagnosis of endemic fungal pulmonary infections often relies on multiple diagnostic tests including culture, tissue histopathology, antigen assays, and antibody assays. Due to the increased use of immunosuppressive agents and the widening geographic ranges where these infections are being found, the prevalence of endemic fungal infections is increasing. Physicians need to be aware of the clinical manifestations of pulmonary infections due to endemic fungal in order to ensure that the proper diagnostic work up is obtained promptly. A high index of suspicion is particularly important in patients with suspected pulmonary infections who have failed to improve despite antibiotics in the appropriate setting. We present a review diagnostic testing for pulmonary infections due to endemic mycoses.

Implementation of rapid diagnostics assays for detection of histoplasmosis and cryptococcosis in central american people living with HIV

Objectives

Histoplasmosis and cryptococcosis are important public health problems in people living with HIV (PLHIV) in Central America. Conventional laboratory assays, based on microscopy and culture, are not optimal for the diagnosis of either disease. However, antigen (Ag) assays are rapid and highly accurate for the diagnosis of these infections.

Methods

Laboratory surveillance of PLHIV was carried out in four hospitals in Panama, Honduras and Nicaragua, between 2015 and 2019. Detection of Histoplasma antigens in urine was performed by enzyme immunoassay (EIA), and Cryptococcus antigen detection in sera and cerebrospinal fluid specimens was performed by lateral flow assay (LFA).

Results

A total of 4,453 PLHIV with clinical suspicion of histoplasmosis (n = 1,343) or cryptococcosis (n = 3,110; 2,721 sera and 389 CSF) were tested. Of 1,343 patients suspected of having histoplasmosis, 269 (20%) were Histoplasma Ag positive. Of 3,110 patients tested using the Cryptococcus Ag assay, 329 (11%) were positive. Honduras reported the highest positivity rates (32% for Histoplasma Ag, and 16% for Cryptococcus Ag); Panama reported the largest number of patients testing positive using the Histoplasma Ag assay (n = 201); and Nicaragua reported the largest number of patients testing positive using the Cryptococcus Ag assay (n = 170).

Conclusion

Here, we show how the implementation of rapid diagnostics assays impacted case detection and was useful for the care of people with advanced HIV. Rapid and accurate diagnosis could reduce mortality associated with histoplasmosis and cryptococcosis in PLHIV.

Combining urine antigen and blood polymerase chain reaction for the diagnosis of disseminated histoplasmosis in hospitalized patients with advanced HIV disease

Disseminated histoplasmosis (DH) is endemic in Latin America and the Caribbean where diagnostic tools are restricted. We carried-out a 1-year prospective cohort study at a referral hospital in São Paulo, Brazil. Participants had > or =18 years old, were hospitalized due to any indication and had CD4+ < 200 cells/µl. A urine commercial monoclonal Histoplasma galactomannan enzyme-linked immunosorbent assay (IMMY, Norman, OK, USA) and 'in house' Histoplasma blood nested PCR were performed in all cases. Probable/proven DH cases were defined according to international guidelines. Conventional mycological methods were available in routine conditions to investigate suspected DH cases. Treatment of participants followed the institutional routine. One-hundred six participants were included. Median age (interquartile range [IQR]) was 39.5 years (30.0-47.3) and 80 individuals (75.5%) were males. Median (IQR) CD4 cell count was 26.5 (9.4-89.3) cells/mm3. DH was diagnosed in 8/106 patients (7.5%). Antigen assay and/or PCR were positive in 4.7% (5/106) of patients. The antigen assay and/or PCR identified 37.5% (3/8) of DH cases, which had not been diagnosed with conventional mycological methods, but had clinical manifestations compatible with HD. In conclusion, the use of Histoplasma urine antigen and Histoplasma blood PCR guided by CD4 status contributed to the diagnosis of DH in hospitalized individuals. These assays were complementary to conventional mycologic methods and are urgently needed in our setting.

LAY SUMMARY

In this prospective cohort study carried-out in a referral center in São Paulo, Brazil, we found a high frequency of AIDS-related disseminated histoplasmosis (8/106, 7.5%). We used urine antigen test and blood PCR assay to improve the diagnosis of this opportunistic disease.

Diagnosis of histoplasmosis: current status and perspectives

Histoplasmosis is a worldwide-distributed systemic mycosis caused by the dimorphic fungus Histoplasma capsulatum. Its clinical manifestations range from subclinical or mild respiratory illness to progressive disseminated histoplasmosis (PDH), a life-threatening disease, whose accurate diagnosis is still challenging and limited in many countries, where this disease is highly endemic. In this regard, Histoplasma antigen testing is now included in the WHO Essential Diagnostics List. The final diagnosis of histoplasmosis is established by culture and/or visualization of the yeast cells by cytology or histopathology using specific stains. However, both procedures have limited sensitivity to detect the disease and cultures are time-consuming. Antibody detection assays are effective for the subacute and chronic clinical forms of histoplasmosis. However, their sensitivity is low in the immunocompromised host. Several molecular "in-house" tests were also developed and showed promising results, but none of these tests are commercially available and their standardization and validation are still pending. Antigen detection assays have high sensitivity in PDH cases and are of great value for the follow-up of patients with histoplasmosis; however, cross-reactivity with other related fungi are common. In addition, this assay is expensive and only performed in few laboratories. Novel protein antigen candidates have been recently identified and produced by DNA-recombinant techniques in order to obtain standardized and specific reagents for the diagnosis of histoplasmosis, as opposed to the unspecific antigens or crude extracts currently used. This review describes the currently available assays, highlighting their strengths and limitations and reports the latest approaches to achieve reliable and rapid diagnostic tests for histoplasmosis. KEY POINTS: • PDH causes thousands of deaths per year globally. • Rapid accurate diagnosis of PDH is unfeasible in many regions. • Fast, accurate, and low-cost diagnostic alternatives are currently under development.

Summary of Guidelines for Managing Histoplasmosis among People Living with HIV

Histoplasmosis is a frequent fungal opportunistic infection in people living with HIV (PLHIV), associated every year to a total of 5% to 15% of AIDS-related deaths among this population. In 2020, the first global guidelines for diagnosing and managing disseminated histoplasmosis among PLHIV was published. This document recommends (1) detection of circulating Histoplasma antigens as the recommended laboratory assay to diagnose histoplasmosis among PLHIV; (2) the use of liposomal amphotericin for induction therapy in severe or moderately severe disease, followed by a maintenance therapy with itraconazole for 12 months; a shorter maintenance therapy could be considered if the patient is clinically stable and if immune status has improved; (3) antiretroviral therapy initiation as soon as possible among patients with histoplasmosis without involvement of central nervous system; and (4) that for the treatment of co-infection with histoplasmosis and tuberculosis (TB), treatment of TB should be initiated according to the World Health Organization treatment guidelines. Appropriate health education of providers, supportive supervision, and policy guidance for the care of PLHIV are required.

Characteristics and Opportunistic Infections of AIDS Patients in East Java Province in 2018

Background: Acquired immunodeficiency syndrome (AIDS) is a health problem in East Java. Opportunistic infections are one of the causes of morbidity and mortality in patients with human immunodeficiency virus (HIV) and AIDS in Indonesia. Purpose: This study aimed to describe the characteristics and opportunistic infections of AIDS patients in East Java Province, 2018. Methods: This study was conducted as observational descriptive research, and a survey was used as the research design. The research location was in East Java Provincial Health Office, and the study was carried out in August 2019. We used secondary data taken from the results of surveillance of AIDS patients in 2018. The sampling method of the study was total sampling, with 1,138 AIDS patients. The variables studied included the patients’ characteristics (sex, age, type of work, and risk factors) as well as the number and types of opportunistic infections. Results: The majority of the AIDS patients in East Java in this sample were male (70.74%), belonged to the adults (26–45 years old) group (62.65%), and worked as employees/laborers (46.08%). In terms of sexual orientation, the majority were heterosexuals (81.81%) or homosexuals (10.63%). The majority of patients experienced one type of opportunistic infection (46.08%), with histoplasmosis (48.77%) and tuberculosis (TB) (42.62%) as the most frequently experienced opportunistic infections. Conclusion: Characteristics that are risk factors for contracting AIDS in East Java include being male, being of adult age, working as an employee/laborer, and being heterosexual. There are also risks of opportunistic infections, particularly histoplasmosis and TB.

Cross-reactivity of a Histoplasma capsulatum antigen enzyme immunoassay in urine specimens from persons with emergomycosis in South Africa

Histoplasma antigen detection in urine is a rapid diagnostic method for disseminated histoplasmosis, although cross-reactivity has been reported in specimens from patients with other thermally dimorphic fungal infections. We tested urine specimens, from persons with suspected invasive fungal infections, using a commercial monoclonal antibody Histoplasma enzyme immunoassay (EIA) at a South African national mycology reference laboratory from August 2014 through December 2018. Corresponding fungal culture and histopathology results were obtained from an electronic laboratory information system. In some cases, cultured fungal isolates were sent with the urine specimen for species-level identification by phenotypic and molecular methods. Cross-reactivity was confirmed using culture filtrates of several fungal pathogens. Of 212 referred cases, 41 (19%) were excluded since they had no recorded clinical history (n = 1), alternative diagnoses were confirmed (n = 2), or no fungal culture or histopathology results (n = 38). Eighty-seven of 212 (41%) had laboratory evidence of an invasive fungal disease, while 84 (40%) did not. Of the 87 cases, 37 (43%) were culture-confirmed mycoses: emergomycosis (n = 18), histoplasmosis (n = 8), sporotrichosis (n = 6), cryptococcosis (n = 2), talaromycosis (n = 1), and other fungi isolated (n = 2). The sensitivity and specificity of the EIA were calculated for two groups: culture-confirmed (n = 37) and histology-confirmed invasive fungal disease (n = 50). The sensitivity and specificity of the EIA for diagnosis of histoplasmosis compared to culture were 88% (7/8, 95%CI 47-100%) and 72% (21/29, 95%CI 53-87%), respectively, and for diagnosis of emergomycosis/histoplasmosis compared to histology was 83% (29/35, 95%CI 66-93%) and 93% (14/15, 95%CI 68-100%), respectively. Cross-reactions occurred in urine specimens of patients with Emergomyces africanus infection and in culture filtrates of E. africanus, T. marneffei and Blastomyces species. A commercial Histoplasma EIA had satisfactory accuracy for diagnosis of culture-confirmed histoplasmosis, but cross-reacted in urine specimens from patients with invasive disease caused by the closely-related pathogen, E. africanus and in culture filtrates of E. africanus and other related fungi.

LAY SUMMARY

Emergomyces africanus and Histoplasma capsulatum are fungi that cause a multi-system disease among HIV-seropositive persons with a low CD4 cell count. Handling live cultures of these fungi to confirm a diagnosis requires specialized laboratory equipment and infrastructure which is infrequently accessible in low-resource settings. The features of the two diseases (i.e., disseminated histoplasmosis and emergomycosis) may be indistinguishable when infected tissue is prepared, stained, and examined under a microscope. Enzyme immunoassays (EIA) have been developed as rapid diagnostic tools for the detection of a cell wall component of H. capsulatum in urine specimens, although cross-reactions have been reported in specimens from patients with other fungal infections. We evaluated the accuracy of a commercial Histoplasma EIA to diagnose histoplasmosis and to assess cross-reactions in urine specimens from persons with emergomycosis and in cultures of E. africanus and related fungi. We report a sensitivity and specificity of 88% (95%CI 47-100%) and 72% (95%CI 53-87%) for diagnosis of histoplasmosis compared to culture and 83% (95%CI 66-93%) and 93% (95%CI 68-100%) for diagnosis of either histoplasmosis/emergomycosis compared to a diagnosis made by microscopic examination of infected tissue. The assay cross-reacted in urine specimens from patients with emergomycosis and in culture filtrates of related fungi. Although the EIA cross-reacted with other related fungi, this test can decrease the time to diagnosis and facilitate early treatment of emergomycosis and histoplasmosis in South Africa.

Diagnosis of Breakthrough Fungal Infections in the Clinical Mycology Laboratory: An ECMM Consensus Statement

Breakthrough invasive fungal infections (bIFI) cause significant morbidity and mortality. Their diagnosis can be challenging due to reduced sensitivity to conventional culture techniques, serologic tests, and PCR-based assays in patients undergoing antifungal therapy, and their diagnosis can be delayed contributing to poor patient outcomes. In this review, we provide consensus recommendations on behalf of the European Confederation for Medical Mycology (ECMM) for the diagnosis of bIFI caused by invasive yeasts, molds, and endemic mycoses, to guide diagnostic efforts in patients receiving antifungals and support the design of future clinical trials in the field of clinical mycology. The cornerstone of lab-based diagnosis of breakthrough infections for yeast and endemic mycoses remain conventional culture, to accurately identify the causative pathogen and allow for antifungal susceptibility testing. The impact of non-culture-based methods are not well-studied for the definite diagnosis of breakthrough invasive yeast infections. Non-culture-based methods have an important role for the diagnosis of breakthrough invasive mold infections, in particular invasive aspergillosis, and a combination of testing involving conventional culture, antigen-based assays, and PCR-based assays should be considered. Multiple diagnostic modalities, including histopathology, culture, antibody, and/or antigen tests and occasionally PCR-based assays may be required to diagnose breakthrough endemic mycoses. A need exists for diagnostic tests that are effective, simple, cheap, and rapid to enable the diagnosis of bIFI in patients taking antifungals.

Endemic mycoses: epidemiology and diagnostic strategies

INTRODUCTION

The global frequency of endemic mycoses has considerably increased, mainly due to environmental changes, population growth in endemic areas, and the increase in HIV-related immunosuppressed status. Among the most frequent endemic mycoses are coccidioidomycosis in semi-desert climates, and paracoccidioidomycosis, and histoplasmosis in tropical climates. The inoculum can enter the host through the airway or directly through the skin. Lymphatic and hematogenous spread may involve the skin.

AREAS COVERED

In this article, we provide up-to-date epidemiological and diagnostic data on major (histoplasmosis, paracoccidioidomycosis, coccidioidomycosis, blastomycosis) and minor (talaromycosis, adiaspiromycosis, emergomycosis) endemic mycoses.

EXPERT OPINION

Endemic mycoses include diseases with a localized endemic area, and a few of them converge. These mycoses all have in common the airway involvement and can cause pulmonary symptoms following initial asymptomatic infection. Among the risk groups to acquire these mycoses are travelers from endemic areas, archeologists, speleologists, and immigrants. Promising and useful diagnostic tools have been developed in endemic mycoses; however, most of them are not standardized or available in low-income countries.

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

Human histoplasmosis is a fungal infection caused by the inhalation of microconidia of the thermally dimorphic fungi Histoplasma capsulatum. Autochthonous cases of histoplasmosis have been diagnosed in almost every country, but it is considered an endemic infection in specific areas of the world. Many of them are popular travel destinations or the source of migratory movements. Thus, the vast majority of the registered cases in non-endemic countries are imported. They correspond to people having been exposed to the fungus in endemic locations as immigrants, expatriates, transient workers or tourists, with reported cases also associated to organ donation. Misdiagnosis and delays in initiation of treatment are not uncommon in cases of imported histoplasmosis. They are associated to high fatality-rates specially in patients with compromised cellular immunity in which progressive disseminated forms develop. The diagnosis of this infection in non-endemic countries is hampered by the lack of clinical suspicion and a dearth of available diagnostic tools adequate to offer rapid and accurate results. Non-culture-based assays such as nucleic-acid amplification tests present as a suitable alternative in this situation, offering improved sensitivity and specificity, shortened turnaround time, and increased biosafety by avoiding culture manipulation. In non-endemic regions, molecular techniques are being used mainly in laboratories from countries that have registered an increase in the incidence of imported cases. However, the number of published techniques is limited and lack consensus. Efforts are currently under way to standardize nucleic acid amplification-based techniques for its implementation in areas registering a rising number of imported cases.

Screening for invasive fungal disease using non-culture-based assays among inpatients with advanced HIV disease at a large academic hospital in South Africa

INTRODUCTION

Despite widespread access to antiretroviral therapy (ART), the burden of advanced HIV disease in South Africa is high. This translates into an increased risk of AIDS-related opportunistic infections, including invasive mycoses.

METHODS

Using a limited number of non-culture-based diagnostic assays, we aimed to determine the prevalence of invasive mycoses and tuberculosis among hospitalised adults with very advanced HIV (CD4 counts < 100 cells/µL) at a large academic hospital. We conducted interviews and prospective medical chart reviews. We performed point-of-care finger stick and serum cryptococcal antigen lateral flow assays; serum (1 → 3) ß-D-glucan assays; urine Histoplasma galactomannan antigen enzyme immunoassays and TB lipoarabinomannan assays.

RESULTS

We enrolled 189 participants from 5280 screened inpatients. Fifty-eight per cent were female, with median age 37 years (IQR: 30-43) and median CD4 count 32 cells/µL (IQR: 13-63). At enrolment, 60% (109/181) were receiving ART. Twenty-one participants (11%) had a diagnosis of an invasive mycosis, of whom 53% (11/21) had cryptococcal disease. Thirteen participants (7%) had tuberculosis and a concurrent invasive mycosis. ART-experienced participants were 60% less likely to have an invasive mycosis than those ART-naïve (adjusted OR: 0.4; 95% CI 0.15-1.0; P = .03). Overall in-hospital mortality was 13% (invasive mycosis: 10% [95% CI 1.2-30.7] versus other diagnoses: 13% (95% CI 8.4-19.3)).

CONCLUSIONS

One in ten participants had evidence of an invasive mycosis. Diagnosis of proven invasive fungal disease and differentiation from other opportunistic infections was challenging. More fungal-specific screening and diagnostic tests should be applied to inpatients with advanced HIV disease.

HIV-Associated Histoplasmosis: Current Perspectives

Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum. Infection develops by inhalation of microconidia from environmental sites inhabited by birds and bats. Disseminated disease is the usual presentation due to impaired cellular immunity. Common clinical manifestations include fever, fatigue, malaise, anorexia, weight loss, and respiratory symptoms. Histoplasma antigen detection is the most sensitive method for diagnosis. The sensitivity of the MVista^® Quantitative Histoplasma antigen enzyme immunoassay is 95-100% in urine, over 90% in serum and bronchoalveolar lavage (BAL) antigen and 78% in cerebral spinal fluid (CSF). A proven diagnosis can be established by culture or pathology with sensitivities between 70% and 80%. The sensitivity of antibody detection by immunodiffusion or complement fixation was between 60% and 70%. Diagnosis using molecular methods has not been adequately validated for implementation and FDA cleared assays are unavailable. Liposomal amphotericin B should be used for 1-2 weeks followed by itraconazole for at least one year until CD4 counts are above 150 cells/mm3, HIV viral load is below 400 copies/mL and Histoplasma urine antigen is negative. Serum itraconazole level should be monitored to avoid drug toxicity. Antigen should be measured periodically to establish that treatment is effective and to assist in identifying relapse. The incidence of immune reconstitution inflammatory syndrome is low but it must be considered in patients who are thought to be failing antifungal treatment as it does not respond to changing antifungal agents but rather to initiation of corticosteroid therapy. In this review, we discuss pathogenesis, clinical manifestations, diagnosis and treatment based on personal experience and relevant publications.

The Role of Molecular Tests in the Diagnosis of Disseminated Histoplasmosis

Histoplasmosis is an emerging fungal disease, with global distribution. The disseminated form of the disease is a more severe infection, generally associated with AIDS. Classic diagnostic methods for histoplasmosis consist of microscopy, culture, and histopathology. More recently, the importance of Histoplasma antigen detection has dominated the literature on histoplasmosis diagnosis, but the relevance of molecular assays has not been as much studied. Here we describe the results of a systematic literature review focusing on studies that mainly compared immunological techniques (Histoplasma urine antigen detection) with molecular tests for the diagnosis of histoplasmosis. In addition to the review of comparative studies using such diagnostic techniques, the literature on polymerase chain reaction (PCR) tests in patients with disseminated histoplasmosis is also summarized. Two studies reported the comparison between immunological and molecular methods applied simultaneously for the diagnosis of disseminated histoplasmosis. PCR demonstrates a satisfactory performance assisting in the detection of Histoplasma spp. DNA in clinical samples.

The Broad Clinical Spectrum of Disseminated Histoplasmosis in HIV-Infected Patients: A 30 Years' Experience in French Guiana

Histoplasmosis is a common but neglected AIDS-defining condition in endemic areas for Histoplasma capsulatum. At the advanced stage of HIV infection, the broad spectrum of clinical features may mimic other frequent opportunistic infections such as tuberculosis and makes it difficult for clinicians to diagnose histoplasmosis in a timely manner. Diagnosis of histoplasmosis is difficult and relies on a high index of clinical suspicion along with access to medical mycology facilities with the capacity to implement conventional diagnostic methods (direct examination and culture) in a biosafety level 3 laboratory as well as indirect diagnostic methods (molecular biology, antibody, and antigen detection tools in tissue and body fluids). Time to initiation of effective antifungals has an impact on the patient's prognosis. The initiation of empirical antifungal treatment should be considered in endemic areas for Histoplasma capsulatum and HIV. Here, we report on 30 years of experience in managing HIV-associated histoplasmosis based on a synthesis of clinical findings in French Guiana with considerations regarding the difficulties in determining its differential diagnosis with other opportunistic infections.