Search

Coccidioidomycosis, histoplasmosis, and blastomycosis are underrecognized and frequently misdiagnosed fungal infections that can clinically resemble bacterial and viral community-acquired pneumonia. This guidance is intended to help outpatient clinicians test for these fungal diseases in patients with community-acquired pneumonia to reduce misdiagnoses, unnecessary antibacterial use, and poor outcomes. [ABSTRACT FROM AUTHOR]

Immunocompromised host commonly develops a disseminated form of histoplasmosis and may have diverse manifestations. We present a case of histoplasmosis in a kidney transplant recipient who presented with pyrexia of unknown origin and pancytopenia. Bronchoalveolar lavage fluid analysis and serum antigen were negative for histoplasmosis. Bone marrow biopsy showed periodic acid–Schiff-positive intra and extracellular yeast-like organisms and later confirmed as Histoplasma capsulatum. The patient was successfully treated with intravenous liposomal amphotericin B, followed by oral itraconazole. Thus, bone marrow examination proved as key to diagnosis in our case. [ABSTRACT FROM AUTHOR]

Histoplasmosis is an endemic infection caused by Histoplasma capsulatum, leading to a broad spectrum of disease from asymptomatic to severe disseminated disease. To diagnose Histoplasmosis, culture remains the gold standard for the laboratory diagnosis; however, this fungus grows slowly, taking a long time 2 to 3 weeks or may take up to 8 weeks. Therefore, some other methods such as bone marrow examination play an essential role in rapid identification and early diagnosis, especially in cases of severe disseminated disease. In this case, we report a 55-year-old man with a 1-year history of gout, self-medicating (including Medrol) who was admitted to the hospital because of persistent fever and swelling of his left arm. About laboratory investigation, there was a bicytopenia (RBC and PLT), blood and pus cultures many times were negative. On the slide of the bone marrow specimen, images of yeast suspected of Histoplasma capsulatum were observed. Therefore, the patient was treated with antifungal medication, and the culture was repeated with prolonged follow-up time and positive results with H. capsulatum after 16 days. In conclusion, bone marrow test plays a significant role in the diagnosis of some fungal infections, which can contribute to an early diagnosis, especially in cases of culture and serological tests are not available or cannot be performed. Patients who present with fever and bicytopenia or pancytopenia should be performed early bone marrow test, which can support the earlier diagnosis to have appropriate treatment. [ABSTRACT FROM AUTHOR]

Angioimmunoblastic T-cell lymphoma (AITL) is an uncommon systemic lymphoproliferative disorder that comprises approximately one-fifth of all mature peripheral T-cell lymphomas. A broad range of cutaneous manifestations include maculopapular, papulovesicular, erythrodermic, urticarial, plaque-like and nodular, and they are mentioned in 50% of patients and may precede systemic symptoms, which include lymphadenopathy, hepatosplenomegaly and constitutional symptoms. Histoplasmosis is a common granulomatous infection worldwide caused by Histoplasma capsulatum, a dimorphic fungus. Cutaneous manifestations are reported to occur in 10% to 25% of immunosuppressed patients with disseminated histoplasmosis. Generalised pruritus as a presenting feature is rarely described in both of these entities. We report a unique case of AITL with histoplasmosis discovered during paraclinical assessment of generalised pruritus (? neurodermatitis) with prurigo-like lesions and lymphadenopathy. [ABSTRACT FROM AUTHOR]

Background - Histoplasmosis is a soil based rare air borne fungal infection and mostly documented in HIV positive patients. They are common in people living near valley region. Materials and methods- This is a multiinstitutional study. We report 3 cases of asian women from different regions of Southern Rajasthan who died due to delayed diagnosis of Histoplasmosiswithin few days of admission. They all had complaints of fatigue and fever since 1 month. One presented with decreased urine output and pancytopenia. Others had complaints of prolonged fever with pancytopenia and fatigue. All were diagnosed on Bone marrow examination for presence of Histoplasma Capsulatum, diagnosis was supported by special stains used for reporting. Treatment was started but patients deteriorated and died within 10 days of admission. Conclusion- Delay in diagnosis of Histoplasmosis leads to death of patients. So, Histoplasmosis is considered as a differential diagnosis of prolonged fever with pancytopenia and chronic infections. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 19-year-old male who had undergone heart and renal transplantation and was immunosuppressed, presenting with fevers, chills, cough, and other symptoms. He was found to have leukopenia, thrombocytopenia, acute kidney injury, deranged liver profile, and markedly elevated ferritin levels, with chest imaging showing abnormalities, prompting a diagnostic question about the underlying condition.

The authors offer a response to commentaries made on their article on clinical testing guidance for histoplasmosis in patients with community-acquired pneumonia. The respondents offer concern on the exclusion of enzyme immunoassay (EIA) Histoplasma antibody testing from the histoplasmosis algorithm. The authors agree with their comments about the potential benefits of using EIA antibody testing in acute pulmonary histoplasmosis and mention a limitation of the EIA Histoplasma antibody testing.

Histoplasmosis is an endemic infection caused by Histoplasma capsulatum, leading to a broad spectrum of disease from asymptomatic to severe disseminated disease. To diagnose Histoplasmosis, culture remains the gold standard for the laboratory diagnosis; however, this fungus grows slowly, taking a long time 2 to 3 weeks or may take up to 8 weeks. Therefore, some other methods such as bone marrow examination play an essential role in rapid identification and early diagnosis, especially in cases of severe disseminated disease. In this case, we report a 55-year-old man with a 1-year history of gout, self-medicating (including Medrol) who was admitted to the hospital because of persistent fever and swelling of his left arm. About laboratory investigation, there was a bicytopenia (RBC and PLT), blood and pus cultures many times were negative. On the slide of the bone marrow specimen, images of yeast suspected of Histoplasma capsulatum were observed. Therefore, the patient was treated with antifungal medication, and the culture was repeated with prolonged follow-up time and positive results with H. capsulatum after 16 days. In conclusion, bone marrow test plays a significant role in the diagnosis of some fungal infections, which can contribute to an early diagnosis, especially in cases of culture and serological tests are not available or cannot be performed. Patients who present with fever and bicytopenia or pancytopenia should be performed early bone marrow test, which can support the earlier diagnosis to have appropriate treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We sought to determine the prevalence of probable disseminated histoplasmosis among advanced HIV disease (AHD) patients in Nigeria. We conducted a cross-sectional study in 10 sites across 5 of 6 geopolitical zones in Nigeria. We identified patients with urinary samples containing CD4 cell counts <200 cells/mm3 or World Health Organization stage 3 or 4 disease who also had >2 clinical features of disseminated histoplasmosis, and we tested them for Histoplasma antigen using a Histoplasma enzyme immune assay. Of 988 participants we recruited, 76 (7.7%) were antigen-positive. The 76 Histoplasma antigen-positive participants had significantly lower (p = 0.03) CD4 counts; 9 (11.8%) were also co-infected with tuberculosis. Most antigen-positive participants (50/76; 65.8%; p = 0.015) had previously received antiretroviral treatment; 26/76 (34.2%) had not. Because histoplasmosis is often a hidden disease among AHD patients in Nigeria, Histoplasma antigen testing should be required in the AHD package of care. [ABSTRACT FROM AUTHOR]

We detected Histoplasma capsulatum in soil and penguin excreta in the Antarctic Peninsula by sequencing after performing species-specific PCR, confirming previous observations that this pathogen occurs more broadly than suspected. This finding highlights the need for surveillance of emerging agents of systemic mycoses and their transmission among regions, animals, and humans in Antarctica. [ABSTRACT FROM AUTHOR]

The rapid diagnosis of opportunistic infections (OIs) is critical for improving the health outcomes of people living with HIV/AIDS (PLWHA). This study aimed to describe the feasibility of implementing a package for the rapid diagnosis of tuberculosis, histoplasmosis, and cryptococcosis in patients with advanced HIV/AIDS disease in Porto Alegre, Brazil. The research involved two focus groups with health professionals, four in-depth interviews with healthcare managers, and twelve interviews with PLWHA. The corpus was analyzed using Descending Hierarchical Classification (DHC). The study found that the rapid test diagnosis intervention was generally well-received by patients and health professionals, improving diagnosis and treatment outcomes. However, it also identified several areas for improvement, including the need for expanded psychosocial support and enhanced coordination between health services. The findings have important implications for the development and implementation of policies and programs aimed at enhancing the diagnosis and treatment of OIs among PLWHA with advanced diseases. Further research should explore social determinants of HIV/AIDS mortality to offer valuable insights into improving prevention and treatment strategies. By prioritizing patient-centered care and improving coordination between health services, policymakers and health professionals can improve the health outcomes of PLWHA with advanced disease in Porto Alegre and other similar settings., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Brandelli Costa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Tuberculosis is a highly prevalent disease in India, while Histoplasmosis, an emerging disease, is often underreported due to limited resources in developing countries. Coinfection with both these organisms is rarely documented in immunocompetent host. Due to overlapping symptoms, it can be easily missed and treatment delays are not uncommon., Case Presentation: Here, we report a case of a 62-year-old male with a chronic history of intermittent fever and dry cough, splenomegaly, lymphadenopathy, and persistent pancytopenia. He was diagnosed with tuberculosis with cartridge-based nucleic acid amplification test (CBNAAT) positivity from a paratracheal lymph node biopsy. Simultaneously, a bone marrow biopsy revealed Histoplasmosis and the patient was started on dual treatment (Itraconazole and antitubercular drugs). After an initial response, the patient developed new space-occupying cerebral lesions. CSF histoplasma antigen was also positive. The reason for treatment failure was likely to be drug interaction (suboptimal levels of itraconazole due to rifampicin). The patient received liposomal amphotericin and subsequently put on a modified antitubercular treatment regimen to avoid interaction with itraconazole. At 2-month follow-up, the patient's condition significantly improved with a substantial resolution in CNS lesions., Conclusions: Histoplasmosis and tuberculosis have overlapping symptoms, diagnosing one does not preclude the possibility of other, even in non-HIV patients. Clinicians should also be vigilant about potential drug interactions., Competing Interests: Declarations Ethics approval and consent to participate This study did not require ethical approval. Consent for publication Written informed consent was obtained from the patient included in this report. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: Histoplasma is a fungal pathogen found in many parts of the world. In North America, its distribution is traditionally thought to be endemic to the Ohio and Mississippi River valleys. Development of histoplasmosis after Histoplasma exposure is related to degree of inoculum exposure and susceptibility, for example, immunocompromised status. Most exposed, healthy individuals are asymptomatic and few develop pulmonary symptoms. A limited number of infectious etiologies (that is, Histoplasma, Coccidioides, and Mycobacterium tuberculosis) can cause miliary pattern on chest imaging, and thus, histoplasmosis should be considered whenever a patient presents with pulmonary symptoms and these unique radiographic findings., Case Presentation: A previously healthy 13-year-old Hispanic male presented as a transfer from an outside hospital with fever and hypoxia in the setting of a progressive, subacute gastrointestinal illness. Given hypoxia, the concern for sepsis, and unclear etiology of his illness, broad-spectrum antimicrobial therapy and noninvasive ventilation were started. Initial evaluation demonstrated miliary pulmonary infiltrates, and travel history raised suspicion for coccidioidomycosis or tuberculosis. After a complete evaluation, lab studies confirmed a diagnosis of histoplasmosis, and the patient made a full recovery after the initiation and completion of antifungal therapy., Conclusion: Herein, we present a patient who acquired histoplasmosis from an area of Mexico not currently acknowledged as endemic and review recently published data emphasizing new areas of Histoplasma endemicity in North America, particularly the southwest USA and most states of Mexico. Though limited surveillance data exist, mounting case reports/series and local epidemiologic studies illustrate the expanding worldwide endemicity of Histoplasma and underscore histoplasmosis as a growing global health concern., (© 2024. The Author(s).)

Histoplasmosis is an increasing infection that mainly affects immunocompromised individuals such as patients with HIV/AIDS, with the disseminated form, especially gastrointestinal, being common in this population. The clinical presentation ranges from asymptomatic to symptoms that mimic other abdominal diseases. Jejunal perforation due to histoplasmosis, although rare, has been reported in a few cases, typically in men living with HIV in their fourth decade of life. We present the case of a 34-year-old male, with a history of HIV and colonic histoplasmosis who presented with acute abdominal pain requiring exploratory laparotomy and intestinal resection due to jejunal perforation, with histological confirmation of histoplasmosis in the resected intestinal segment.

A man in his early 30s presenting with chest pain was admitted for the management of acute pericarditis and evaluation of a subcarinal mass incidentally noted on chest imaging. Shortly after admission, he developed cardiac tamponade. Emergent pericardiocentesis revealed purulent pericardial fluid with polymicrobial anaerobic bacteria, raising concern for gastrointestinal source and broad intravenous antibiotics were given. The pericardial fluid reaccumulated despite an indwelling pericardial drain and intrapericardial fibrinolytic therapy, necessitating a surgical pericardial window. Concurrent fluoroscopic oesophagram demonstrated oesophageal perforation with fistulous connection to the subcarinal mass and mediastinal drain, suggestive of oesophagopericardial fistula. Pathology from biopsy of the subcarinal mass returned with focal large necrotising granulomas consistent with histoplasmosis. Antifungal treatment was initiated, and the patient was eventually discharged home with nasogastric feeding tube and oral antibiotics and antifungals. This is the first reported case of polymicrobial pericarditis secondary to acquired oesophagopericardial fistula likely induced by mediastinal histoplasma lymphadenitis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Histoplasmosis is a systemic infection caused by an endemic dimorphic fungus, Histoplasma capsulatum. Though prevalent in the eastern United States of America, near the Ohio and Mississippi River Valleys, the evidence underlying the global prevalence of histoplasmosis, especially in immunocompromised populations, is underappreciated. This article highlights the global epidemiology, risk factors, microbiology and pathophysiological characteristics, pulmonary and extrapulmonary manifestations, prevention measures, radiographic patterns, diagnostic techniques, and antifungal treatment approaches for Histoplasma capsulatum., Competing Interests: Declaration of competing interest All authors declare no conflicts of interest in relation to the main objectives of this work., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: To describe the incidence, prevalence, and clinical characteristics of presumed ocular histoplasmosis syndrome (POHS) in a Histoplasma endemic region.Methods: The International Classification of Diseases, 9th and 10th Revision codes were used to search the Rochester Epidemiology Project, a record-linkage system for medical care provided in Olmsted County, MN. Medical records were reviewed to confirm POHS diagnoses in county residents from January 1, 2006, to December 31, 2015. Age- and sex-adjusted incidence rates were calculated and adjusted to the 2010 U.S. White population.Results: There were 18 incident cases (30 eyes) and 87 prevalent cases (131 eyes). The incidence rate was 1.35 per 100,000 per year. The mid-study prevalence rate was 0.064%. Choroidal neovascularization (CNV) occurred in 17.4% of the affected eyes. At the last follow-up, 16.8% of the affected eyes had POHS-related decreased visual acuity (<20/40).Conclusion: This study assesses the epidemiology and clinical features of POHS in a Midwestern U.S. county.Abbreviations/acronyms: POHS = Presumed ocular histoplasmosis syndrome; ICD = International Classification of Diseases; CI = Confidence interval; VA = Visual acuity; Anti-VEGF = Anti-vascular endothelial growth factor; REP = Rochester Epidemiology Project, CNV = Choroidal neovascularization. [ABSTRACT FROM AUTHOR]

The article discusses a study by D. J. Smith and colleagues which offered clinical testing guidance to clinicians who evaluate patients with suspected community-acquired pneumonia (CAP) caused by endemic mycoses. Topics include diagnostic tests for the various manifestations of histoplasmosis, observations on patients with acute pulmonary histoplamosis, and testing that was found to be the most sensitive approach, detecting 98 percent of cases.

Hemophagocytic lymphohistiocytosis (HLH) is a disorder that occurs due to unsuitable monocyte activation in a variety of infections. In human immunodeficiency virus (HIV) infections, patients with advanced immunossupression associated with opportunistic infections are at increased risk of developing HLH. We describe a clinical case of a 33-year-old male student diagnosed with HIV who was hospitalized for investigation of asthenia and dyspnea, accompanied by adynamia, decreased motor force in the left leg, dysphagia, and dysfluency. His general condition was regular, he was pale, feverish, and had normal cardiac and pulmonary auscultation. Physical examination revealed ulcerated lesions in the perianal region and hepatosplenomegaly without palpable lymph node enlargement. Laboratory parameters showed pancytopenia, a slight increase in liver function accompanied by high lactate dehydrogenase, and hiperferritinemia. The initial diagnosis was disseminated histoplasmosis, thus amphotericin B deoxycholate was empirically prescribed while waiting on myeloculture and blood cultures for fungi and mycobacteria. Other clinical procedures were blood transfusion, resumption of antiretroviral therapy (ART) and secondary prophylaxis. Myeloculture blood cultures of fungi and mycobacteria were negative. Patient evolved well in relation to the initial complaints and showed partial clinical and laboratory improvement. However, 23 days after hospitalization, he developed a febrile episode accompanied by chills and a convulsive crisis. The patient was transferred to the intensive unit care and developed septic shock and respiratory failure. He died 25 days after the onset of the condition. After the postmortem examination, histopathology revealed countless rounded fungal structures compatible with Histoplasma sp., which were observed in the peripancreatic lymph node, liver, and spleen, in addition to hemophagocytosis in the splenic parenchyma. We thus conclude that when the patient met criteria for HLH, such as fever, hepatosplenomegaly, hiperferritinemia, and pancytopenia, the evolution was fast due to the aggressive and rapidly fatal nature of HLH, despite anti-fungal and corticoid treatment. Therefore, this case report reinforces the need to consider hemophagocytic syndrome in patients with HIV and disseminated histoplasmosis, especially where histoplasmosis is highly endemic, in order for the treatment be started early when there is high clinical suspicion. [ABSTRACT FROM AUTHOR]

Multidrug therapy has significantly reduced the global burden of Hansen's disease; however, complications from long-term treatment persist. A male resident of southern Kentucky, in his 30s and of Micronesian descent, presented with worsening abdominal pain associated with anorexia, fatigue, functional decline and occasional haemoptysis. He was compliant with multidrug therapy for leprosy. Laboratory investigations revealed pancytopenia. He was initially treated under a sepsis protocol and later switched to high-dose steroids due to a suspected immune reaction from missed corticosteroid doses. Despite aggressive treatment for refractory pancytopenia, the patient's condition deteriorated, and he passed away from cardiac arrest. Posthumous bone marrow biopsy revealed haemophagocytic lymphohistiocytosis secondary to disseminated histoplasmosis with bone marrow infiltration. This case highlights the importance of proactive fungal screening in immunocompromised leprosy patients, particularly in endemic regions, as early detection and timely intervention can prevent severe complications., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Histoplasma capsulatum is a thermally dimorphic fungal pathogen endemic to the Mississippi and Ohio River Valley regions of North America and much of Central and South America. As an opportunistic pathogen, H. capsulatum can assume a latent infection that can be reactivated by immunocompromised states or immunosuppressive therapy. We report a case of a 72-year-old man who lived in rural regions of Panama, Honduras, and Nicaragua while serving in the U.S. military from 1987 to 1991. Three decades after his initial exposure, the patient presented for evaluation of a painful tongue ulcer that originated when he began taking adalimumab to manage his psoriatic arthritis 2 years earlier. Tissue scraping of the tongue ulcer grew a whitish to cream-colored, fluffy-textured mold that was morphologically identified as Histoplasma. Molecular analysis of the fungus confirmed H. capsulatum var. Latin American group A, known as Histoplasma suramericanum. Further testing showed a positive H. capsulatum antibody mycelial complement fixation, and a 1-cm calcified nodule in the lower lobe of the left lung on computed tomography. Here, we highlight the importance of recognizing disseminated histoplasmosis in patients with exposure to endemic regions before initiating immunosuppressive therapy.

Histoplasmosis is caused by the fungus Histoplasma capsulatum and is often fatal for individuals with acquired immunodeficiency syndrome (AIDS). Delayed diagnosis is a major factor in worsening coinfection, as it can be mistaken for other diseases. Thus, rapid identification of Histoplasma in immunocompromised patients is essential. Molecular techniques, particularly polymerase chain reaction (PCR), were used in this study to identify H. capsulatum in patients coinfected with histoplasmosis and AIDS. Blood samples from 14 individuals with AIDS and disseminated histoplasmosis were collected and analyzed. The PCR method successfully amplified the fungal region in whole blood samples, while PCR-RFLP analysis confirmed a consistent profile in the samples. Genetic sequencing further confirmed the fungal species. Compared to clinical tests such as fungal culture and urinary antigen detection, molecular analysis proved faster, more sensitive, and cost-effective. These molecular markers can potentially be incorporated into routine diagnostics in the future. Further studies are needed to expand and enhance this diagnostic approach, particularly in patients with nonprogressive clinical forms of histoplasmosis.

A 54-year-old woman with progressive and non-acute dysphagia to solid foods, post-feeding vomiting, and weight loss of 10 kg in 1 year. As personal history, she was a former smoker of 60 pack-year, heart transplant for idiopathic dilated cardiomyopathy, and type 2 diabetes. She was on daily use of metformin and immunosuppressive drugs. The laboratory tests were all normal. Upper digestive endoscopy (UDE) revealed in the middle third of the esophagus a lesion of 3 cm presenting atypical rectified vessels, covering 50% of the esophageal lumen, suggestive type 0-IIc+IIa1 (A). The chromoendoscopy with Lugol iodine at 1.25% showed a positive pink sign (B). Biopsies showed esophagitis with mixed inflammatory infiltrate and numerous macrophages (C-upper panel). The Periodic Acid-Schiff staining showed small yeasts compatible with Histoplasma capsulatum, measuring 0.5 to 2.5 µm, within the cytoplasm of macrophages (arrows), with a clear halo (inset, arrows) (C-lower panel). These findings were compatible with esophageal histoplasmosis. Treatment was started with oral Itraconazole 400mg/day. After 3 months, a new UDE with biopsies showed complete esophageal healing. Gastrointestinal histoplasmosis manifests mainly in the small bowel and colon, related to a great amount of lymphoid tissue in these areas. Patients can present with fever, weight loss, abdominal pain and diarrhea. In endoscopy, we may find ulcerations, thickened wall, plaques and pseudopolyps2. It is considered a rare condition, and in only 3% of cases, there is esophageal involvement. This manifestation is mainly in immunosuppressed patients. It can be related to direct involvement of the esophagus or secondary to infiltration of mediastinal nodes2. In endoscopy, ulcerations, inflammatory masses, strictures, and external compressions can be found. This case illustrated the difficulty in differentiating early cancer from an esophageal histoplasmosis.

Background: Paracoccidioidomycosis (PCM) and histoplasmosis are endemic fungal diseases in South America. Both can lead to lung involvement with fungal dissemination progressing to systemic and severe clinical manifestations, especially in immunosuppressed hosts. As the population of immunosuppressed individuals has been rising, a higher occurrence of fungal infections is predicted in this setting. This poses challenges regarding the differential diagnosis due to overlapping clinical and laboratorial findings, hampering the management of cases., Objectives: In this study, the authors discuss the occurrence of a false-positive Histoplasma urinary antigen detection in a kidney transplant recipient with acute PCM. Given the scarce information about this subject, a review on literature data is provided., Methods: A comprehensive literature search was conducted to investigate previous studies that found cross-reactivity between Histoplasma urinary antigen assays in human patients with confirmed diagnosis of PCM. Additionally, an update of PCM in transplant recipients is provided., Findings: The included studies reported 120 samples from patients with PCM tested for Histoplasma antigen, presenting an overall cross-reactivity of 51.67% and 17 cases of PCM in transplant recipients. CONCLUSIONS: The galactomannan urinary antigen developed to diagnose histoplasmosis can cross react with PCM, which may represent a concern in countries where both mycoses overlap., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Oliveira Bastos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

A male in his 30s who was recently diagnosed with HIV arrived at the emergency department exhibiting an altered mental state and acute respiratory distress. Initial laboratory tests revealed a high anion gap metabolic acidosis, elevated liver enzyme levels and bicytopenia. A CT scan identified a miliary pattern. Bronchoscopy with bronchoalveolar lavage displayed epithelial and inflammatory cells. However, subsequent tests ruled out the presence of fungi, Pneumocystis organisms, malignancies, granulomas and viral inclusions. Broad-spectrum antibiotics with emphasis on Mycobacterium tuberculosis and antifungal treatments were administered. The regimen was adjusted after a positive urine test for the Histoplasma antigen.The patient later manifested signs and symptoms, including increased ferritin level, fever, splenomegaly, diminished natural killer cell function and heightened interleukin-2 receptor levels, confirming haemophagocytic lymphohistiocytosis. Given the patient's gravely decompensated state, the treatment incorporated dexamethasone, and the patient's vasopressor-resistant septic shock was addressed with methylene blue., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Histoplasmosis capsulatum is a dimorphic fungus, recognised for its endemic presence in multiple global regions. It may cause severe opportunistic disseminated infection in immunocompromised individuals. This is a case report of a 33-year-old man from Thailand who was admitted at a Danish hospital with fever, weight loss, cough, nosebleeds, and newly diagnosed HIV. The clinical condition rapidly deteriorated with lung and kidney failure. The patient was diagnosed with H. capsulatum fungaemia first detected on blood smear. He was treated with intravenous amphotericin B followed by oral itraconazole as well as antiretroviral therapy., (Published under Open Access CC-BY-NC-BD 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/.)

We present a case of a 56-year-old female with rheumatoid arthritis (RA) who has been on methotrexate for 9 years and has been complaining of high-grade fever for the past 1 month with no localizing signs and symptoms. She was thoroughly evaluated before being labeled as pyrexia of unknown origin. Histoplasmosis was suspected after bone marrow aspiration smear examination. The presence of histoplasma antigen in the urine confirmed our diagnosis. Fever responded after 2 weeks of liposomal amphotericin B and patient discharged in stable condition on tablet itraconazole., (© Journal of the Association of Physicians of India 2024.)

Central nervous system histoplasmosis is a serious complication of a common endemic mycosis, but it is rare in immunocompetent hosts. SARS-CoV-2 has introduced significant challenges into the healthcare setting with overlapping clinical presentations that may delay the diagnosis of alternative conditions. Additionally, it may lead to immune dysregulation and increase the risk for secondary infections, including invasive fungal diseases. Limited reports have described disseminated histoplasmosis in adults associated with COVID-19, but none have described central nervous system infection or complications in pediatric patients. We report a case of disseminated histoplasmosis involving the central nervous system in a previously healthy 13-year-old male with SARS-CoV-2 infection. An extensive immunological evaluation did not identify an underlying immunodeficiency. We highlight the potential of COVID-19 immune dys-regulation to contribute to the development or progression of invasive fungal disease. [ Pediatr Ann . 2024;53(8):e305-e309.] .

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.

Fingolimod is a sphingosine-1-phosphate receptor modulator used to treat multiple sclerosis. While fingolimod has been associated with an increased risk of cryptococcal meningitis, its correlation with other deep mycoses remains unclear. In this study, we conducted a scoping review of fingolimod associated with histoplasmosis, based on a case report, a literature review, and data from the FDA Adverse Events Reporting System (FAERS) as of January 24th, 2023. A 30-year-old Brazilian woman diagnosed with relapsing-remitting multiple sclerosis, receiving a daily dose of 0.5 mg of fingolimod, presented with a two-month history of fever and unintended weight loss, accompanied by lymphadenopathy, splenomegaly, and lung involvement was investigated. Biopsy of a lung nodule revealed fungal structures suggestive of Histoplasma sp. Additionally, serological testing yielded positive for Histoplasma capsulatum. Disseminated histoplasmosis should be considered in the differential diagnosis of febrile syndromes in patients undergoing fingolimod therapy for multiple sclerosis, particularly in the Americas, where this mycosis is endemic. Treatment with itraconazole and modification of immunotherapy can achieve excellent clinical outcomes.

Histoplasmosis presents a substantial clinical challenge globally, with a particular prevalence in South America, especially among patients with concurrent Human Immunodeficiency Virus (HIV) infection. Despite itraconazole's established efficacy, investigating alternative therapeutic approaches remains imperative. This is the largest study in our region to date, assessing the effectiveness of the less explored posaconazole treatment. This observational study, conducted at Fundación Valle del Lili (FVL) from 2016 to 2022, encompassed adults with disseminated histoplasmosis. Patients (n = 31) were treated with liposomal amphotericin B as an initial treatment, followed by consolidation treatment with posaconazole or itraconazole. Patients with single-organ cases, those lacking microbiological diagnosis, those who received initial treatment with antifungals other than liposomal Amphotericin B and those with < 6 months follow-up were excluded (Figure 1). Analyses considered population characteristics, treatments, and outcomes. Patients (average age: 45.6; 58.1% female) had common comorbidities (HIV 38.7%, solid organ transplantation 29% and oncologic disease 12.9%). Lungs (48.4%) and lymph nodes (16.1%) were commonly affected. Biopsy (64.5%) was the primary diagnostic method. Initial treatment with liposomal amphotericin B (100%) was given for 14 days on average. Follow-up indicated 71% completion with 19.4% requiring treatment modifications. Notably, 70.9% completed a posaconazole consolidation regimen over 350 days on average. Drug interactions during consolidation (80.6%) were common. No relapses occurred, and three deaths unrelated to histoplasmosis were reported. Traditionally, itraconazole has been the prevalent initial treatment; however, in our cohort, 55.9% of patients received posaconazole as the primary option. Encouragingly, posaconazole showed favorable tolerance and infection resolution, suggesting its potential as an effective and well-tolerated alternative for consolidation treatment. This finding prompts further exploration of posaconazole, potentially leading to more effective patient care and better outcomes., (© The Author(s) 2024. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

Antigen testing is an important diagnostic tool for histoplasmosis but has limited availability globally. We evaluated the OIDx urine lateral flow antigen assay among 204 persons suspected to have histoplasmosis. Among patients with proven histoplasmosis, sensitivity was 33.3% (3/9, 95% CI 7.5%-70.1%) and specificity 80.5% (157/195, 95% CI 74.3%-85.8%). The MiraVista urine antigen test had better specificity (96.9%) and equal sensitivity. The OIDx test demonstrated 33.3% (3/9) positive agreement and 84.0% (163/194) negative agreement with the MiraVista test. These results should be considered in the context of our low HIV prevalence population with a mixture of pulmonary and disseminated disease., (© The Author(s) 2024. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

Immunosuppressed patients can present with opportunistic infections resulting from an intrinsic systemic disease, which easily evolves into more aggressive and less common conditions. This work reports a clinical case of a female patient with histoplasmosis lesions in the nasal and oral mucosa, including pulmonary, hematological, and hepatic impairment, which led to the diagnosis of HIV seropositivity. In the presence of severe immunosuppression, morbidity is increased due to deep fungal infections and their unusual clinical characteristics can make diagnosis difficult. Therefore, it can be very helpful to recognize these clinical characteristics in order to determine early diagnostic interventions. It is important to recognize mucocutaneous manifestations of histoplasmosis because the biopsy of these lesions, and subsequent histopathological analysis, is one of the quickest, safest, and cheapest methods of diagnosis., (© 2024 Special Care Dentistry Association and Wiley Periodicals LLC.)

Background Itraconazole is the preferred azole for histoplasmosis in the current Infectious Diseases Society of America guidelines. Voriconazole is increasingly used as treatment for histoplasmosis; it has in vitro activity against Histoplasma capsulatum and has shown success in case reports and small case series, but may have a lower barrier to resistance. No comparative studies have been published. Methods We constructed a single-center, retrospective cohort of adult patients diagnosed with histoplasmosis from 2002 to 2017. Individual charts were reviewed to gather clinical information, including demographics, clinical features, immune status, treatments, and mortality. Patients were categorized based on the choice of azole and use as an initial treatment or as a step-down therapy from amphotericin B. Initial therapies with other azoles were excluded. Mortality was compared using a multivariable Cox proportional hazards with Heaviside function at 42 days. Results We identified 261 cases of histoplasmosis from 2002 to 2017. After excluding patients not treated with itraconazole or voriconazole, 194 patients remained. Of these, 175 (90%) patients received itraconazole and 19 (10%) received voriconazole. There were no significant demographic differences between patient populations receiving either azole as their initial azole treatment. Death at 180 days occurred in 41 patients (23.4%) in the itraconazole group and 6 patients (31.6%) in the voriconazole group. Patients on voriconazole had a statistically significant increase in mortality during the first 42 days after initiation of treatment when compared to patients receiving itraconazole (hazard ratio, 4.30; 95% confidence interval, 1.3–13.9; P =.015), when controlled for other risk factors. Conclusions Voriconazole in histoplasmosis was associated with increased mortality in the first 42 days when compared to itraconazole. [ABSTRACT FROM AUTHOR]

Disseminated histoplasmosis is a major cause of mortality in HIV-infected patients. Rapid and efficient diagnosis of Histoplasma capsulatum is crucial. Cytopathology is available in most hospitals and represents a rapid diagnostic alternative. In this study, we reviewed 12 years of experience to describe the cytology of histoplasmosis diagnosed by bronchoalveolar lavage (BAL) in relation to patient characteristics. BAL-diagnosed pulmonary histoplasmosis concerned 17 patients (14 HIV+). BAL cellularity ranged from 76,000 to 125,000 cells/mL in HIV patients, and 117,000 to 160,000 cells/mL in non-HIV patients. Macrophages predominated in all HIV patients (from 60% to 88%), lymphocytic infiltrates ranged from 5% to 15%, and neutrophils were very heterogeneous (from 2% to 32%). The number of H. capsulatum at hot spots seemed greater in HIV-infected than in immunocompetent patients (9 to 375 vs. 4 to 10) and were inversely proportional to the CD4 counts. Yeasts were both intracellular and extracellular in 85.7% of the HIV patients. This is the most comprehensive series detailing the cytological aspects of BAL in the diagnosis of H. capsulatum, focusing on the number of yeasts and their clustering pattern. The cytological examination of the Gomori-Grocott-stained BAL allows a reliable diagnosis of histoplasmosis. [ABSTRACT FROM AUTHOR]

Histoplasmosis is a systemic fungal disease caused by the pathogen Histoplasma spp. that results in significant morbidity and mortality in persons with HIV/AIDS and can also affect immunocompetent individuals. Although some PCR and antigen-detection assays have been developed, conventional diagnosis has largely relied on culture, which can take weeks. Our aim was to provide a proof of principle for rationally designing and standardizing PCR assays based on Histoplasmaspecific genomic sequences. Via automated comparisons of aligned genome contigs/scaffolds and gene (sub)sequences, we identified protein-coding genes that are present in existing sequences of Histoplasma strains but not in other genera. Two of the genes, PPK and CFP4, were used for designing primer sets for conventional and real-time PCR assays. Both resulted in a 100% analytical specificity in vitro and detected 62/62 H. capsulatum isolates using purified DNA. We also obtained positive detections of 2/2 confirmed H. capsulatum clinical FFPE (formalin-fixed paraffin-embedded) samples using both primer sets. Positive control plasmid 10-fold serial dilutions confirmed the analytical sensitivity of the assays. The findings suggest that these novel primer sets should allow for detection sensitivity and reduce false positive results/cross-reactions. New assays for detecting pathogenic fungi, constructed along these lines, could be simple and affordable to implement. [ABSTRACT FROM AUTHOR]

The classification of histoplasmosis as an AIDS-defining illness has largely attributed its occurrence in people to the presence of HIV/AIDS especially in Africa. Prior to the advent of the HIV/AIDS epidemic, many cases of histoplasmosis were documented both in the pediatric and adult population. Our review revealed 1461 reported cases of pediatric histoplasmosis globally in the last eight decades (1939–2021). North America (n = 1231) had the highest number of cases, followed by South America (n = 135), Africa (n = 65), Asia (n = 26) and Europe (n = 4). Histoplasmosis was much more common in the non-HIV pediatric population (n = 1418, 97.1%) compared to the HIV population. The non-HIV factors implicated were, childhood malignancies (n = 207), such as leukemias and lymphomas as well as their treatment, lung diseases (n = 7), environmental exposures and toxins (n = 224), autoimmune diseases (n = 12), organ transplants (n = 12), long-term steroid therapy (n = 3), the use of immunosuppressive drugs such as TNF-alpha inhibitors (n = 7) malnutrition (n = 12), histiocytosis (n = 3), hyperimmunoglobulin M and E syndromes (n = 15, 1.2%), pancytopaenias (n = 26), diabetes mellitus (n = 1) and T-cell deficiency (n = 21). Paediatricians should always consider or rule out a diagnosis of histoplasmosis in children presenting with symptoms suggestive of the above clinical conditions. [ABSTRACT FROM AUTHOR]

In areas where Histoplasma is endemic in the environment, occupations involving activities exposing workers to soil that contains bird or bat droppings may pose a risk for histoplasmosis. Occupational exposures are frequently implicated in histoplasmosis outbreaks. In this paper, we review the literature on occupationally acquired histoplasmosis. We describe the epidemiology, occupational risk factors, and prevention measures according to the hierarchy of controls. [ABSTRACT FROM AUTHOR]

Keywords: Conjunctival Granuloma; histoplasmosis with nocardiosis; nocardiosis; ocular histoplasmosis EN Conjunctival Granuloma histoplasmosis with nocardiosis nocardiosis ocular histoplasmosis 2689 2691 3 07/15/22 20220701 NES 220701 Histoplasmosis is a granulomatous infection caused by a dimorphic fungus Histoplasma capsulatum, found in old buildings, bird habitats, and bat caves. Conjunctival Granuloma, histoplasmosis with nocardiosis, nocardiosis, ocular histoplasmosis Since the patient was a diagnosed case of disseminated nocardiosis, the ocular lesion that occurred was also clinically suspected to reveal nocardia infection.{Figure 1} Anterior segment optical coherence tomography revealed superficial lesion with no scleral involvement. [Extracted from the article]

Progressive disseminated histoplasmosis (PDH) is thought to be on the top of the list of AIDS-defining illnesses in South America. Reported experience in children is very scarce. The aim of this study was to describe the clinical characteristics, management, and outcomes of children living with HIV presenting with PDH in Ecuador. We did a retrospective study using collected data on medical records of children living with HIV attended in Francisco Icaza Bustamante Children's Hospital (Guayaquil) between 1997 and 2019. The inclusion criteria consisted of patients under 18 years of age at admission with documented HIV infection and laboratory-confirmed diagnosis of PDH. Twenty-four children living with HIV were attended due to laboratory-confirmed PDH. Median CD4 cell count was 39 cells/mm³ (p25-p75 21-155) between 1 and 5 years and 22 cells/mm³ (p25-p75 10-57) for those aged 6 years and over. Fever (96%) was the most common clinical manifestation, followed by hepatomegaly (75%), cough (67%), weight loss (63%), diarrhea (63%), and abdominal distension (58%). Most significant laboratory findings were hypoalbuminemia (90%), hypertransaminasemia (78%), and pancytopenia (46%). Intravenous treatment with amphotericin B deoxycholate was started in all but one case in which diagnosis was postmortem. All these 23 patients were discharged after being hospitalized for a median of 68 days (p25-p75 48-90). Two children showed relapse during follow-up, one of whom died during the hospitalization of this second episode of PDH.Conclusion: Clinical manifestations and laboratory findings of PDH in children living with HIV seem similar to those seen in adults, and low CD4 cell count appears to be the most important risk factor. What is Known: • Since 1987, progressive disseminated histoplasmosis has been considered an AIDS-defining illness and, although underdiagnosis is frequent, is thought to be on the top of the list of AIDS-defining illnesses in South America. • Reported experience in children is very scarce. What is New: • Clinical manifestations and laboratory findings of progressive disseminated histoplasmosis in children living with HIV seem similar to those seen in adults. • Low CD4 cell count to be the most important risk factor. [ABSTRACT FROM AUTHOR]

Histoplasmosis is an uncommon opportunistic infection in human immunodeficiency virus (HIV) positive children. The most common form is primary disseminated histoplasmosis, characterized by persistent fever and failure to thrive. A 10-year-old HIV positive girl presented to the Baylor College of Medicine Children’s Foundation—Tanzania Mbeya Center of Excellence (COE) with ulcerated skin lesions and a violaceous facial rash. She also had persistent fevers, severe acute malnutrition, and severe anemia. At diagnosis, the patient was failing first line antiretroviral therapy (ART) with a cluster of differentiation 4 immune cells (CD4) of 24 cells/µL and an HIV viral load (VL)of196,658cp/mL. The patient was changed to a second line ART regimen (abacavir, lamivudine, and ritonavir-boosted lopinavir) and received nutritional support, blood transfusions, multiple antibiotics, and meticulous wound care. She also received comprehensive symptom management, psychosocial support, and emergency housing through the COE’s palliative care program. Biopsy of a lesion showed intracytoplasmic organisms consistent with Histoplasmosis capsulatum var capsulatum. The patient was treated with conventional amphotericin B and oral itraconazole and she achieved wound healing as well as immune reconstitution and HIV viral suppression. Amphotericin infusions were given as an outpatient despite the resource constraints of the setting in southwestern Tanzania. Histoplasmosis should be considered in the differential diagnosis of the immunocompromised host with unusual skin manifestations and persistent fever. [ABSTRACT FROM AUTHOR]

Histoplasmosis occurs predominantly in immunocompromised hosts and typically presents with mild constitutional symptoms, weight loss, weakness, fatigability, hepatosplenomegaly, and lymphadenopathy. The diagnosis is generally delayed and is based upon isolating the organism in blood cultures or by identifying intracellular organisms in tissues. Disseminated Histoplasmosis is well described in HIV patients but Histoplasmosis myositis is a rare manifestation and has not been reported in seronegative patients till date. We here address a case of a pharmacologically immunosuppressed patient with extensive Histoplasmosis myositis invading almost all the skeletal muscles of body (including plantar foot muscles) with no evidence of dissemination to other organ-systems. Clinical examination and investigations co-related with infiltrative muscle disease and skeletal muscle biopsy revealed Histoplasma capsulatum. This patient illustrates a distinctive clinical presentation of fungal infection with subtle constitutional symptoms and isolated muscle weakness which added to the diagnostic challenge. Hence, differential diagnosis of fungal infection must always be considered as a cause of myopathy in any pharmacologically immunosuppressed patient. [ABSTRACT FROM AUTHOR]

Histoplasmosis is a frequent cause of infections in people living with HIV/AIDS (PLWHA). This study introduces the application of a Histoplasma capsulatum urine antigen lateral flow assay (LFA) for diagnosing disseminated histoplasmosis in PLWHA in Suriname. The LFA's diagnostic accuracy was compared with the current diagnostic approach, aiming to assess whether this test resulted in improved early detection and management. Additionally, the prevalence of histoplasmosis among advanced stage HIV patients without clinical suspicion of infection was evaluated using the same LFA. In total, 98 patients were included in the study, of which 58 were classified as "possible disseminated histoplasmosis (DH)" based on clinical criteria and 40 as "controls". Of these possible DH cases, only 19 (32.7%) had a positive LFA. During the study, decisions for treatment were made without the treating physician being aware of the LFA result. Only 55% of the patients who started treatment for histoplasmosis based on clinical criteria had a positive LFA, and 21% of untreated patients had a positive LFA. This study shows that combining clinical signs with LFA results enhances diagnostic accuracy and is cost effective, resulting in better treatment decisions., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Woittiez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

BACKGROUND Histoplasma capsulatum is prevalent in the mid-eastern United States and is an environmental fungus that causes human infection by the inhalation of its spores. It is commonly associated with areas containing large amounts of bird excrement and can survive for years in the soil. Only 1% of infected individuals develop disseminated histoplasmosis or Histoplasma endocarditis. CASE REPORT A 61-year-old man with atrial fibrillation had 8 months of fatigue, low-grade fevers, night sweats, and unexplained weight loss presented to the Emergency Department. He worked and lived in Central Florida and although he raised cattle, he denied exposure to birds or bats with regularity. A transesophageal echocardiogram confirmed a sessile echo density on the atrial surface of the mitral valve. His microbial Karius cell-free DNA test from his blood sample was positive for Histoplasma capsulatum, and he was immediately given intravenous liposomal amphotericin for 2 weeks. A tissue valve was used to successfully replace his mitral valve along with a coronary artery bypass and a maze procedure for his persistent atrial fibrillation and atrial flutter. The diagnosis of mitral valve endocarditis from disseminated histoplasmosis was confirmed by pathological analysis, and he was sent home on long-term itraconazole maintenance treatment. CONCLUSIONS Surgical intervention in combination with anti-fungal medication can be a lifesaving intervention for disseminated histoplasmosis. A thorough history is particularly important when evaluating a patient with an unknown infectious source, especially assessing for risk factors, including exposure to environmental factors, workplace, and animals.

Objective: To determine the sensitivity and specificity of a commercial whole blood real-time PCR assay (RT-PCR) for the diagnosis of histoplasmosis when compared to direct organism identification and/or urine antigen quantification by enzyme immunoassay (UA-EIA). A secondary objective was to compare the sensitivity and specificity of RT-PCR to anti-Histoplasma immunoglobulin G antibody detection by enzyme immunoassay (IgG-EIA) and IgG-EIA to UA-EIA., Animals: Cats presented to the Kansas State University Veterinary Health Center from February through September of 2023 in which histoplasmosis was diagnosed or suspected., Methods: From February through September of 2023, cats were tested by RT-PCR, IgG-EIA, and UA-EIA if histoplasmosis was diagnosed cytologically or was a differential diagnosis for the presenting clinical signs. Cats were excluded if all 3 tests were not submitted or if the diagnosis of histoplasmosis could not be excluded despite a negative UA-EIA result. Cats with cytologically or histologically confirmed histoplasmosis were designated as proven histoplasmosis cases, and cats with a positive UA-EIA result without cytological or histological confirmation were designated as probable histoplasmosis cases., Results: 10 cats were diagnosed with either proven (n = 6) or probable (4) histoplasmosis, and 10 cats were considered true negatives. Whole blood RT-PCR results were negative in all 20 cats (sensitivity, 0%; 95% CI, 0% to 30.85%). The IgG-EIA was 90% sensitive (95% CI, 55.50% to 99.75%) and 70% specific (95% CI, 34.75% to 93.33%). The UA-EIA results were positive in all cats with proven histoplasmosis., Clinical Relevance: This commercial RT-PCR is insensitive when used on whole blood collected in EDTA and should not be used to diagnose feline histoplasmosis. Further studies are required to determine whether alternate RT-PCR protocols for EDTA-collected whole blood could be useful for diagnosing histoplasmosis in cats.