Revising Conventional Wisdom About Histoplasmosis in the United States

Histoplasmosis in Solid Organ Transplantation

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. It has a broad global distribution with shifting epidemiology during recent decades. While in immunocompetent individuals infection is usually self-resolving, solid organ transplant recipients are at increased risk of symptomatic disease with dissemination to extrapulmonary tissue. Diagnosis of histoplasmosis relies on direct observation of the pathogen (histopathology, cytopathology, and culture) or detection of antigens, antibodies, or nucleic acids. All transplant recipients with histoplasmosis warrant therapy, though the agent of choice and duration of therapy depends on the severity of disease. In the present article, we describe the pathogenesis, epidemiology, clinical manifestations and management of histoplasmosis in solid organ transplant recipients.

The seroprevalence of anti-Histoplasma capsulatum IgG antibody among pulmonary tuberculosis patients in seven referral tuberculosis hospitals in Indonesia

BACKGROUND

Histoplasma capsulatum exposure is rarely suspected in Indonesia. Pulmonary histoplasmosis can occur simultaneously with pulmonary tuberculosis (TB) or as an alternative diagnosis in clinically-diagnosed TB patients with no microbiological evidence of TB. This study aimed to determine the seroprevalence of anti-H. capsulatum IgG antibody among pulmonary TB patients.

METHODOLOGY

This was a sub-study of 306 participants from a prospective cohort pulmonary TB study conducted at seven TB referral hospitals in Indonesia. The study population was presumptive pulmonary TB adult patients who underwent microbiological TB examinations and were categorized as drug-sensitive (DS), drug-resistant (DR), and clinically-diagnosed TB. Anti-H. capsulatum IgG antibody levels at baseline were measured using MVista Histoplasma Ab enzyme immunoassays. Data were summarized using descriptive statistics. Bivariate and multivariate logistic regression analysis were performed to assess factors associated with anti-H. capsulatum IgG antibody positive result.

RESULTS

12.7% (39/306) of pulmonary TB patients were positive for anti-H. capsulatum IgG antibodies (DR-TB patients (15.9%, 18/114), DS-TB (13.0%, 15/115), and clinically-diagnosed TB (7.8%, 6/77)). The median unit value of anti-H. capsulatum IgG antibody for all positive samples was 15.7 (IQR 10.2-28.9) EU. This median unit value was higher in clinically-diagnosed TB patients compared to DS-TB or DR-TB patients (38.1 (IQR 25.6-46.6) EU, 19.7 (IQR 12.3-28.9) EU, and 10.9 (IQR 9.2-15.4), respectively). There were 10 patients (3.3%) with anti-H. capsulatum IgG antibody levels above 30 EU. Factors associated with the anti-H. capsulatum IgG antibody positive result were malignancies (OR 4.88, 95% CI 1.09-21.69, p = 0.037) and cavitary lesions (OR 2.27, 95% CI 1.09-4.70, p = 0.028).

CONCLUSIONS

Our results provide evidence of exposure to H. capsulatum among pulmonary TB patients in Indonesia. Further studies are needed to provide a comprehensive picture of this fungal disease in other populations and regions to enhance awareness among clinicians and public health officials.

Factors related to mortality in critically ill histoplasmosis: a multicenter retrospective study in Guadeloupe and French Guyana

PURPOSE

To describe clinical and biological features and the outcomes of patients admitted for histoplasmosis in two intensive care units (ICU) in French Guyana and in the French West Indies (Guadeloupe).

METHODS

All patients admitted to these two ICUs for culture-proven histoplasmosis between January 2014 to August 2022 were included in the study. Using univariate and multivariate analysis, we assessed risk factors at ICU admission that were associated with death.

RESULTS

Forty patients were included (65% men). Median age was 56 years and simplified acute physiologic score (SAPS) II was 65. HIV was found in 58%, another immunodeficiency was identified in 28%, and no underlying immunodeficiency could be identified in 14% of patients. Within the first 24 h of ICU admission, 85% of patients had acute respiratory failure, 78% had shock, 30% had coma, and 48% had hemophagocytic lymphohistiocytosis. Mechanical ventilation was instituted in 78% of patients and renal replacement therapy in 55%. The 30-day mortality was 53%. By multivariate analysis, factors independently associated with 30-day mortality were SOFA score (odds ratio [OR] 1.5, 95% confidence interval [CI] [1.1-2.1]), time between symptom onset and treatment per day (OR 1.1, 95% CI 1.0-1.1), and hemophagocytic lymphohistiocytosis (OR 6.4, 95% CI 1.1-47.5).

CONCLUSION

Histoplasmosis requiring ICU admission is a protean disease with multiple and severe organ involvement. Immunodeficiency is found in most patients. The prognosis remains severe despite appropriate treatment and is worsened by late treatment initiation.

Histoplasmosis of the External Auditory Canal

This report describes the diagnosis and treatment of a patient with a rare fungal infection of the external ear, as well as a review of the literature. A 76-year-old Caucasian gentleman from rural southern United States with diabetes and hypertension was referred to our clinic for intractable left otalgia, otorrhea, headaches, and an exophytic lesion in the left external ear since five months. There was no pertinent travel history. Biopsy by an outside otolaryngologist was inconclusive. Repeat biopsy under anesthesia revealed morphological characteristics consistent with histoplasmosis. Intravenous amphotericin B and later oral antifungal agent voriconazole led to improvement in symptoms. The clinical presentation resembled a malignancy. A high index of clinical suspicion, histologic confirmation with deep tissue biopsy, and culture are essential for diagnostic confirmation followed by treatment with systemic antifungals. A multidisciplinary team approach is necessary to manage this rare condition.

Disseminated Histoplasmosis Found in Bone Marrow in a Newly Diagnosed AIDS Patient: A Literature Review and Report of a Rare Case

Histoplasmosis is a rare fungal infection caused by the dimorphic species Histoplasma (H.) capsulatum, found in the Midwest and Central United States. Infection with H. capsulatum is observed in other regions beyond the Ohio and Mississippi River valley, including Mexico and Central and South America. There have been increasing reports of the disease occurring in Latin America in immunocompromised patients with human immunodeficiency virus (HIV). This case report details clinical findings of disseminated histoplasmosis in an immunocompromised patient, newly diagnosed with acquired immunodeficiency syndrome (AIDS) and initially presenting with sepsis of unclear source. The focus of this case report is the significance of detailed history-taking guiding for an appropriate investigation and recognition of the infectious source and giving insight into the management of disseminated histoplasmosis in the outpatient and inpatient settings.

Updates on Histoplasmosis in Solid Organ Transplantation

Purpose of Review

Recent Findings

Summary

Vaccines to Prevent Coccidioidomycosis: A Gene-Deletion Mutant of Coccidioides Posadasii as a Viable Candidate for Human Trials

Coccidioidomycosis is an endemic fungal infection that is reported in up to 20,000 persons per year and has an economic impact close to $1.5 billion. Natural infection virtually always confers protection from future exposure, and this suggests that a preventative vaccine strategy is likely to succeed. We here review progress toward that objective. There has been ongoing research to discover a coccidioidal vaccine over the past seven decades, including one phase III clinical trial, but for reasons of either efficacy or feasibility, a safe and effective vaccine has not yet been developed. This review first summarizes the past research to develop a coccidioidal vaccine. It then details the evidence that supports a live, gene-deletion vaccine candidate as suitable for further development as both a veterinary and a human clinical product. Finally, a plausible vaccine development plan is described which would be applicable to this vaccine candidate and also useful to other future candidates. The public health and economic impact of coccidioidomycosis fully justifies a public private partnership for vaccine development, and the development of a vaccine for this orphan disease will likely require some degree of public funding.