Histoplasmosis Outbreaks in Brazil: Lessons to Learn About Preventing Exposure.

Histoplasmosis is considered the most common invasive opportunistic fungal disease in the Americas, with outbreaks and micro-epidemics reported for over 80 years. In Brazil, this disease has been described since 1946, reaching a remarkable incidence in the population, especially during the HIV-AIDS pandemic. In this study, published and unpublished outbreaks and micro-epidemics of histoplasmosis in Brazil were revisited by accessing different database sources and evaluating epidemiological and clinical features. We have found reports spanning 1946-2017, across 10 Brazilian states and with involvement of 370 humans and 2 dogs, and 13 disseminated cases and 3 deaths were reported. Rio de Janeiro had the largest number of outbreaks (n = 20/40; 50%) reported in this study. The majority of outbreaks and micro-epidemics was reported in caves (n = 21/40; 52.5%), followed by reports in abandoned/deactivated sites (n = 6/40; 15%), mines (n = 5/40; 12.5%), chicken coops (n = 4/40; 10%). Histoplasmosis is a serious health issue in Brazil considering the attractive and growing market of ecotourism throughout more than 7000 caves, and all levels of poultry farming activity are important to raise awareness about how dangerous this neglected disease can be and establish ways to decrease exposure to contaminated environmental sources through adequate preventive measures.

Modification of the Francis Medium for the Conversion of Histoplasma capsulatum to the Yeast-Like Growth Phase.

We propose a modification of Francis agar used for identification of the causative agent of histoplasmosis by in vitro conversion of the mycelial culture to the yeast-like growth phase. For improving of the growth characteristics of the medium, we used FT-agar with glucose-vitamin additives developed for culturing of the tularemia causative agent. The modified Francis medium is characterized by significantly higher growth properties and allowed 10-fold increasing the number of CFU of yeast-like cells of both American and African histoplasmosis causative agent.

Vaccination with an alkaline extract of Histoplasma capsulatum packaged in glucan particles confers protective immunity in mice.

Infection with the dimorphic fungus, Histoplasma capsulatum, occurs world-wide, but North and South America are regions of high endemicity. Interventions to mitigate exposure and consequent disease are limited to remediating a habitat harboring the fungus. The development of a vaccine to prevent infection or lessen its severity is an important advance in disease prevention. Accordingly, we prepared an alkaline extract from the yeast phase of Histoplasma and encased it in glucan particles that act as an adjuvant and delivery vehicle. Immunization of C57BL/6 mice with this encapsulated extract decreased the number of CFUs in lungs and spleens at days 7 and 14 following intranasal infection. Moreover, this vaccine conferred protection against a lethal challenge with the fungus. Cytokine assessment in lungs at a time when the CFUs were similar between controls and vaccinated groups revealed increased quantities of interferon-γ and interleukin-17 in vaccine recipients. This finding was supported by increased generation of both Th1 and Th17 cells in lungs and draining lymph nodes of vaccinated mice compared to controls. Neutralization of interferon-γ or interleukin-17 blunted the effectiveness of vaccination. To identify the proteins comprising this extract, liquid chromatography tandem mass spectrometry was performed. Thus, an H. capsulatum alkaline extract packaged in glucan particles confers protection in an interferon-γ and interleukin-17-dependent manner. Discovery of a single protein or a few proteins in this admixture that mediate protective immunity would represent significant progress in efforts to prevent histoplasmosis.

[Efficacy of the treatment and secondary antifungal prophylaxis in AIDS-related histoplasmosis. Experience at the Francisco J. Muñiz Infectious Diseases Hospital in Buenos Aires]. / Eficacia del tratamiento y de la profilaxis antifúngica secundaria en la histoplasmosis asociada al sida. Experiencia del Hospital de Infecciosas Francisco J. Muñiz, de la ciudad de Buenos Aires.

BACKGROUND: Classic histoplasmosis is a systemic endemic mycosis due to Histoplasma capsulatum var. capsulatum. A significant reduction in the morbidity and mortality of AIDS-related histoplasmosis has been observed since the introduction of highly active antiretroviral therapy (HAART) and secondary antifungal prophylaxis. AIMS: The aim of this study was to determine the current state of prognosis and treatment response of HIV-positive patients with histoplasmosis in the Francisco J. Muñiz Infectious Diseases Hospital in Buenos Aires City. METHODS: A retrospective study was conducted using the demographic, clinical, immunological and treatment data of 80 patients suffering from AIDS-related histoplasmosis. RESULTS: Of the 80 cases studied 65 were male, the median age was 36 years, with 73.7% of the patients being drug addicts, 82.5% of the patients was not receiving HAART at diagnosis, and 58.7% of the cases had less than 50 CD4+ cells/µl at the beginning of the treatment. The initial phase of treatment consisted of intravenous amphotericin B and/or oral itraconazole for 3 months, with 78.7% of the cases showing a good clinical response. Only 26/63 patients who were discharged from hospital continued with the follow-up of the HAART, secondary prophylaxis with itraconazole or amphotericin B. Secondary prophylaxis was stopped after more than one year of HAART if the patients were asymptomatic, had two CD4+ cell counts greater than 150cells/µl, and undetectable viral loads. No relapses were observed during a two-year follow up after prophylaxis was stopped. CONCLUSIONS: The treatment of histoplasmosis in HIV-positive patients was effective in 78.8% of the cases. The combination of HAART and secondary antifungal prophylaxis is safe, well tolerated, and effective. The low adherence of patients to HAART and the lack of laboratory kits for rapid histoplasmosis diagnosis should be addressed in the future. The usefulness of primary antifungal prophylaxis for cryptococcosis and histoplasmosis HIV-positive patients should be studied.

Histoplasmosis in patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS): multicenter study of outcomes and factors associated with relapse.

Although discontinuation of suppressive antifungal therapy for acquired immunodeficiency syndrome (AIDS)-associated histoplasmosis is accepted for patients with immunologic recovery, there have been no published studies of this approach in clinical practice, and minimal characterization of individuals who relapse with this disease. We performed a multicenter retrospective cohort study to determine the outcome in AIDS patients following discontinuation of suppressive antifungal therapy for histoplasmosis. Ninety-seven patients were divided into a physician-discontinued suppressive therapy group (PD) (38 patients) and a physician-continued suppressive therapy group (PC) (59 patients). The 2 groups were not statistically different at baseline, but at discontinuation of therapy and at the most recent follow-up there were significant differences in adherence to therapy, human immunodeficiency virus (HIV) RNA, and urinary Histoplasma antigen concentration. There was no relapse or death attributed to histoplasmosis in the PD group compared with 36% relapse (p < 0.0001) and 5% death (p = 0.28) in the PC group. Relapse occurred in 53% of the nonadherent patients but not in the adherent patients (p < 0.0001). Sixty-seven percent of patients with initial central nervous system (CNS) histoplasmosis relapsed compared to 15% of patients without CNS involvement (p = 0.0004), which may be accounted for by nonadherence. In addition, patients with antigenuria above 2.0 ng/mL at 1-year follow-up were 12.82 times (95% confidence interval, 2.91-55.56) more likely to relapse compared to those with antigenuria below 2.0 ng/mL. Discontinuation of antifungal therapy was safe in adherent patients who completed at least 1 year of antifungal treatment, and had CD4 counts >150 cells/mL, HIV RNA <400 c/mL, Histoplasma antigenuria <2 ng/mL (equivalent to <4.0 units in second-generation method), and no CNS histoplasmosis.

C-type lectin receptors differentially induce th17 cells and vaccine immunity to the endemic mycosis of North America.

Vaccine immunity to the endemic mycoses of North America requires Th17 cells, but the pattern recognition receptors and signaling pathways that drive these protective responses have not been defined. We show that C-type lectin receptors exert divergent contributions to the development of antifungal Th17 cells and vaccine resistance against Blastomyces dermatitidis, Histoplasma capsulatum, and Coccidioides posadasii. Acquired immunity to B. dermatitidis requires Dectin-2, whereas vaccination against H. capsulatum and C. posadasii infection depends on innate sensing by Dectin-1 and Dectin-2, but not Mincle. Tracking Ag-specific T cells in vivo established that the Card9 signaling pathway acts indispensably and exclusively on differentiation of Th17 cells, while leaving intact their activation, proliferation, survival, and migration. Whereas Card9 signaling is essential, C-type lectin receptors offer distinct and divergent contributions to vaccine immunity against these endemic fungal pathogens. Our work provides new insight into innate immune mechanisms that drive vaccine immunity and Th17 cells.

Primary prophylaxis of disseminated histoplasmosis in HIV patients in French Guiana: arguments for cost effectiveness.

Histoplasmosis is the first cause of acquired immunodeficiency syndrome (AIDS) and AIDS-related deaths in French Guiana. Cohort data were used to determine whether primary prophylaxis with 100 mg itraconazole for patients with CD4 counts < 150/mm(3) was cost-effective with different scenarios. For a scenario where 12% of patients died, 60% were aware of their human immunodeficiency virus (HIV) infection and adherence was only 50%, primary prophylaxis would prevent 1 death and 9 cases of histoplasmosis for a cost of 36,792 Euros per averted death, 1,533 per life-year saved, 4,415 Euros per averted case, when only counting the costs of itraconazole prophylaxis. Taking into account the total costs of hospitalization showed that primary prophylaxis would allow a savings of 185,178 Euros per year. Even in a scenario of low adherence, primary prophylaxis would be cost-effective in French Guiana, and presumably in the rest of the Guianas and the Amazon.

Safety issues in vasculitis: infections and immunizations in the immunosuppressed host.

Infectious diseases are a significant cause of morbidity and mortality in immunosuppressed patients, including those with connective tissue diseases. Both disease and treatment contribute to a predisposition to infection in immunocompromised patients. Significant infection and morbidity occur in 25% to 50% of these patients with a median mortality of 5.2% due to common bacterial infections, such as pneumonia or bacteremia, and opportunistic fungal infections such as Pneumocystis. The lungs, skin, urinary tract, blood, and central nervous system are commonly affected. Pathogens such as Pneumocystis jirovecii, Histoplasma capsulatum, Aspergillus species, herpes zoster, JC virus, Nocardia asteroides, and Nocardia species are increasingly prevalent in immunocompromised patients. Improved recognition, diagnosis, and prevention of these infections are needed to enhance outcomes in these patients.

Pulmonary histoplasmosis.

Pulmonary histoplasmosis is an important cause of morbidity in the United States. Several outbreaks of acute pulmonary histoplasmosis have been linked to potentially preventable environmental exposures. Progressive disseminated histoplasmosis, which is seen frequently in the growing population of immunocompromised hosts, often presents with prominent pulmonary manifestations and is more commonly encountered in hospitalized patients than acute, subacute, or chronic pulmonary histoplasmosis. A battery of diagnostic studies including serology, antigen, cytology/histopathology, and culture should be obtained in suspected cases of histoplasmosis. The yield of antigenuria detection is highest when the multiple body fluids are tested; the level of antigenuria correlates with severity of disease. Amphotericin B is the treatment of choice for severe pulmonary or disseminated histoplasmosis, and itraconazole is effective for mild to moderately severe infection. Posaconazole exhibits promise as a salvage agent. Antifungal prophylaxis is not routinely recommended for at-risk populations. Measures to minimize environmental contamination may reduce the risk of epidemic-type acute pulmonary histoplasmosis related to high-risk exposures.

Immunization with apoptotic phagocytes containing Histoplasma capsulatum activates functional CD8(+) T cells to protect against histoplasmosis.

We have previously revealed the protective role of CD8(+) T cells in host defense against Histoplasma capsulatum in animals with CD4(+) T cell deficiency and demonstrated that sensitized CD8(+) T cells are restimulated in vitro by dendritic cells that have ingested apoptotic macrophage-associated Histoplasma antigen. Here we show that immunization with apoptotic phagocytes containing heat-killed Histoplasma efficiently activated functional CD8(+) T cells whose contribution was equal to that of CD4(+) T cells in protection against Histoplasma challenge. Inhibition of macrophage apoptosis due to inducible nitric oxide synthase (iNOS) deficiency or by caspase inhibitor treatment dampened the CD8(+) T cell but not the CD4(+) T cell response to pulmonary Histoplasma infection. In mice subcutaneously immunized with viable Histoplasma yeasts whose CD8(+) T cells are protective against Histoplasma challenge, there was heavy granulocyte and macrophage infiltration and the infiltrating cells became apoptotic. In mice subcutaneously immunized with carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled apoptotic macrophages containing heat-killed Histoplasma, the CFSE-labeled macrophage material was found to localize within dendritic cells in the draining lymph node. Moreover, depleting dendritic cells in immunized CD11c-DTR mice significantly reduced CD8(+) T cell activation. Taken together, our results revealed that phagocyte apoptosis in the Histoplasma-infected host is associated with CD8(+) T cell activation and that immunization with apoptotic phagocytes containing heat-killed Histoplasma efficiently evokes a protective CD8(+) T cell response. These results suggest that employing apoptotic phagocytes as antigen donor cells is a viable approach for the development of efficacious vaccines to elicit strong CD8(+) T cell as well as CD4(+) T cell responses to Histoplasma infection.

Imágenes de histoplasmosis ano-rectal en pacientes con SIDA / Images anorectal histoplasmosis in AIDS patients

Paciente masculino quien presenta sintomatología de estreñimiento y hematoquezia de 2 meses de evolución a quien se le realiza proctosigmoidoscopía en donde se evidencia ulceras probablemente de tipo infeccioso y toman biopsia, posteriormente es diagnosticado con SIDA e inician tx.Arv. Y por resultado de biopsia la cual con presencia de histoplasma se inicia tratamiento con itraconazol, posteriormente paciente con FNCxT, por lo cual se ingresa a Hospital Roosevelt en donde se inicia tratamiento con Anfotericina B respondiendo faborablemente...

Passive administration of monoclonal antibodies against H. capsulatum and other fungal pathogens.

The purpose of the use of this methodology is 1) to advance our capacity to protect individuals with antibody or vaccine for preventing or treating histoplasmosis caused by the fungus Histoplasma capsulatum and 2) to examine the role of virulence factors as target for therapy. To generate mAbs, mice are immunized, the immune responses are assessed using a solid phase ELISA system developed in our laboratory, and the best responder mice are selected for isolation of splenocytes for fusion with hybridoma cells. C57BL/6 mice have been extensively used to study H. capsulatum pathogenesis and provide the best model for obtaining the data required. In order to assess the role of the mAbs in infection, mice are intraperitoneally administered with either mAb to H. capsulatum or isotype matched control mAb and then infected by either intravenous (i.v.), intraperitoneal (i.p.), or intranasal (i.n.) routes. In the scientific literature, efficacy of mAbs for fungal infections in mice relies on mortality as an end point, in conjunction with colony forming units (CFU) assessments at earlier time points. Survival (time to death) studies are necessary as they best represent human disease. Thus, efficacy of our intervention would not adequately be established without survival curves. This is also true for establishing efficacy of vaccine or testing of mutants for virulence. With histoplasmosis, the mice often go from being energetic to dead over several hours. The capacity of an intervention such as the administration of a mAb may initially protect an animal from disease, but the disease can relapse which would not be realized in short CFU experiments. In addition to survival and fungal burden assays, we examine the inflammatory responses to infection (histology, cellular recruitment, cytokine responses). For survival/time to death experiments, the mice are infected and monitored at least twice daily for signs of morbidity. To assess fungal burden, histopathology, and cytokine responses, the mice are euthanized at various times after infection. Animal experiments are performed according to the guidelines of the Institute for Animal Studies of the Albert Einstein College of Medicine.

HIV-associated histoplasmosis in a nonendemic area of the United States during the HAART era: role of migration from endemic areas and lack of antiretroviral therapy.

Histoplasmosis is known to be an AIDS-associated infection, with scattered areas of endemicity throughout the world. Although the Atlanta, GA, metropolitan area is not a highly endemic area, a significant number of cases have been noted at our institution in recent years. Cases of histoplasmosis over a 4-year period were reviewed. All 27 patients (100%) were HIV infected. Thirty percent of patients with histoplasmosis were from Latin American countries. Patients from Latin America were younger than patients from the United States, tended to be more likely to have proven disease, and were exclusively male. Patients with proven disease had significantly higher urine histoplasma antigen levels, lower platelets counts, and lower neutrophil counts than patients with probable disease. The majority of patients survived after treatment with antifungals and initiation of antiretroviral therapy. Histoplasmosis is thus an important consideration in the workup of patients with advanced HIV in nonendemic areas of the United States.

Recognition, diagnosis, and treatment of histoplasmosis complicating tumor necrosis factor blocker therapy.

Life-threatening histoplasmosis is one of the most common opportunistic infections in patients receiving tumor necrosis factor (TNF) blockers. Delays in considering the diagnosis may lead to increased morbidity and mortality. Most affected patients present with pneumonitis, usually accompanied by additional signs of progressive dissemination, or with signs of progressive dissemination alone. The diagnosis often can be promptly established using antigen detection or direct examination of bronchoalveolar lavage specimens. If histoplasmosis is diagnosed promptly, antifungal therapy is highly effective. After a favorable clinical response, the safety of both discontinuation of antifungal therapy and the resumption of TNF blocker remains undetermined. The management of the immune reconstitution inflammatory syndrome that may follow discontinuation of TNF blockers also requires investigation. Prescribers should become aware of the recognition, diagnosis, and treatment of histoplasmosis and educate recipients about decreasing their risk of exposure and both recognizing and reporting signs of early infection.