Treatment and Prevention of Histoplasmosis in Adults Living with HIV

Histoplasmosis causes life-threatening disseminated infection in adult patients living with untreated HIV. Although disease incidence has declined dramatically in countries with access to antiretroviral therapy, histoplasmosis remains prevalent in many resource-limited regions. A high index of suspicion for histoplasmosis should be maintained in the setting of a febrile multisystem illness in severely immunosuppressed patients, particularly in persons with hemophagocytic lymphohistiocytosis. Preferred treatment regimens for initial therapy include liposomal amphotericin B for severe disease, or itraconazole for mild to moderate disease. Subsequently, itraconazole maintenance therapy should be administered for at least one year and then discontinued if CD4 count increases to ≥150 cells/µL. Antiretroviral therapy, which improves outcome when administered together with an antifungal agent, should be instituted immediately, as the risk of triggering Immune Reconstitution Syndrome is low. The major risk factor for relapsed infection is nonadherence. Itraconazole prophylaxis reduces risk for histoplasmosis in patients with CD4 counts <100/µL but is not associated with survival benefit and is primarily reserved for use in outbreaks. Although most patients with histoplasmosis have not had recognized high-risk exposures, avoidance of contact with bird or bat guano or inhalation of aerosolized soil in endemic regions may reduce risk. Adherence to effective antiretroviral therapy is the most important strategy for reducing the incidence of life-threatening histoplasmosis.

Clinical and epidemiological characterization of histoplasmosis cases in a nonendemic area, Connecticut, United States

We performed a retrospective analysis of histoplasmosis cases diagnosed at our institution in New Haven, Connecticut, from 2005 to 2015. Among 12 cases of active histoplasmosis, seven were immunosuppressed and five had human immunodeficiency virus (HIV). Eleven patients reported travel to potentially endemic areas at a median of 105 days prior to presentation; travel to the Caribbean was most common (n = 6). Median time to diagnosis from symptom onset and first Histoplasma antigen testing were 41 and 28 days, respectively. Consistent with reports from other non-endemic areas, our findings suggest that the epidemiology of histoplasmosis may differ in Connecticut, potentially contributing to delayed diagnoses.

High Mortality and Coinfection in a Prospective Cohort of Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome Patients with Histoplasmosis in Guatemala

Histoplasmosis is one of the most common and deadly opportunistic infections among persons living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome in Latin America, but due to limited diagnostic capacity in this region, few data on the burden and clinical characteristics of this disease exist. Between 2005 and 2009, we enrolled patients ≥ 18 years of age with suspected histoplasmosis at a hospital-based HIV clinic in Guatemala City. A case of suspected histoplasmosis was defined as a person presenting with at least three of five clinical or radiologic criteria. A confirmed case of histoplasmosis was defined as a person with a positive culture or urine antigen test for Histoplasma capsulatum. Demographic and clinical data were also collected and analyzed. Of 263 enrolled as suspected cases of histoplasmosis, 101 (38.4%) were confirmed cases. Median time to diagnosis was 15 days after presentation (interquartile range [IQR] = 5-23). Crude overall mortality was 43.6%; median survival time was 19 days (IQR = 4-69). Mycobacterial infection was diagnosed in 70 (26.6%) cases; 26 (25.7%) histoplasmosis cases were coinfected with mycobacteria. High mortality and short survival time after initial symptoms were observed in patients with histoplasmosis. Mycobacterial coinfection diagnoses were frequent, highlighting the importance of pursuing diagnoses for both diseases.

The Hispanic HIV Epidemic

The Hispanic population in the U.S. has been dramatically affected by the HIV epidemic. The impact not only is related to the infection itself and its complications, but also is driven by social factors that lead to increased disparity in health-care access and cultural modeling and to increased social stigma, which leads to marginalization and exacerbates the existing gaps in medical care. Hispanics infected with HIV more frequently receive delayed diagnoses and more often present with AIDS, concomitant opportunistic infections, or coinfections related to their country of origin. The unique characteristics that define the HIV epidemic in Hispanics need further analysis in order to identify new opportunities to improve linkage to health care, increase efficacy in health-care provision, and decrease social disparities related to the Hispanic population.

α-Defensins in human innate immunity

Defensins are small, multifunctional cationic peptides. They typically contain six conserved cysteines whose three intramolecular disulfides stabilize a largely β-sheet structure. This review of human α-defensins begins by describing their evolution, including their likely relationship to the Big Defensins of invertebrates, and their kinship to the β-defensin peptides of many if not all vertebrates, and the θ-defensins found in certain non-human primates. We provide a short history of the search for leukocyte-derived microbicidal molecules, emphasizing the roles played by luck (good), preconceived notions (mostly bad), and proper timing (essential). The antimicrobial, antiviral, antitoxic, and binding properties of human α-defensins are summarized. The structural features of α-defensins are described extensively and their functional contributions are assessed. The properties of HD6, an enigmatic Paneth cell α-defensin, are contrasted with those of the four myeloid α-defensins (HNP1-4) and of HD5, the other α-defensin of human Paneth cells. The review ends with a decalogue that may assist researchers or students interested in α-defensins and related aspects of neutrophil function.