Disseminated Histoplasmosis: Fighting a neglected killer of patients with advanced HIV disease in Latin America
Mathieu Nacher, Pierre Couppié, Loïc Epelboin, Félix Djossou, Magalie Demar, Antoine Adenis
Abstract
Histoplasmosis was first described in Panama in 1906 in a patient presenting miliary tuberculosislike symptoms. Histoplasma is largely present in the Americas but has been described in Africa; Europe; South, Southeast, and East Asia; and Australia. [2] The mycelial phase grows in guano-enriched soils, and aerosolized infectious microconidia can be inhaled. However, when the inoculum is massive it can lead to severe and potentially fatal acute infections. A small proportion of patients with underlying lung disease, may develop chronic fibrotic apical lung infiltrates and cavitation. In immunosuppressed persons, Histoplasma progressively spread to other organs causing a disseminated infection, which, when left untreated, is mostly fatal. They are clinically very similar to miliary and/or extrapulmonary tuberculosis, and differentiating between the two is thus difficult. [5] In addition, histoplasmosis-tuberculosis coinfections are relatively frequent. Serology is insufficiently sensitive in immunocompromized patients, and fungal culture is slow and may exceed one month. Depending on the level of immune suppression, the dissemination and severity of disseminated histoplasmosis will increase. [3] About 20% of disseminated forms are severe and require prompt diagnosis and treatment because they have high case fatality, often within days. Progressive disseminated histoplasmosis became an AIDS-defining infection in 1986. In the United States of America, where the presence of endemic histoplasmosis is well known, antigen detection tests, which allow to obtain rapid results, became available for clinicians in the late 1980s and liposomal amphotericin became available in 1998.