ADVANCES IN THE DIAGNOSIS OF HISTOPLASMOSIS: AN UPDATE INTO LABORATORY DIAGNOSIS OF HISTOPLASMA CAPSULATUM.

TOSCANINI, MARIA AGUSTINA; RODRIGUEZ LABOCCETTA, CAROLINA MARIEL; VIDELA GARRIDO, AGUSTIN; BRICEÑO FERNÁNDEZ, VICTOR; HERMIDA ALAVA, KATHERINE ; ETCHECOPAZ, ALEJANDRO; IOVANNITTI, CRISTINA; NUSBLAT, ALEJANDRO D.; CUESTAS, MARIA LUJAN

Histoplasmosis: From diagnosis to treatment

Nova Science Publishers, Inc.

Año: 2023;

Histoplasmosis is a life-threatening systemic infection caused by the thermallydimorphic fungal pathogen Histoplasma capsulatum, whose natural reservoirs arethought to be soil enriched with bird excreta and bat guano. Althought this disease ishighly endemic in the Americas, it has a worldwide distribution. Amongimmunocompetent individuals, histoplasmosis is mostly asymptomatic andspontaneously self-limited. However, histoplasmosis is responsible for importantmorbidity and mortality in patients with an acquired or congenital T cellular immunitydeficiency. In HIV-infected patients, its extrapulmonary or disseminated form, knownas progressive disseminated histoplasmosis (PDH), is an AIDS-defining illness,particularly in Latin America, where 15,000 new infections and 9,000 deaths areestimated to occur annually.Histoplasmosis diagnosis is still challenging since symptoms are nonspecific and maybe confused with other infections, particularly tuberculosis. Moreover, late diagnosisof PDH is associated with high mortality; thus, there is a major need for a rapiddiagnosis and the instauration of an appropriate pharmacological therapy. In thisregard, some progress has been recently achieved, such as the publication of WorldHealth Organization (WHO)/Pan American Health Organization guidelines for the diagnosis and management of PDH among patients living with HIV and the inclusionof Histoplasma antigen testing in the WHO list of Essential Diagnostics.Definitive diagnosis of histoplasmosis is achieved by culture and histopathology, butthese methods present some drawbacks, including limited sensitivity, the need forbiosafety level-3 laboratories, trained mycologysts, and a long turnaround time of upto several weeks for fungal isolation. The use of serologic assays for PDH diagnosis islimited by a low sensitivity in immunocompromised individuals. Despite some in-house DNA detection assays were developed and showed a satisfactory performancefor diagnosis, all of them lack proper standardization and validation.Diagnosis of PDH by detecting urine Histoplasma antigen has proven to be highlyuseful due to its high sensitivity. However, cross-reactivity with other related fungi iscommon with the currently available commercial tests. Moreover, these tests areexpensive and only performed in a few laboratories. The identification of novelprotein candidates and their recombinant production may offer high-quality reagentsthat cirvunvect the use of native antigens. The aim of this chapter is to describe theutility and drawbacks of the available diagnostic methods for histoplasmosis, and toreview the latest approaches to achieve rapid and accurate tests for diagnosing thisfungal disease.