Histoplasmosis outbreaks in Venezuela: the silent burden of a neglected mycosis

Full abstract

Read the full abstract

Histoplasmosis outbreaks (HO) are linked to activities such as cave visits, construction, cleaning of abandoned buildings, tree felling, guano collection, mining, and speleology that disturb the environmental niche of Histoplasma capsulatum and aerosolize infectious propagules. Venezuela is endemic for histoplasmosis, with conditions for recurrent outbreaks. This report summarizes three urban outbreaks of acute pulmonary histoplasmosis (APH) diagnosed at the Medical Mycology Department “Dr. Dante Borelli” in 2007, 2016, and 2021, focusing on epidemiology, clinical presentation, diagnostic methods, and outcomes. The outbreaks were assessed through epidemiological surveys, clinical evaluation, imaging, conventional mycology, and serology. In 2021, Histoplasma Galactomannan Enzyme Immunoassay (HGM-EIA) was incorporated as an additional diagnostic tool. In 2007, 25 of 30 developed symptoms after an incubation period of 3–14 days, while five remained asymptomatic. In 2016, 13 schoolchildren were evaluated after an index case initially suspected of miliary tuberculosis led to an epidemiological investigation, linking the cases to soil and compost collection for tree planting at school. In 2021, twenty-one young adults aged 19–25 years were affected. The index case presented with prolonged fever and acute respiratory distress syndrome, was diagnosed by buffy coat examination, and improved after Amphotericin B treatment. Subsequent screening identified additional cases using HGM-EIA, with a mean urinary antigen concentration of 7.55 ng/mL. These outbreaks emphasize that acute pulmonary histoplasmosis may be underrecognized, especially after ecological disturbance or high-inoculum exposure. HGM-EIA improved outbreak detection, supporting earlier diagnosis, monitoring, and appropriate treatment.