Mapping Histoplasma spp. in bats and cave ecosystems: evidence from midwestern Brazil

Caves serve as natural reservoirs for diverse microbial species due to their unique biotic and abiotic conditions. Histoplasma spp. is frequently associated with guano-enriched soil, low luminosity, and high humidity, particularly in Latin America, a region highly endemic for histoplasmosis. Despite the continent's diverse biomes, local environmental and host distributions of Histoplasma remain poorly understood. To address this knowledge gap, we conducted a Histoplasma-specific quantitative PCR assay targeting the hc100 gene on guano samples from seven bat-inhabited caves and tissue samples from 74 bats of nine species in the Federal District of Brazil and surrounding regions. We detected Histoplasma DNA in 16 of 80 soil samples (20%) and in 33 bats representing seven species. Among 222 tissue samples (74 lung, 74 spleen, and 74 brain samples), 39 tested positive: 22 lung, 10 spleen, and 7 brain samples. Four bats had Histoplasma DNA in both lungs and brain, and two in both lungs and spleen. By mapping the presence of Histoplasma spp. across sampled caves, we identified environmental hotspots of fungal prevalence, emphasizing the need for targeted surveillance.

Our study provides critical insights into the environmental and host distribution of Histoplasma spp. in Brazil, identifying caves with high fungal prevalence and demonstrating its presence in multiple bat species. These findings underscore the necessity of public health interventions to mitigate the risk of histoplasmosis among cave visitors in the region. Additionally, we highlight the utility of quantitative PCR for detecting Histoplasma spp. in environmental and biological samples, supporting future epidemiological research in Latin America.