Mapping the Spread and Types of Fungal Infection in the US

Jenn Hoskins
14th March, 2024

Image Source: Natural Science News, 2024

Key Findings

Study from the University of Brasília found two main fungi, H. mississippiense and H. ohiense, cause histoplasmosis across the US
These fungi are more widespread than thought, with overlapping areas, suggesting a broader infection risk
The fungi prefer different climates: H. ohiense likes warm, dry areas; H. mississippiense thrives in cool, wet regions

Histoplasmosis is a serious infection caused by the fungus Histoplasma capsulatum, which can be found in certain soils. When people breathe in the microscopic fungal spores, they can develop this disease, which ranges from mild to potentially life-threatening. Traditionally, histoplasmosis has been associated with the Ohio and Mississippi River Valleys; however, a new study from the University of Brasília has shed light on the broader distribution and genetic diversity of the pathogen across the United States^[1]. The recent research analyzed 93 Histoplasma isolates, including 62 new genomes, from clinical, environmental, and veterinary samples. The whole-genome sequencing approach, coupled with evolutionary and species niche modeling analyses, revealed that there are two main lineages of the fungus causing histoplasmosis in the US: Histoplasma mississippiense and H. ohiense, with some sporadic cases caused by H. suramericanum in California and Texas. Previously, it was believed that histoplasmosis cases were confined to specific areas, but this study confirms that the two major Histoplasma species are more widespread, with overlapping geographic distributions in some regions. This indicates that the risk of infection may not be limited to traditionally recognized areas, as both species have been found to coexist in several locations. The study's species niche modeling gives us insight into the environmental preferences of each fungal species. H. ohiense appears to favor warmer, drier conditions, while H. mississippiense is more prevalent in cooler, wetter environments. This information can help predict where the fungus might thrive and where histoplasmosis cases could occur, potentially outside of the previously established endemic regions. This recent work builds upon previous studies that have shown an increase in histoplasmosis diagnoses outside the historically known endemic areas^[2]. The shifting geographic distribution of these fungi is also supported by another study that used public health surveillance data to estimate the latent presence of H. capsulatum, finding a northward shift in the endemic region around the Great Lakes^[3]. Additionally, genomic analyses have confirmed local acquisition of histoplasmosis in areas like Alberta, Canada, which was not traditionally considered a risk region^[4]. These findings all point to a dynamic and changing landscape for histoplasmosis risk. The genomic analysis in this study also suggests the possibility of gene exchange and hybridization between the two species in areas where they co-occur. This could have implications for the development of the fungus and its response to environmental pressures. It is important to note that this work represents the most comprehensive study of the genomic epidemiology of histoplasmosis in the US to date. In light of these findings, it is crucial for healthcare providers to consider histoplasmosis in patients with compatible symptoms, even if they have not traveled to known endemic areas. The study emphasizes the need for increased clinical suspicion and diagnostic testing to prevent missed or delayed diagnoses, which can lead to better patient outcomes. The understanding of Histoplasma's genetic diversity and distribution is further enhanced by high-quality genome assemblies that allow for detailed comparative analysis^[5]. These advanced genetic tools are helping researchers to map the evolutionary history of the pathogen and to understand its biology and interaction with the host. In conclusion, histoplasmosis is a more widespread health concern than previously recognized, with two major fungal species causing the disease across a wider geographical range in the United States. The findings from the University of Brasília's research provide valuable insights into the epidemiology of histoplasmosis and underscore the importance of considering this disease in a broader clinical and ecological context.

Health Genetics Mycology

References

Main Study

1) Tracing histoplasmosis genomic epidemiology and species occurrence across the USA.

Published 11th March, 2024

https://doi.org/10.1080/22221751.2024.2315960

Related Studies

2) The Geographic Distribution of Dimorphic Mycoses in the United States for the Modern Era.

https://doi.org/10.1093/cid/ciac882

3) Integrating Public Health Surveillance and Environmental Data to Model Presence of Histoplasma in the United States.

https://doi.org/10.1097/EDE.0000000000001499

4) Histoplasmosis acquired in Alberta, Canada: an epidemiological and genomic study.

https://doi.org/10.1016/S2666-5247(20)30229-9

5) Chromosome-Level Genome Assembly of a Human Fungal Pathogen Reveals Synteny among Geographically Distinct Species.

https://doi.org/10.1128/mbio.02574-21

Key Findings

References

Main Study

Related Studies

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