Mapping Histoplasma capsulatum Exposure, United States

Area of Science:

• Environmental science
• Epidemiology
• Mycology

Background:

• Historical Histoplasma capsulatum prevalence maps are outdated due to significant environmental and land-use changes over 50 years.
• Recent outbreaks in Montana and Nebraska indicate a potential geographic shift in Histoplasma capsulatum distribution.
• Updated prevalence data are crucial for understanding current disease risk and distribution.

Purpose of the Study:

• To develop an updated geographic suitability model for Histoplasma capsulatum.
• To assess the current geographic distribution of Histoplasma capsulatum.
• To evaluate the model's predictive accuracy against existing histoplasmosis incidence data.

Main Methods:

• A weighted overlay geographic suitability model was created using a geographic information system.
• Satellite imagery data integrated land cover use (70%), distance to water (20%), and soil pH (10%).
• Logistic regression modeling compared the suitability map with Centers for Medicare and Medicaid Services histoplasmosis incidence data.

Main Results:

• The developed model showed moderate predictive accuracy for states with high and mid-to-high histoplasmosis incidence.
• Preferred soil environments for Histoplasma capsulatum have demonstrably migrated into the upper Missouri River basin.
• The study identified a northward shift in the suitable habitat for Histoplasma capsulatum.

Conclusions:

• Geographic suitability mapping is a valuable tool for updating infectious disease prevalence maps.
• Environmental changes necessitate ongoing reassessment of pathogen distribution and disease risk.
• The methodology may be applicable to modeling other geographically specific infectious agents.