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

Abstract

Background The dimorphic mycoses (DM) of the United States, Histoplasma, Coccidioides, and Blastomyces, commonly known as endemic mycoses of North America (in addition to Paracoccidioides), are increasingly being diagnosed outside their historical areas of endemicity. Despite this trend, the maps outlining their geographical distributions have not been updated in more than half a century using a large, nationwide database containing individual patient-level data. Methods Retrospective analysis of >45 million Medicare fee-for-service beneficiaries from 1 January 2007 through 31 December 2016. Diagnoses of histoplasmosis, coccidioidomycosis, and blastomycosis were defined by International Classification of Diseases 9th/10th edition codes. Primary outcome was the incidence of histoplasmosis, coccidioidomycosis, and blastomycosis for each US county. Clinically meaningful thresholds for incidence were defined as 100 cases per 100,000 person-years cases for histoplasmosis and coccidioidomycosis and 50 cases for blastomycosis. Results There were 79,749 histoplasmosis, 37,726 coccidioidomycosis, and 6,109 blastomycosis diagnoses in unique persons from 2007-2016 across 3,143 US counties. Considering all US states plus Washington DC, 94% (48/51) had at least one county above the clinically relevant threshold for histoplasmosis, 69% (35/51) for coccidioidomycosis, and 78% (40/51) for blastomycosis. Conclusion Persons with histoplasmosis, coccidioidomycosis, and blastomycosis are diagnosed in significant numbers outside their historical geographic distributions established more than 50 years ago. Clinicians should consider DM diagnoses based on compatible clinical syndromes with less emphasis placed on patient’s geographic exposure. Increased clinical suspicion leading to a subsequent increase in DM diagnostic testing would likely result in fewer missed diagnoses, fewer diagnostic delays, and improved patient outcomes.

Blastomycosis in New England: 5 Cases and a Review

“…A recent analysis of a large dataset of Medicare fee-for-services beneficiaries showed that blastomycosis is being diagnosed more often outside of traditional areas of endemicity [ 22 ]. One possible explanation is the increased use of immunosuppressive therapies, which has led to a recent spike in blastomycosis cases in Quebec [ 11 ].…”

Was Coccidioides a Pre-Columbian Hitchhiker to Southcentral Washington?

“…Using Occam’s razor’s dictum that the simplest explanation is more likely to be correct, we propose that the SC-WA soil was contaminated via the travel, death and burial of an ancient human or domesticated animal from the central CA region of endemicity to SC-WA. Recent large-scale analyses of clinical cases have established the occurrence of human coccidiomycosis well outside known regions of endemicity ( 9 , 73 ) and, while nearly all such occurrences are likely travel-related, it is possible that other locales contaminated with Coccidioides will be identified. Should those sites be found, the application of the same type of analysis as described here may further shed light on the mechanism by which Coccidioides can spread from its ancestral southwestern sites to colonize other regions.…”

A Rapidly Expanding Chest Wall Mass in an Adolescent With COVID-19

“…Due to climate change, the geographic range of endemic mycoses is expanding in the United States, making it likely that increased numbers of cases of infection with these pathogens will be encountered in the future. 31…”