Clinical Presentation of Blastomycosis is Associated With Infecting Species, Not Host Genotype

Abstract

Objective: To determine if host genetics may be a risk factor for severe blastomycosis.Design: A cohort of patients who had contracted blastomycosis underwent targeted SNP (single nucleotide polymorphism) genotyping. The genetics of these patients were compared to a set of age and gender-matched controls and between patients with severe versus mild to moderate blastomycosis.Setting: The Marshfield Clinic Health System in central and northern WisconsinParticipants: Patients with a diagnosis of blastomycosis prior to 2017 were contacted for enrollment in this study. A phone hotline was also set up to allow interested participants from outside the Marshfield Clinic Health System to request enrollment.Methods: SNP frequency was assessed for significant differences between the patient cohort and controls and between patients with severe versus mild to moderate blastomycosis. We also tested the effect of Blastomyces species identified in clinical isolates on disease symptoms and severity.Results: No significant differences were found in SNP frequency between cases and controls or between those with severe or mild to moderate blastomycosis. We did detect significant differences in symptom frequency and disease severity by Blastomyces species.Conclusions: Our study did not identify any genetic risk factors for blastomycosis. Instead, the species of Blastomyces causing the infection had a significant effect on disease severity.

Keywords: Blastomycosis; Fungal infection; Host genetics.

Figure 1.

Flowchart of recruitment, enrollment, and study completion. Eligible patients were identified based on chart review in the Marshfield Clinic Health System, in addition to setting up a phone hotline for interested participants from other health systems. After exclusions and searching specifically for patients with clinical isolates available, 284 patients were contacted for enrollment. Of those contacted, 83% enrolled in our cohort. Within the cohort, 85% consented to SNP genotyping, and 51% had genotyped clinical isolates of Blastomyces.