Blastomycosis in Indiana: Clinical and Epidemiological Patterns of Disease Gleaned from a Multicenter Retrospective Observational Study
Background: Though more commonly understood as endemic for histoplasmosis, Indiana is also highly prevalent for the fungus Blastomyces dermatitidis and is experiencing a rise in the incidence of blastomycosis. Major highway construction in the area was recently proposed as a contributing factor. Here, we aim to report on clinical and epidemiological patterns of blastomycosis in Indiana.
Methods: We conducted a retrospective chart review of microbiologically confirmed cases of blastomycosis from five hospitals serving central Indiana from 1985 to 2014. Available data were collected and analyzed. Data on population estimates, annual precipitation and construction projects in Indiana from 1990 to 2013 were obtained and evaluated for correlations with incidence rates of blastomycosis.
Results: A total of 114 patients were identified. The mean age was 44.4; 64.9% were males, 26.3% had diabetes mellitus and 15.8% were immunosuppressed. Most presented with pneumonia (90.4%); 44.7% had disseminated disease and 14.9% developed Acute Respiratory Distress Syndrome (ARDS). Extrapulmonary involvement most commonly involved the skin (46.0%) followed by bone (13.9%). Sensitivity of cultures, cytopathology and antigen detection were 86.0%, 46.0%, and 72.3% respectively. Amphotericin B was administered in 41.2% and 74.6% received an azole. In-hospital mortality was 9.6%. There was a substantial increase in incidence across time and a bimodal distribution from 2003 to 2013 (nadir in 2010) suggesting periodic disturbance. There was no correlation with amount of precipitation but the rise in incidence coincided with a 2005 state initiative to expand Indiana's highway infrastructure. There was a clustering of cases in Marion County but population increases did not fully account for the rise in incidence in the county.
Conclusion: Blastomycosis is highly prevalent in Indiana, mostly affects immunocompetent individuals and may lead to disseminated disease and ARDS. For reasons that are as of yet unclear, the incidence is rising. Making this disease reportable in Indiana will lead to increased awareness among local clinicians and a better understanding of the epidemiology of this endemic mycosis.
M. M. Azar,
R. Relich, None
B. Schmitt, None
S. Norris, None
L. Wheat, MiraVista Diagnostics: Employee, Salary
C. Hage, None