Blastomycosis in northwestern Ontario, 2004 to 2014

Diagnostic Methods and Risk Factors for Severe Disease and Mortality in Blastomycosis: A Retrospective Cohort Study

Background: Blastomycosis can cause severe disease with progressive respiratory failure and dissemination even in immunocompetent individuals. We sought to evaluate risk factors for severe disease and mortality using clinical and laboratory data within a large health system in an endemic area. Methods: We performed a retrospective cohort study of patients diagnosed with blastomycosis at all Mayo Clinic sites from 1 January 2004 through 31 March 2020. Diagnosis was established by culture, histopathology/cytopathology, serology, antigen testing, or PCR. Disease was categorized as mild for patients treated in the outpatient setting, moderate for hospitalized patients who did not require intensive care, and severe for patients admitted to the intensive care unit. Logistic regression was used to evaluate risk factors for severe disease. A Cox proportional hazards model was constructed to evaluate mortality. Findings: We identified 210 patients diagnosed with blastomycosis. Mean age was 51 years (range, 6–84). Most subjects were male (71.0%). Extrapulmonary disease was confirmed in 24.8%. In this cohort, 40.5% of patients had mild disease, 37.6% had moderate disease, and 21.9% had severe disease. Independent risk factors for severe disease were neutrophilia (odds ratio (OR) 3.35 (95% CI 1.53–7.35), p = 0.002) and lymphopenia (OR 3.34 (95% CI 1.59–7.03), p = 0.001). Mortality at 90 days was 11.9%. Median time from diagnosis to death was 23 days (interquartile range 8–31 days). Independent risk factors for mortality were age (OR 1.04 (95% CI 1.01–1.08), p = 0.009), neutrophilia (OR 2.84 (95% CI 1.04–7.76), p = 0.041), and lymphopenia (OR 4.50 (95% CI 1.67–12.11), p = 0.003). Blastomyces immunodiffusion had an overall sensitivity of 39.6% (95% CI 30.1–49.8). Sensitivity was higher among those who were tested 4 weeks or longer after the onset of symptoms. Urine Blastomyces antigen had a significantly higher sensitivity of 80.8% (95% CI 68.1–89.2) compared to serology. There was a trend towards higher antigen concentration in patients with severe disease. The sensitivity of PCR from respiratory specimens was 67.6% (95% CI 50.1–85.5). Conclusion: In this cohort, we did not find an association between pharmacologic immunosuppression and disease severity. Lymphopenia at diagnosis was an independent risk factor for mortality. This simple marker may aid clinicians in determining disease prognosis.

Blastomycosis in Minnesota, USA, 1999-2018

Blastomycosis is a systemic disease caused by Blastomyces spp. fungi. To determine its epidemiology in blastomycosis-endemic Minnesota, USA, we evaluated all cases reported to public health officials during 1999-2018. We focused on time to diagnosis, exposure activities, and exposure location. A total of 671 cases and a median of 34 cases/year were reported. Median time to diagnosis was 31 days; 61% of patients were not tested for blastomycosis until they were hospitalized. The case-fatality rate was 10%, and patients who died were 5.3 times more likely to have a concurrent medical condition. Outdoor activities and soil exposure were reported by many patients, but no specific activity or exposure was common to most. Almost one third of patients were probably exposed in geographic areas other than their home county. Providers should consider alternative etiologies for patients with pneumonia not responding to antibacterial treatment, and public health officials should increase awareness in blastomycosis-endemic areas.

Smoking as a Risk Factor of Invasive Fungal Disease: Systematic Review and Meta-Analysis

To investigate the association between smoking and invasive fungal disease (IFD), we searched MEDLINE and Web of Science for studies published until September 2018. Two authors independently performed study selection and data extraction. Relative risks (RRs) were pooled using random-effects meta-analysis. We included 25 studies (18 171 participants; 2527 IFD cases). The meta-analysis showed an increased risk of IFD in smokers (RR 1.41 [95% confidence interval 1.09-1.81]; P = .008). The risk of IFD was higher in retrospective than in prospective studies (RR 1.93 [1.28-2.92] vs. 1.02 [0.78-1.34]; P = .04), in studies with multivariate adjustment compared to studies with univariate analysis (RR 2.15 [1.27-3.64] vs. 1.15 [0.88-1.51]; P = .06), and in studies published after 2002 (RR 2.08 [1.37-3.15] vs. 0.95 [0.75-1.22]; P = .008); other subgroup characteristics did not significantly influence the association in metaregression. Smoking cessation strategies should be implemented, especially in patients who are already at risk for IFD.

Blastomycosis with rapid-onset acute respiratory distress syndrome in an urban setting

While blastomycosis is endemic to eastern USA and northwestern Ontario, acquisition is an anomaly in urban settings. We present a 54-year-old immunocompetent man from the greater Toronto area with no travel, who presented with a 3-week history of chest pain and dyspnoea. Initial radiographic workup revealed a mass-like opacification in the right apical mediastinum. Extensive investigations including bronchoscopy with bronchoalveolar lavage, mediastinal mass biopsy with fungal and mycobacterial cultures and multiple stains, and CT were unrevealing. The patient progressed to respiratory failure over 4 months. Ultimately, sputum and bone marrow cultures confirmed a diagnosis of disseminated blastomycosis. The patient required prolonged extracorporeal membrane oxygenation and ongoing ventilation postdecannulation. Our case highlights diagnostic challenges with blastomycosis, particularly in immunocompetent individuals with no travel to recreational areas, and emphasises the importance of maintaining a high index of suspicion and sending fungal cultures of appropriate specimens and/or cytopathology in clinically compatible cases.

Mortality associated with Blastomyces dermatitidis infection: A systematic review of the literature and meta-analysis

Published case fatality in blastomycosis patients ranges between 4% and 78%. This study aimed to assess mortality associated with blastomycosis and identify its associated risk factors. We conducted a systematic review of publications related to Blastomyces dermatitidis available in PubMed and Scopus databases. Studies that reported data on blastomycosis mortality and that were published from inception through February 2018 were assessed and included in the analysis. Using the R meta package, a random-effect model meta-analysis was used to calculate pooled and stratified estimates of case-fatality proportions and risk ratios. Of 1553 publications, we included 20 studies reporting on a total of 2820 cases of blastomycosis between 1970 and 2014 and three case series reports with 10, 21, and 36 patients. The mean or median ages ranged from 28 to 59 years. Mortality was defined as attributable mortality caused by blastomycosis in 13 studies. Among 14 studies with a standard error ≤0.05, the overall pooled mortality was 6.6% (95% confidence interval [CI], 4.9-8.2) with 57% heterogeneity. The mortality rate was 37% (95% CI, 23-51) in immunocompromised patients and 75% (95% CI, 53-96) in patients who developed an acute respiratory distress syndrome (ARDS) (n = 3 studies each). ARDS was the only identified risk factor in general patients (risk ratio = 10.2). The overall mortality was significantly higher in studies involving immunocompromised patients and ARDS patients. Our analysis showed considerable heterogeneity among studies. Inconsistent mortality definitions may have contributed to the observed heterogeneity. Further research is needed to assess potential risk factors for mortality.

Emerging Fungal Infections: New Patients, New Patterns, and New Pathogens

The landscape of clinical mycology is constantly changing. New therapies for malignant and autoimmune diseases have led to new risk factors for unusual mycoses. Invasive candidiasis is increasingly caused by non-albicans Candida spp., including C. auris, a multidrug-resistant yeast with the potential for nosocomial transmission that has rapidly spread globally. The use of mould-active antifungal prophylaxis in patients with cancer or transplantation has decreased the incidence of invasive fungal disease, but shifted the balance of mould disease in these patients to those from non-fumigatus Aspergillus species, Mucorales, and Scedosporium/Lomentospora spp. The agricultural application of triazole pesticides has driven an emergence of azole-resistant A. fumigatus in environmental and clinical isolates. The widespread use of topical antifungals with corticosteroids in India has resulted in Trichophyton mentagrophytes causing recalcitrant dermatophytosis. New dimorphic fungal pathogens have emerged, including Emergomyces, which cause disseminated mycoses globally, primarily in HIV infected patients, and Blastomyceshelicus and B. percursus, causes of atypical blastomycosis in western parts of North America and in Africa, respectively. In North America, regions of geographic risk for coccidioidomycosis, histoplasmosis, and blastomycosis have expanded, possibly related to climate change. In Brazil, zoonotic sporotrichosis caused by Sporothrix brasiliensis has emerged as an important disease of felines and people.

Epidemiology and Geographic Distribution of Blastomycosis, Histoplasmosis, and Coccidioidomycosis, Ontario, Canada, 1990-2015

Elevated incidence of blastomycosis in Ontario calls for diagnostic vigilance.

Endemic mycoses represent a growing public health challenge in North America. We describe the epidemiology of 1,392 microbiology laboratory–confirmed cases of blastomycosis, histoplasmosis, and coccidioidomycosis in Ontario during 1990–2015. Blastomycosis was the most common infection (1,092 cases; incidence of 0.41 cases/100,000 population), followed by histoplasmosis (211 cases) and coccidioidomycosis (89 cases). Incidence of blastomycosis increased from 1995 to 2001 and has remained elevated, especially in the northwest region, incorporating several localized hotspots where disease incidence (10.9 cases/100,000 population) is 12.6 times greater than in any other region of the province. This retrospective study substantially increases the number of known endemic fungal infections reported in Canada, confirms Ontario as an important region of endemicity for blastomycosis and histoplasmosis, and provides an epidemiologic baseline for future disease surveillance. Clinicians should include blastomycosis and histoplasmosis in the differential diagnosis of antibiotic-refractory pneumonia in patients traveling to or residing in Ontario.

Blastomycosis hospitalizations in northwestern Ontario: 2006-2015

BACKGROUND

Blastomycosis, caused by the organism Blastomyces dermatitidis, is an invasive fungal disease found in Central Canada and Central and Midwestern United States.

OBJECTIVE

To describe trends in and epidemiology of hospitalized cases of blastomycosis cases reported among northwestern Ontario residents between 2006 and 2015.

METHODS

Blastomycosis hospitalization data were extracted from the Discharge Abstract Database (DAD), accessed through IntelliHEALTH Ontario. The DAD includes administrative, clinical and demographic information on hospital discharges provided by the Canadian Institute for Health Information (CIHI). Blastomycosis records were identified using ICD-10 codes B40.0 to B40.9. Hospitalization rates were calculated for all of Ontario, and age-specific hospitalization rates were calculated for northwestern Ontario and analyzed by local health region, time and seasonality as well as presenting symptoms.

RESULTS

There were 581 hospitalizations for blastomycosis reported in Ontario over this 10-year period. Of these, 245 (42%) were from northwestern Ontario, although this region accounts for only 0.6% of the Ontario population. The average hospitalization rate for blastomycosis in northwestern Ontario was 35.0 per 100,000 per year. This rate varied from 1.7 in the Red Lake region to 57.9 in the Kenora region. The most common presentation was acute pulmonary symptoms. Men were 1.36 times more likely to be hospitalized for blastomycosis than were women (95% confidence interval [CI]: 1.06-1.75, P<0.05). Most hospitalizations were registered in the late fall months, suggesting blastomycosis exposure in the spring/summer season followed by a lengthy incubation period.

CONCLUSION

Areas of northwestern Ontario have high reported rates of blastomycosis. It is not known to what extent there are regional differences in other states and provinces. Interregional differences may warrant prioritizing strategies for blastomycosis prevention and control as well as additional research and surveillance.

Serious fungal infections in Canada

There are currently no nationwide epidemiological data on fungal infections in Canada. We estimated the burden of serious fungal diseases using literature review and modeling, as per a methodology previously described by the LIFE program ( http://www.LIFE-worldwide.org ). Among the population of Canada (35.5 million in 2014), it was estimated that approximately 1.8% are affected by a serious fungal infection. Recurrent vulvovaginal candidiasis, severe asthma with fungal sensitization, and allergic bronchopulmonary aspergillosis are the most frequent infections, with population prevalences of 498,688 (1403/100,000), 73,344 (206/100,000), and 61,854 (174/100,000) cases, respectively. Over 3000 invasive fungal infections are estimated to occur annually, with incidences of 2068 cases (5.8/100,000) of invasive candidiasis, 566 cases (1.6/100,000) of invasive aspergillosis, 252 cases (0.71/100,000) of Pneumocystis pneumonia, 99 cases (0.28/100,000) of endemic mycoses, and 63 cases (0.18/100,000) of cryptococcosis. These estimates warrant validation through more formal epidemiological studies in Canada.

Red Fox as Sentinel for Blastomyces dermatitidis, Ontario, Canada

Blastomyces dermatitidis, a fungus that can cause fatal infection in humans and other mammals, is not readily recoverable from soil, its environmental reservoir. Because of the red fox’s widespread distribution, susceptibility to B. dermatitidis, close association with soil, and well-defined home ranges, this animal has potential utility as a sentinel for this fungus.

Management and Outcomes of Acute Respiratory Distress Syndrome Caused by Blastomycosis: A Retrospective Case Series

Acute respiratory distress syndrome (ARDS) is an uncommon, highly fatal, and poorly understood manifestation of blastomycosis. Optimal management remains unknown, including the roles of adjunctive corticosteroids and extracorporeal membrane oxygenation (ECMO).We conducted a retrospective chart review of patients with ARDS caused by blastomycosis, managed in intensive care units in Manitoba, Canada, from 1992 to 2014. ARDS was defined using the Berlin definition. Corticosteroid therapy was defined as ≥150 mg cortisol equivalent in 24 hours. Logistic regression was used to identify determinants of a fatal outcome, and bootstrap resampling was used to assess sample size requirements.Forty-three patients with ARDS caused by blastomycosis were identified. ARDS was mild, moderate, and severe in 2 (5%), 12 (28%), and 29 (67%) patients, respectively. Management included amphotericin B (n = 42, 98%), vasopressors (n = 36, 84%), corticosteroids (n = 22, 51%), renal replacement (n = 13, 30%), and ECMO (n = 4, 11%). Seventeen patients (40%) died. All patients treated with ECMO survived (P = 0.14). Corticosteroids were not associated with survival benefit in univariate (P = 0.43) or multivariate analyses (odds ratio 0.52, 95% confidence interval 0.11-2.34). Bootstrap studies indicated that almost 500 patients would be needed to confirm a significant reduction in mortality from corticosteroids (type I error = 0.05, power = 80%).Blastomycosis is an uncommon, albeit important, cause of ARDS in this geographic area. Given the rarity of disease and the large cohort needed to demonstrate mortality benefit, the role of adjunctive therapies, including corticosteroids and ECMO, may remain unconfirmed, and clinical judgment should guide management decisions.