Blastomycosis, 2019

In 2019, 79 blastomycosis cases were reported, the highest number since enhanced surveillance began in 1999, and 21 higher than last year’s previous record. This continues the increase in cases seen in the past few years. The median age of cases was 41.5 years (range, 4 to 76), and 56 (71%) were male. Fifty-six (74%) cases were white, 8 (11%) were Asian/Pacific Islander, 7 (9%) were black, 5 (7%) were American Indian/Alaskan Native, and 3 were of unknown race. Fifty-one (65%) cases were hospitalized for a median of 8 days (range, 1 to 78). Five (6%) cases died, which is a lower fatality rate than the normally observed 9-10%, and improved over 2017-2018 when the case fatality rate was 15%. Blastomycosis was the cause of death for all five. Twenty-two cases (28%) had immunocompromising health conditions or medication use, including 9 (11%) with diabetes, and 1 (1%) on medications for rheumatoid arthritis. Sixty (76%) cases had pulmonary infection, 11 (14%) had disseminated infection, and 8 (10%) had extrapulmonary infection.

One large outbreak occurred in Minnesota residents in 2019; however, the exposure occurred in Wisconsin. Twelve cases all reported tubing, primarily in early August, on a popular Wisconsin river. Eleven cases were part of three different groups. The twelfth case was also part of a group, but no other members developed illness. Half of these outbreak cases were male and half were female, a much different ratio than in sporadic cases. Five (42%) cases were white, 4 (33%) were black, 2 (17%) were Asian/Pacific Islander and 1 (8%) was unknown. The median age was 28 years (range, 21 to 41 years). Eight cases (67%) were hospitalized. From 1999 to 2019, 750 cases were reported; the annual median is 34 cases (range, 22 to 79), but the median for the most recent 5 years is 44 cases/year. In 2019, the incidence statewide was 1.4 cases/100,000 population, compared to the 1999- 2019 median annual incidence of 0.63 cases/100,000. Exposure information is available for 605 cases. The largest number, 131 (22%), were likely exposed in St. Louis County. Seventyfour (12%) cases were likely exposed in Itasca County, 52 (9%) in Cass County, 21 (3%) in Hennepin County, and 17 (3%) in Beltrami County. (Figure 1).

• Find up to date information at>> Blastomycosis (Blastomyces dermatitidis)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2019