Blended Human and Animal Blastomycosis Surveillance System in Minnesota

Background: Blastomycosis is caused by the fungus Blastomyces dermatitidis, found in moist soils along waterways in the Midwest. Transmission of blastomycosis occurs by inhalation of the spores, and the disease generally manifests as acute pulmonary disease. Human cases are reportable to the Minnesota Department of Health (MDH), and veterinary cases are reportable to the Minnesota Board of Animal Health (BAH). Canine cases are more numerous than human cases, and interviewing the owners of infected pets helps define and map blastomycosis-endemic areas. Methods: MDH receives case reports from health care providers (HCPs), infection preventionists (IPs), laboratories, and veterinarians in multiple formats. MDH staff contact HCPs and veterinarians to obtain clinical and demographic data before interviewing case-patients or pet owners for symptom and exposure histories. Case data is entered into an Access database and analyzed using SAS version 9.4. Surveillance data for both human and veterinary cases are posted on the MDH website. Results: Between 1999 and 2014, there were a total of 511 human cases (range, 22-49 cases per year) and 1,146 veterinary cases (range, 52-99 cases) in Minnesota. Both human and veterinary cases were diagnosed year-round. Conclusions: Surveillance of both veterinary and human blastomycosis cases has compelling advantages. Blastomycosis-endemic regions may be more accurately mapped; geographic and temporal clusters of canine cases may be sentinels for human disease risk.