Excellent Example of One Health in Action – Human, Animal, Environment considerations. Cluster of Blastomycosis in humans and dogs in Wisconsin

Blastomycosis, caused by the fungus Blastomyces, is a rare but potentially serious infection in humans and animals. It is endemic in Wisconsin where this report originates. This narrative describes how a local veterinarian alerted the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) and the Wisconsin Department of Health Services (DHS) of a cluster of four dogs with diagnoses of blastomycosis, all living within a 1-mile area that is not usually considered an area with hyperendemic transmission. Review of surveillance data identified two human cases reported in the same area within 3 weeks of the canine cases.  

Though blastomycosis is reportable in humans in Wisconsin, it is not reportable in animals. Fortunately, in this case alerts were issued to physicians and veterinarians in the surrounding counties, emphasizing the importance of timely diagnosis and treatment of blastomycosis. This alert encouraged local veterinarians to report cases potentially associated with this cluster. As a result, multiple human cases were diagnosed after notification of the ongoing cluster.

Environmental assessments identified a river and unpaved paths running through the neighborhoods under investigation. Construction in this neighborhood during the past decade might have dispersed Blastomyces spores. A more comprehensive investigation was launched to characterize potential environmental exposure sources in this community. Analysis of these data is ongoing.

Segaloff HE, Wu K, Shaw S, et al. Notes from the Field: Cluster of Blastomycosis Among Neighborhood Residents — St. Croix County, Wisconsin, 2022. MMWR Morb Mortal Wkly Rep 2023;72:348–349. DOI: http://dx.doi.org/10.15585/mmwr.mm7213a5.