The epidemiology of blastomycosis in dogs: north central Wisconsin, USA.

The epidemiological features of 59 consecutive cases of blastomycosis in domestic dogs, from a single veterinary practice in Eagle River, Wisconsin over a 3-year period, were examined by owner interview. The control sample included: (i) all porcupine quill-injured dogs during this time period (outdoor exposed dogs); and (ii) every sixth dog receiving a rabies vaccination during the second year of study (representative of all dogs in the practice). The estimated mean annual incidence of blastomycosis in dogs in this region was 1420:100,000. Blastomycosis cases were more likely to reside within 400 m of a waterway (95%) than quill-injured dogs (63%, P < 0.001) or vaccinated dogs (74%, P = 0.001). Exposure to an excavation was significantly more likely among blastomycosis cases compared to quill-injured dogs, however, no differences were found for age, sex, hunting, swimming and reported exposure to beavers. The geographical clustering of cases in dogs is similar to that previously reported for humans in this region. A close proximity to waterways and an exposure to excavation are significant risk factors for blastomycosis.