Serum and urine Blastomyces antigen concentrations as markers of clinical remission in dogs treated for systemic blastomycosis.
BACKGROUND
Serum and urine Blastomyces antigen concentrations can be used to diagnose blastomycosis in dogs.


OBJECTIVE
Blastomyces antigen concentrations correlate with clinical remission in dogs during antifungal treatment, and detect disease relapse after treatment discontinuation.


METHODS
21 dogs with newly diagnosed blastomycosis monitored until clinical remission (Treatment Phase), and 27 dogs monitored over 1 year from the time of antifungal discontinuation or until clinical relapse (After Treatment Phase).


METHODS
Prospective study. Dogs were monitored monthly during treatment and every 3 months after treatment discontinuation, with a complete history, physical exam, chest radiographs, and ocular exam. Urine and serum Blastomyces antigen concentrations were measured at each visit using a quantitative enzyme immunoassay.


RESULTS
At enrollment in the Treatment Phase, Blastomyces antigen was positive in all 21 urine samples (100% sensitivity; 95% CI 85-100%), and in 18 of 20 serum samples (90% sensitivity; 95% CI 70-97%). At 2-4 months of treatment, urine antigen was more sensitive for clinically detectable disease (82%; CI 60-94%) than serum antigen (18%; CI 6-41%). The sensitivity of the urine test for clinical relapse was 71% (CI 36-92%), with close to 100% specificity (CI 84-100%) during after treatment surveillance in this population.


CONCLUSIONS
Urine Blastomyces antigen testing has high sensitivity for active disease at the time of diagnosis and during treatment, and moderate sensitivity but high specificity for clinical relapse. Urine testing should be useful at the time of diagnosis, when treatment discontinuation is being considered, and anytime there is poor clinical response or suspicion of relapse.
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI.
D S
DS
Foy
L A
LA
Trepanier
E J
EJ
Kirsch
L J
LJ
Wheat
D000818:Animals; D000935:Antifungal Agents / Q000627:therapeutic use; D000946:Antigens, Fungal / Q000097:blood* / Q000652:urine; D001758:Blastomyces / Q000276:immunology*; D001759:Blastomycosis / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D004283:Dog Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D004285:Dogs; D008297:Male; D012008:Recurrence; D012074:Remission Induction
D000935:Antifungal Agents; D000946:Antigens, Fungal
Canine; Monitoring; Systemic fungal infection