Incidence of coccidioides infection among dogs residing in a region in which the organism is endemic.
OBJECTIVE
To determine the incidence of Coccidioides infection among dogs residing in a region in which the organism is endemic (Pima and Maricopa counties, Arizona) and estimate the rate of clinical illness.


METHODS
Community-based longitudinal and cross-sectional studies.


METHODS
124 healthy 4- to 6-month-old seronegative puppies (longitudinal study) and 381 4- to 18-month-old dogs with unknown serostatus (cross-sectional study).


METHODS
Dogs in the longitudinal study were tested at 6-month intervals for at least 1 year for anticoccidioidal antibodies. Dogs that became ill were evaluated for coccidioidomycosis. Dogs in the cross-sectional study were tested for anticoccidioidal antibodies once, and clinical abnormalities were recorded.


RESULTS
28 of the 104 (27%) dogs that completed the longitudinal study developed anticoccidioidal antibodies. Thirty-two of the 381 (8%) dogs in the cross-sectional study had anticoccidioidal antibodies. Five seropositive dogs in the longitudinal study and 13 seropositive dogs in the cross-sectional study had clinical signs of disease. The remaining seropositive dogs were otherwise healthy and were classified as subclinically infected. Survival analysis indicated that the cumulative probability of infection by 2 years of age was 28%, and the cumulative probability of clinical infection by 2 years of age was 6%. Titers for clinically and subclinically infected dogs overlapped.


CONCLUSIONS
Results suggested that young dogs living in the study area had a high likelihood of becoming infected with Coccidioides spp, but few developed clinical illness. Serologic testing alone was insufficient for a diagnosis of clinical disease because of the overlap in titers between clinically and subclinically infected dogs.
Shubitz
Lisa E
LE
Department of Veterinary Science and Microbiology, University of Arizona, Tucson, AZ 85721, USA.
Butkiewicz
Christine D
CD
Dial
Sharon M
SM
Lindan
Christina P
CP
D000367:Age Factors; D000818:Animals; D000908:Antibodies, Fungal / Q000097:blood*; D001130:Arizona / Q000453:epidemiology; D003045:Coccidioides / Q000276:immunology*; D003047:Coccidioidomycosis / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D003430:Cross-Sectional Studies; D004283:Dog Diseases / Q000453:epidemiology* / Q000473:pathology; D004285:Dogs; D005260:Female; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D016036:Seroepidemiologic Studies
D000908:Antibodies, Fungal