Sera from 305 dogs were analyzed by enzyme-linked immunosorbent assay (ELIS
A) to determine presence of the antibody anti-gp43, which reacts to a speci
fic antigen of Paracoccidioides brasiliensis. The dogs were divided into th
ree groups according to their origin: urban dogs (animals with little or no
contact with rural areas); suburban dogs (from the urban outskirts); and r
ural dogs. There was a significant difference between groups (P <0.05). Rur
al dogs reacted positively in 89.5% of cases, followed by suburban (48.8%)
and urban dogs (14.8%). There were no differences between male and female d
ogs. In an attempt to verify the feasibility of skin testing with gp43 to d
etermine sensitization against P. brasiliensis in dogs, suburban (n = 61) a
nd rural (n = 21) dogs were tested, showing positivity of 13.1 and 38.1%, r
espectively, Six dogs that had higher ELISA titers and also showed strong r
eactions in skin testing were killed in an attempt to isolate P, brasiliens
is. The fungus was not detected by culture or histopathological analysis in
these dogs, suggesting that dogs have a natural resistance or that they en
counter an inoculum level that is insufficient to cause disease. These resu
lts indicate that ELISA and skin testing can be useful in the epidemiologic
al study of paracoccidioidomycosis in dogs and that encounter with the fung
us in nature is a frequent event.