Abstract
In Portugal canine brucellosis due to Brucella canis has historically not been regarded as endemic, but little is known about the real epidemiologic situation. Laboratory testing is only done in animals traveling from Portugal to endemic areas, or after veterinarian request following clinical symptoms. Serological positive reactions are rarely reported, and B. canis has never been isolated in Portugal. As it is not considered a notifiable disease, no official prevalence data are available, representing a challenge for studying its epidemiology. The purpose of this retrospective study was to get insights into the occurrence of B. canis in dogs in Portugal. We screened a collection of serum samples received between 2014 and 2021 at the National animal health reference laboratory (INIAV) for serological control. The collection includes 642 samples from different regions in Portugal, including Azores and Madeira. All samples were tested by complement fixationtest (based on B. ovis antigen, CFT-B. ovis); from these, 438 samples were also tested by rapid slide agglutination test (RSAT and ME-RSAT) and/or immunochromatographic test (ICT). In addition, 252 samples from dogs showing clinical symptoms (including blood samples, vaginal swabs, aborted fetus) were submitted for detection of Brucella spp. with polymerase chain reaction (PCR). There was no positive serology for smooth Brucella spp. The frequency of positive serologic results was 9,7% (62 in 642 dogs) using CFT-B. ovis, but 7,3% of the tested samples showed anti-complementary reaction. From the 62 positive dogs, 21 tested positive in RSAT, ME-RSAT and/or ICT. Regarding the samples submitted to PCR, 19% (48/252) resulted positive. Although the results obtained belong to pre-selected samples (not reflecting the national occurrence) collected from a heterogeneous group of dogs, this first preliminary results suggest a low seroprevalence of B. canis infection in Portugal. The study still ongoing in order to increase the number of samples, the geographic coverage and the evaluation of breeding kennels across Portugal.
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