An ELISA for the early diagnosis of acute canine babesiosis detecting circulating antigen of large Babesia spp

Abstract: Babesia canis is the predominant Babesia species in dogs in Europe and is responsible for a severe and fatal disease. An increase in global pet tourism and a widening of the geographic distribution of the tick vector has led to the emergence of infections in areas where previously only imported cases have been reported. Due to the potential for rapid and serious disease progression, direct parasite detection by stained blood smears and light microscopy or DNA-based methods have traditionally been used for the diagnosis of acute infections. This study describes the production of a murine monoclonal antibody (‘mAb BcFIII 7/1/2’) that reacts to a 65 kDa corpuscular epitope present in B. canis-infected erythrocytes and can be used in an ELISA to detect circulating Babesia antigen during acute infections. The sensitivity of the ELISA was 100% (95%CI: 84.5–100) as determined using blood lysate samples from 27 dogs with acute B. canis infections. Sensitivity was reduced to 53.8% in 13 patent Babesia vogeli infections (95%CI: 26.1–79.6) based on the current test design using convalescent serum from a B. canis-infected dog. The specificity was determined to be 86.4% (95%CI: 64–96.4) using 22 samples from healthy canine blood donors. In the course of acute B. canis infections, the ELISA showed a positive result at the same time as a positive PCR result was recorded. This was 24 to 48 hours before parasites could be detected by light microscopy. Convalescent samples collected from 6 B. canis-infected dogs at least 14 days post treatment resulted in negative ELISA reactions.

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