Canary finches (Serinus canaria) as an avian infection model for Lyme borreliosis.

To investigate if passerine birds can be used as an avian model for Lyme borreliosis, the Borrelia burgdorferi sensu stricto strain Sh2-82 was inoculated subcutaneously on Canary finches (Serinus canaria). Spirochaetes could be detected in the blood by direct microscopy and an immunofluorescence assay (IFA) up to 2 weeks after the inoculation. DNA amplification (PCR) revealed B. burgdorferi DNA in the serum for up to 3 weeks, in the faeces up to 4 weeks, and from several internal organs at autopsy 3 months after the inoculation. Of particular interest was the finding of B. burgdorferi DNA in the liver of all birds at the end of the experiment, indicating a persistent infection. Four weeks after the primary infection, all infected birds showed an increase in anti Borrelia IgG antibodies and after 6 weeks all birds had seroconverted. Except for a brief episode of diarrhoea, none of the birds showed any signs of disease. This study shows that passerine birds experience short-term spirochaetemia after infection with B. burgdorferi, but show few clinical symptoms. This suggests that, although these birds can act as reservoirs of B. burgdorferi s.s., they may be of less importance as long lasting amplifiers for this pathogen.