OspA is produced specifically by Borrelia burgdorferi, a bacteria that causes Lyme disease.

BBC: Test for tick disease

The occurrence of Toxoplasma gondii and Borrelia burgdorferi sensu lato in Ixodes ricinus ticks from eastern Poland with the use of PCR.

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And arthritis of a somewhat different sort sometimes follows Lyme disease, an infection caused by Borrelia burgdorferi which is passed on by tick bites.

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However, he said the majority of cases of Lyme disease in the UK were not caused by Borrelia burgdorferi, but by a separate species Borrelia garinii.

BBC: Test for tick disease