Here is evidence of past infection of dogs with B burgdorferi sensu lato from Polish Research. One area 1.7% ( 7 in 408 cases ). Identified as B afzelii. The second area showed a 16.3% infection rate to B burgdorferi sensu stricto. Both these occur in the Highlands to my knowledge. B garinii occurs around the Bath area. The New Forest has B burgdorferi. Consequently if you pick up the infection in one area and live elsewhere they don't test you for the right strain as they follow the HPA guidelines. Less said about that and the GPs.
The authors of the paper stress the fact the infection can be transferred to humans. It would therefore be sensible to keep your dogs' tick treatment up to date both from their and your own health.

sensu lato: in the widest sense , sensu stricto: in the narrowest sense Have to use these terms as very complex organism which changes its surface coat at different stages in the cycle of infecting ticks and other animals. Actually deer don't carry the infection just act as a blood meal for the ticks. So if the ticks are infected before feeding on the deer don't transmit the disease to the deer but it stays in them.