Lyme disease is caused by bacteria (spirochetes), which usually enter the body through a tick bite. Usually the infection proceeds without complications and can be eliminated or controlled by the normal immune system. However, if the immune defence is insufficient, the infection may cause chronic symptoms (e.g. in the joints). A vaccination against Lyme disease is not yet available. For this reason, appropriate diagnostics should be considered in the case of tick contact and corresponding symptoms.
As well as Lyme disease, additional pathogens (e.g. rickettsia, babesia and ehrlichia) can also be transmitted by a tick bite. The most important pathogens of Lyme disease, Borrelia burgdorferi, Borrelia garinii and Borrelia afzelii are related to the syphilis pathogen Treponema pallidum.