After the bite of an insect infected with Borrelia, the germs first spread through the skin (approx. 72 hours) and then through the bloodstream to other tissues. They may later infect various organs. In some cases, the infection spreads to the nervous system.

Some patients – with or without erythema migrans – experience general symptoms such as fatigue, slight fever, muscle and joint pain, headaches, sweating, conjunctivitis, gastrointestinal complaints and swelling of the lymph nodes in the first few weeks after infection.

The erythema migrans, a reddening of the skin in the shape of a shooting disc with a white circle, usually only occurs after a second contact with the borrelia, so it can also be absent.

It makes sense to send in the removed tick after a tick bite to determine whether Borrelia bacteria can be detected in the biting tool. To be on the safe side, antibiotics should be administered immediately for 21 days. If the tick is germ-free, the antibiotic treatment can be discontinued. If the tick is no longer present or another biting insect has caused erythema migrans, an antibody test must be carried out on the blood.