They are borne by ticks and can cause acute and chronic symptoms in joints, muscles and the nervous system - the bacteria that cause Lyme borreliosis, which 80,000 people in Germany contract every year. Heidelberg researchers have now succeeded in identifying their structure more accurately. Using a cryo-tomography microscope, the previously unknown detailed structure of the spirochete bacteria can be shown in three dimensions. One finding - that borrelia types in North America more often affect the joints and in Europe the skin and nervous system as well - seems to stem from the characteristics of their motility system.