Borrelia are bacterial pathogens that infect the cell interior. All organ systems can be affected (multisystem disease). However, Lyme disease rarely occurs alone: other pathogens (co-infections) and additional stresses (e.g. with heavy metals) are frequent accompanying factors. The symptoms are correspondingly varied. The number and severity of symptoms vary greatly from person to person. In the course of time, the symptoms change when the inflammations, immune phenomena and secondary disorders caused by the pathogens develop a potentiating momentum of their own. Often, it is no longer possible to distinguish between directly pathogen-related symptoms and indirect secondary symptoms.

Many people go through a true odyssey until they are finally diagnosed with chronic Lyme disease. This is due to the fact that there is no single test that by itself reliably proves or excludes such a disease. Only the combination of different tests allows a statement whether the presence of chronic Lyme disease is probable, possible or unlikely.