Can a Borrelia infection cause ALS?

The possibility that ALS is caused by a Borrelia infection has been suspected and debated since the 1980s (when Borrelia was first described). To date, a link between Borrelia infection and ALS has not been established. Borrelia infection primarily affects the skin and joints; in rare cases, it can also affect the nervous system (neuroborreliosis). In this scenario, patients experience pain, sensory disturbances, and paresis of nerves and nerve roots. Cerebrospinal fluid analysis reveals signs of inflammation, indicating that the immune system is fighting off the Borrelia pathogens. The clinical picture of ALS differs from the typical symptoms of neuroborreliosis (in ALS, there are no sensory disturbances and no involvement of the skin or joints).

Cerebrospinal fluid analysis in ALS also shows no signs of inflammation. Given the different physical symptoms and the results of cerebrospinal fluid analysis, distinguishing between the two conditions is usually straightforward. In very rare cases, however, it can be difficult to differentiate between them. In such cases, antibiotic therapy—which is highly effective against neuroborreliosis—is warranted.