One third of all deaths worldwide are due to infection diseases. Even if we think we have found the key to a causative organism, which would enable us to combat it, we would find that the lock has been changed. Streptococci possess a particularly effective lock and key service ­­­-for decades they have evaded our attempts for therapy. The roots for this problem are not found in our part of the world, but in regions outside the middle of Europe, where medical treatment is less coherent. If streptococcal infections are not sufficiently treated, the bacteria settle in the body, causing chronic diseases. Rheumatic heart disease in children is a typical example of such a process.