Abstract
Group B streptococcus (Streptococcus agalactiae) is proposed as causative agent for the development of the sporadic form of Alzheimer`s disease. Using a fibrinogen binding protein, aggregates are formed including A-beta. After triggering Alzheimer`s disease by the bacterium, the next down-stream events mainly follow the well known so called A-beta hypothesis. The combination of the two hypotheses is able to explain a number of epidemiological and biochemial aspects of Alzheimer's disease.