It was once believed that infectious diseases were under control in the industrialised part of the world. We are now smarter. Globalisation, as well as changing living conditions and international food production, helped to show new infectious diseases, while old-fashioned diseases once again become relevant. To counter this threat, the monitoring of diseases is necessary. The purpose of this disease monitoring is, inter alia: To detect outbreaks so early that the source of infection can be found and the route of infection is broken. In the lecture I will show examples of the use of mathematical algorithms for "automatic" to find outbreaks, just as the use of statistical methods as a tool for undoing outbreaks is mentioned.