Infectious disease surveillance in North Rhine-Westphalia: first steps in the development of an early warning system.

It is often difficult to detect warning signals on infectious disease outbreaks from raw surveillance data. Data need to be used for a timely generation and distribution of information on the current state of infectious diseases. This offers the opportunity to detect outbreaks and to initiate preventive measures. To improve the surveillance system in North Rhine-Westphalia we have introduced an infectious disease barometer, a simple tool based on weekly notification data. The aim of this tool is not to provide in depth data analysis, but to help to detect clusters or outbreaks. This can be the first step in the development of an early warning system and can support epidemiological investigation and policy making.