Do CuSums have a role in routine communicable disease surveillance?

The swift identification of outbreaks of infection is essential for effective control in the population. One of the functions of surveillance is to detect outbreaks but it could be argued that this is one of the weaker aspects of routine surveillance at present. This paper describes a technique which might meet this surveillance need. The CuSum technique allows rapid measurement of change from expected values based on historical data. It is very simple and seems to be a highly sensitive technique which can signal the need for further scrutiny of the data and/or for public health action, long before a change in incidence is apparent from raw data. This is particularly true for low-incidence infections where large functions can make interpretation difficult. CuSums represent a potentially useful adjunct to other surveillance methods in infection control.