ABSTRACT
Chapter 5 provides an overview of outbreak detection and investigation. Successful outbreak investigations follow a systematic approach. The importance of preparing for outbreaks is stressed, as is the development of a learning culture whereby lessons learned from an outbreak are implemented and fed into the preparations for future outbreaks. Once an outbreak has been confirmed, it is essential to identify the source of the pathogen and to quickly control its spread to minimize human suffering and negative economic impacts. This requires a coordinated effort by an established, functional multi-disciplinary team of key participants (public health physicians, epidemiologists, clinical and environmental microbiologists, media spokespersons, and in the case of waterborne outbreaks, drinking water purveyors). Epidemiological studies to link illness and exposure route can be simply descriptive (i.e., collection of case information and generation of an epidemic curve) or based on a case-control approach (i.e., comparison of the incidence of illness in exposed and non-exposed populations). There is some concern among epidemiologists that case-control studies may suffer from various biases leading to the misclassification of data and may not possess sufficient statistical power to link illness and exposure source. The presence of acquired immunity within the exposed population can also affect the power of the study.
