 chapter summary this chapter introduces healthcare outbreak response and provides an outline of corhas principles practices in its entirety while the primary audience for the corha principles practices consists of public health agency personnel the information presented here can also be useful to healthcare professionals and other partners involved in healthcare outbreak response the field of healthcare epidemiology has expanded tremendously during the last few decades an extensive network of healthcare and public health professionals has begun working collaboratively to decrease healthcare associated infections hais and antimicrobial resistance ar one part of this partnership is rapid and efficient outbreak responses to prevent and halt the transmission of pathogens or spread of disease the term hai ar outbreak includes outbreaks involving infections that meet the definition of an hai as well as infections or colonizations with organisms typically associated with the receipt of healthcare including pathogens demonstrating resistance to antimicrobial treatment ar pathogens the term outbreak response or simply response refers to efforts made to assist with assessment and investigation of specific acute hai ar risks the types of hazards addressed by healthcare outbreak response include overt outbreaks clusters of infections sentinel cases e g an uncommon hai or emerging ar threat or serious breaches in infection control practice please consult chapter 1 for additional information including an expanded table of contents with detailed outlines of the topics covered in each chapter and section 