The questionnaire was designed for online completion to expedite data gathering whilst the EI outbreak was occurring. Questionnaire content was reviewed by subject matter experts, including a small group of public health professionals in NSW Health, some of whom had been involved in aiding the NSW DPI in disease control management, a NSW DPI Local District Control Centre Controller who was responsible for leading control activities, and representatives of the Australian Horse Industry Council (AHIC). Ethics approval for the study was obtained through the University of Western Sydney ethics committee.