As September 5, 2011, 24 people have participated in the survey, with 14 completing all the questions. Although providing personal information was optional, half the respondents supplied biographical details. Most of the respondents were based in North America, typically from state or county public health departments, although three were based outside North America (one from Taiwan and two from the UK NHS). Apart from one assistant professor, all the respondents had either 'public health', 'epidemiologist' or 'syndromic surveillance' in their job titles. Strong disagreement was expressed by a minority of respondents on 7 of the 279 ESSO concepts (see Table 1 ). Only 2 concepts*'hoarseness' (respiratory syndrome) and 'concussion' (neurological syndrome)*elicited disagreement (or strong disagreement) with ESSO syndrome definitions among a majority of respondents. We are currently developing a strategy to 'flag' concepts with high levels of disagreement in order to better inform ESSO users.