Exploring Options for Syndromic Surveillance in Aquaculture: Outbreak Detection of Salmon Pancreas Disease Using Production Data from Norwegian Farms

Figure 3

Schematic representation of production months and fish cohorts considered positive or negative for pancreas disease (PD) using the proposed syndromic surveillance system for outbreak alarms. In this example, an outbreak alarm requires three consecutive months with aberration signals. Each rectangle represents one production month, and the sequential rectangles represent farms with fish cohorts A–F. Cohort A had fish stocked for less than 3 months and was ineligible for outbreak generation, represented by dark gray rectangles. Cohort B, shown with all empty rectangles, did not exhibit any aberration signals or trigger outbreak alarms. Cohorts C and D had aberration signals, represented by exclamation marks, but they did not meet the criteria for outbreak alarms. Conversely, Cohorts E and F had PD outbreak alarms, represented by light gray rectangles after three consecutive months with aberration signals. Cohort E and F were positive for PD during five and one production months, respectively, as indicated by the number of light gray rectangles representing the alarms. In summary, Cohorts B, C, and D had no alarms for PD outbreaks in any of the production months and were therefore classified as negative PD cohorts. On the other hand, Cohorts E and F had monthly alarms for PD outbreaks and were classified as positive PD cohorts.