incident.qmd

<!-- # Event {.unnumbered} -->

An Event in the data model refers to a distinct wildlife health event that occurs at a specific longitude and latitude on a particular date (time stamp). A single Event (point) can include between zero Collections (e.g., opportunistic detection of Sources) up to a indefinite number of Collections.

The definition of a wildlife health event, and thus what an 'Event' represents, will inevitably vary depending on the Surveillance Activity. For example, in active surveillance efforts, an Event can refer to the site where animals are captured, starting at time *t*, to obtain Specimens, the site and time where a dead dead animal is found during a ranger patrol, the site and time where water is collected from a pond. In the case of surveillance for vector-borne diseases, an Event can represent a site where one or several traps for vectors are deployed at time X. In the case of beached fish, an Event can represent the position and time of recording of each individual dead fish in one extreme, or the total count of dead fish across the beach reported as a single point in the other extreme. In the context of a wet market, the definition of Event can be applied to the market, to vendors, to the stalls of vendors, or to the cages in the stalls at time *t*. For study A the Event could the grid cell where traps are deployed, whilst for study B it could each trap within a grid cell. 

Moreover, the presence of at least one Source could be needed to establish an Event. For example, a dead animal found during a ranger patrol at time *t* leads to an Event. In Active Surveillance, an **Event might not have any Source, for example, a capturing effort starting at time *t* that ends with no animals captured**. Additionally, the definition of an Event can include or not healthy animals. In the example of the dead animal found by the ranger at time *t*, it could be possible that the Event definition includes the documentation of healthy animals or not.

Consequently, an Event in wildlife health surveillance can represent different entities depending on the objectives and the methodology used to collect wildlife health data. **It is up to the user to define what unit the Event represents and report it in the Surveillance Activity metadata. It is recommended that each Surveillance Activity has a single definition of what an Event represents**. 

Properties of Event include the Start Date, Event ID, Event Code, Event Cross Reference ID, Event Cross Reference Origin, Longitude, Latitude, the Coordinate Reference System used, among others (see Data Dictionary). If the data of interest per Event includes attributes that are not part of the data model, it has to be reported as part of the Surveillance Activity metadata and it is recommended to keep track of these attributes in a different source (another database, an excel sheet, etc.). Common extra Attributes can be added to the data model in future versions. Missing Options for single- and multi-selection attributes of Events can be added as long as they promote a controlled vocabulary.