About Outbreak


Outbreak simulates disease dynamics under an individually base model of transitions among susceptible, exposed, infectious and recovered individuals. Outbreak provides several options for modes of transmission (random contact within populations, spatially based transmission, contact with environmental sources of disease) and provides options for management through vaccination or culling. The current version 2 of Outbreak was written by Robert Lacy, based on Outbreak version 1 designed by JP Pollak, PS Miller, RC Lacy, L Hungerford, and P Bright.

Outbreak is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.


Outbreak is constantly changing. We fix bugs when they are identified, although not always immediately if the bug is more of a nuisance (e.g., bad formatting on a screen or output file) rather than something that is causing misleading results. We also add new features and options when we believe that they will be useful to a significant number of users, and when we have the time to add the enhancements. We frequently make small changes to screen lay-outs, screen text, and file formats when we feel that the change will improve the program for users. In the Help menu of the program there is an option to check for any updates that are more recent than the version you are currently using.

Note that we do not guarantee that all changes to the program have been documented here. In particular, we don’t list here many very minor changes made to the interface.

We also cannot guarantee that all bugs in code or errors in algorithms have now been fixed. Reports of apparent bugs can be made at scti.tools/help-support/ . We are very grateful to the many colleagues who have carefully documented and reported apparent bugs. Even when the issue turns out to be a misunderstanding by the user, and not a true bug, we still appreciate the report. (Indeed, we are happier when the problem turns out not to be a bug in the program!)

  • 9 May 2020

    A fix was made to the FunctionEvaluator so that it worked when functions contained state variables.

  • 6 February 2020 (version 2.11)

    The output of R0 (infections caused by each infectious individual) is now provided both as a cumulative value (as it was before) and as the value on that given day (the number of infections caused by individuals who exit the Infectious state on that day).

  • 6 January 2020 (version 2.10)

    Some minor fixes and changing website links from vortex10.org (now discontinued) to scti.tools have been consolidated into a new release.

  • 20 May 2019 (version 2.9)

    Any PSvars are now initialized both before and again after the initial population is created. This allows PSvars to be used in setting, for example, initial spatial locations and ISvars, while still allowing the initialization of PSvars to use variables that describe the initial population.

  • 13 October 2018 (version 2.8)

    A menu item was added to allow changing to a different scenario from any input tab, and a dropdown list was added to allow moving between scenarios from the Results window.