The NAADSM model specification

The NAADSM model specification is intended to be a plain-language description of the conceptual model implemented in NAADSM. Its purposes are to facilitate agreement among current team members on details of the model, to provide a basis for functional testing, and to provide future team members and other users with a complete but accessible description of the model.

For historical reasons, NAADSM version numbers start at 3.0.0. This scheme reflects continuity with SpreadModel1, the conceptual model on which NAADSM was originally based. Version numbers for the NAADSM specification document start at 1.0.0: the first version of the NAADSM specification document was written for NAADSM 3.0.0. For a more thorough description of NAADSM version numbers, please see NAADSM versioning.

Development of NAADSM is on-going, and new versions of the program are written to conform to updated versions of the model specification. The model specification is updated via Requests for Comment (RFCs). RFCs provide detailed descriptions of proposed changes to the model specification. RFCs should include justification for the proposed changes and any supporting documents, e.g., manuscripts from the scientific literature. Changes proposed in RFCs are discussed and may be revised by the NAADSM Development Team. An RFC that is accepted after evaluation is merged into a new version of the model specification.

The following tables show the relationships between versions of the NAADSM application and the model specification, and list RFCs that have been incorporated in the specification document.


1Schoenbaum, M.A., and Disney, W.T. 2003. Modeling alternative mitigation strategies for a hypothetical outbreak of foot-and-mouth disease in the United States. Prev. Vet. Med. 58: 25-52.

Specification 2.0 (for NAADSM 4.0)

NAADSM 4.0 is the first new major release of NAADSM since its introduction in 2006. This version addresses several deficiences identified in previous versions. Among the most notable differences between NAADSM 4.0 and NAADSM 3.x are the following:

  • Local-area spread is implemented as a mechanism of disease transmission separate from long-distance airborne spread
  • The formulas used for local-area and airborne spread have been fully revised, so that these parameters are more epidemiologically and mathematically plausible
  • A more refined approach to simulating the effect of within-unit prevalence of disease on transmission by direct, local-area, and airborne spread is implemented
Unlike previous releases, NAADSM 4.0 is not fully backward compatible with previous versions. Scenarios developed for NAADSM 3.x must be adapted to run with NAADSM 4.0.

Specification version 2.0 NAADSM version 4.0
  Latest revision:
Adobe PDF document Version 2.0.0
(1 Oct 2012)
  Latest release:
Installer icon NAADSM 4.0.13
(2 July 2013)
  Specification revision history [Show/Hide]
Adobe PDF document Version 2.0.0 (1 Oct 2012) [RFCs adopted]
  Adobe PDF document RFC-20060703ARa Incorporation of a "Dead from disease" state: This RFC introduces a state for units that die out as a result of disease, as might be the case with highly pathogenic strains of avian influenza.
  Adobe PDF document 20070313SD Replacing the algorithm for airborne spread: This RFC proposes the separation of local-area from airborne spread, and alters the formula used to calculate the probabilities of disease transmission by these two mechanisms.
  Adobe PDF document RFC-20090428AR Within-unit prevalence and disease spread by direct contact or local-area spread: This RFC introduces new parameters to more appropriately model the spread of disese by direct contact, local-area spread, and airborne transmission when the option to specify within-unit prevalence is used.
  Adobe PDF document RFC-20090429AR Elimination of delay parameters: This RFC proposes the elimination of rarely used and problematic parameters for delay in the effect of disease exposure by direct contact, indirect contact, and airborne/local-area spread.
  Adobe PDF document RFC-20091016ARa Vaccination queues: This RFC describes a change in the behavior of the model to prevent units that require vaccination from being listed and counted in the vaccination queue multiple times.

Specification 1.2 (for NAADSM 3.2)

This version of NAADSM will allow tracing back from detected units. NAADSM 3.2 will be backward compatible with previous versions: scenarios developed for NAADSM 3.0 or 3.1 will run in NAADSM 3.2 without modification.

Specification version 1.2 NAADSM version 3.2
  Latest revision:
Adobe PDF document Version 1.2.1
(25 Oct 2010)
  Latest release:
Installer icon NAADSM 3.2.19
(2 July 2013)
  Older application releases for this specification [Show/Hide]
 
3.2.12, 3.2.13, 3.2.14, 3.2.15, 3.2.16, 3.2.17
  Specification revision history [Show/Hide]
Adobe PDF document Version 1.2.1 (25 Oct 2010) [RFCs adopted]
  Adobe PDF document RFC-20100907KF Detection: This RFC clarifies the language used to describe detection parameters.
  Adobe PDF document RFC-20091110AR Tracing to previously detected units: This RFC clarifies that the identification by tracing of a unit that has already been detected as diseased will have no effect.
  Adobe PDF document RFC-20091028NH No zero-size units: This RFC clarifies that units cannot be of zero size.
  Adobe PDF document RFC-20070910NH Conflict resolution rewording: This RFC proposes a re-write of the section regarding how potential conflicts and ambiguities in the model are resolved. These changes are proposed for NAADSM 3.2.
  Adobe PDF document RFC-20070514NH New distance formula: This RFC proposes a change to the way distances are calculated in NAADSM. A cartographic projection is applied to to latitude/longitude data to simply the calculation of distances between units. These changes are proposed for NAADSM 3.2.
Adobe PDF document Version 1.2.0 (11 Jun 2009) [RFCs adopted]
  Adobe PDF document RFC-20090429ARb Vaccination of detected, infected units:This RFC proposes a change to the way detected infected units are currently handled when vaccination is used as a disease control strategy. These changes are proposed for NAADSM 3.2.
  Adobe PDF document RFC-20071127NH Trace in:This RFC proposes a trace-in feature and an ability to do traces that go more than one step. Trace-in is part of the minimum required response to foot-and-mouth disease in the EU directive on FMD. These changes are proposed for NAADSM 3.2.

Specification 1.1 (for NAADSM 3.1)

This version of NAADSM introduced the option to simulate zones for disease detection and control. NAADSM 3.1 is fully backward compatible with version 3.0: scenarios developed for NAADSM 3.0 will run in NAADSM 3.1 without modification.

Specification version 1.1 NAADSM version 3.1
  Latest revision:
Adobe PDF document Version 1.1.2
(25 Oct 2010)
  Latest release:
Installer icon NAADSM 3.1.29
(1 April 2011)
  Older application releases for this specification [Show/Hide]
 
3.1.28, 3.1.27, 3.1.26, 3.1.25, 3.1.24, 3.1.23, 3.1.22, 3.1.21, 3.1.20, 3.1.19, 3.1.18, 3.1.17, 3.1.16, 3.1.15
  Specification revision history [Show/Hide]
Adobe PDF document Version 1.1.2 (25 Oct 2010) [RFCs adopted]
  Adobe PDF document RFC-20100907KF Detection:This RFC clarifies the language used to describe detection parameters.
Adobe PDF document Version 1.1.1 (18 Sep 2008) [RFCs adopted]
  Minor clarifications and formatting changes made in preparation for publication on the the NAADSM website, http://www.naadsm.org.
Adobe PDF document Version 1.1.0 (29 May 2007) [RFCs adopted]
  Adobe PDF document RFC-20070426AR Direct costs of surveillance in zones:This RFC describes the parameters and calculations needed to determine the costs associated with surveillance within zones.
  Adobe PDF document RFC-20051111NHb Zones:This RFC proposes adding disease-control zones that modify movement and detection.

Specification 1.0 (for NAADSM 3.0)

NAADSM 3.0 was the first version developed and released by the international NAADSM Development Team. This version of the model is described by version 1.0 of the NAADSM specification as well as in a paper (Harvey et al. 2007) published in the journal Preventive Veterinary Medicine.

Note: The features of NAADSM 3.0 are a subset of those available in NAADSM 3.1. Scenarios developed for NAADSM 3.0 will run in NAADSM 3.1 without modification. Use of NAADSM 3.1 rather than NAADSM 3.0 is highly recommended.

Specification version 1.0 NAADSM version 3.0
  Latest revision:
Adobe PDF document Version 1.0.7
(24 Apr 2007)
  Latest release:
Installer icon NAADSM 3.0.84
(20 Oct 2006)
  Older application releases for this specification [Show/Hide]
 
3.0.83, 3.0.82, 3.0.81, 3.0.80, 3.0.79
  Specification revision history [Show/Hide]
Adobe PDF document Version 1.0.7 (24 Apr 2007) [RFCs adopted]
  Describes the optional use of fixed rates for direct and indirect contact.
Adobe PDF document Version 1.0.6 (6 Apr 2006) [RFCs adopted]
  Adobe PDF document RFC-20060202AR Trace surveillance: The proposed changes document the behavior of the current version of the core model regarding the process of trace surveillance.
  Adobe PDF document RFC-20051222NH Quarantine: This RFC proposes adding notes for clarification to the direct contact section about potential recipients that are quarantined, about distance limits for shipments, and about the conditions under which a shipment can be dropped.
Adobe PDF document Version 1.0.5 (25 Jan 2006) [RFCs adopted]
  Adobe PDF document RFC-20060103AR Quarantine of units awaiting vaccination: This RFC changes behavior of the model so that units awaiting vaccination are not quarantined and may participate in direct contact with other units.
Adobe PDF document Version 1.0.4 (23 Dec 2005) [RFCs adopted]
  Adobe PDF document RFC-20051130NH Detection diagram: This RFC proposes adding a figure to the detection section to clarify the calculations used for the probability of detection.
  Adobe PDF document RFC-20051208NH Destruction parameters for individual production types:This RFC proposes to change the way ring destruction is described in the model description document.
  Adobe PDF document RFC-20051213AR Cost accounting parameters:The proposed change describes the parameters needed to track direct costs associated with a disease outbreak.
Adobe PDF document Version 1.0.3 (2 Nov 2006) [RFCs adopted]
  Adobe PDF document RFC-20050922ARa Clarification of language regarding destruction of traces: This RFC clarifies the description of destruction of units identified by tracing activities.
  Adobe PDF document RFC-20050922ARb Change in destruction and vaccination priority: This RFC proposes that destruction always take precedence over vaccination when both actions are scheduled to occur on the same simulation day.
  Adobe PDF document RFC-20050922ARc Initiation of a vaccination program: This RFC clarifies the events that must occur before any units are marked for vaccination.
  Adobe PDF document RFC-20050927ARa Clarification of infection timing: The proposed change explicitly codifies the current behavior of the model regarding the timing of infection events.
  Adobe PDF document RFC-20050927ARb Clarification of infection timing: The proposed change explicitly codifies the current behavior of the model regarding the timing of detection events.
  Adobe PDF document RFC-20050928AR Vaccination parameters for individual production types: This RFC describes the approach to vaccination used in legacy versions of SpreadModel, and proposes that it should be implemented in the current version of the model.
Adobe PDF document Version 1.0.2 (19 Feb 2005) [RFCs adopted]
  Reconciles differences between "SpreadModel" and "SHARCSpread" implementations, as discussed in Guelph, Ontario, Canada, Feb. 14 - 15, 2005.
Adobe PDF document Version 1.0.1 (15 Sep 2004) [RFCs adopted]
  Adobe PDF document RFC-20040915NHa Fix for airborne spread algorithm: This RFC proposes a fix to a formula used for airborne spread.
Adobe PDF document Version 1.0.0 (19 May 2004)