Introduction to network analysis and its implications for animal disease modelling.

Social networks analysis (SNA) has recently been used in veterinary epidemiology to study livestock movements. A network is obtained by considering livestock holdings as nodes in a network and movements among holdings as links among nodes. Social networks analysis enables the study of the network as a whole, exploring all the relationships among pairs of farms. Highly connected livestock holdings in the network can be identified, which can help surveillance and disease prevention activities. Observed livestock movement networks in various countries have shown an important level of contact heterogeneity and clustering (topological, not necessarily geographical or spatial) and understanding the architecture of these networks has provided a better understanding of how infections may spread. The findings of SNA studies of livestock movement should be used to build and parameterise epidemiological models of infection spread in order to improve the reliability of the outputs from these models.

[1]  B. Martínez-López,et al.  Social network analysis. Review of general concepts and use in preventive veterinary medicine. , 2009, Transboundary and emerging diseases.

[2]  Henrik Stryhn,et al.  Description of empirical movement data from Canadian swine herds with an application to a disease spread simulation model. , 2008, Preventive veterinary medicine.

[3]  A. Hill,et al.  The North American Animal Disease Spread Model: a simulation model to assist decision making in evaluating animal disease incursions. , 2007, Preventive veterinary medicine.

[4]  P. Erdos,et al.  On the evolution of random graphs , 1984 .

[5]  R S Morris,et al.  The potential extent of transmission of foot-and-mouth disease: a study of the movement of animals and materials in Southland, New Zealand. , 1993, New Zealand veterinary journal.

[6]  Albert-László Barabási,et al.  Scale-free networks , 2008, Scholarpedia.

[7]  R L Sanson,et al.  A survey to investigate movements off sheep and cattle farms in New Zealand, with reference to the potential transmission of foot-and-mouth disease , 2005, New Zealand veterinary journal.

[8]  R S Morris,et al.  Social-network analysis of Mycobacterium bovis transmission among captive brushtail possums (Trichosurus vulpecula). , 2003, Preventive veterinary medicine.

[9]  N P French,et al.  Patterns of contact within the New Zealand poultry industry. , 2010, Preventive veterinary medicine.

[10]  S. Rushton,et al.  Where diseases and networks collide: lessons to be learnt from a study of the 2001 foot-and-mouth disease epidemic , 2005, Epidemiology and Infection.

[11]  Duncan J. Watts,et al.  Collective dynamics of ‘small-world’ networks , 1998, Nature.

[12]  Albert,et al.  Emergence of scaling in random networks , 1999, Science.

[13]  Rowland R Kao,et al.  The effect of contact heterogeneity and multiple routes of transmission on final epidemic size. , 2006, Mathematical biosciences.

[14]  W. O. Kermack,et al.  A contribution to the mathematical theory of epidemics , 1927 .

[15]  Alessandro Vespignani,et al.  Epidemic dynamics in finite size scale-free networks. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[16]  Albert-László Barabási,et al.  Statistical mechanics of complex networks , 2001, ArXiv.

[17]  Albert-László Barabási,et al.  Internet: Diameter of the World-Wide Web , 1999, Nature.

[18]  Jennifer E. Dent,et al.  Contact structures in the poultry industry in Great Britain: Exploring transmission routes for a potential avian influenza virus epidemic , 2008, BMC veterinary research.

[19]  Sharon L. Milgram,et al.  The Small World Problem , 1967 .

[20]  Håkan Andersson,et al.  Limit theorems for a random graph epidemic model , 1998 .

[21]  I. Kiss,et al.  The network of sheep movements within Great Britain: network properties and their implications for infectious disease spread , 2006, Journal of The Royal Society Interface.

[22]  L. Amaral,et al.  The web of human sexual contacts , 2001, Nature.

[23]  C Dubé,et al.  Comparing network analysis measures to determine potential epidemic size of highly contagious exotic diseases in fragmented monthly networks of dairy cattle movements in Ontario, Canada. , 2008, Transboundary and emerging diseases.

[24]  César A. Hidalgo,et al.  Scale-free networks , 2008, Scholarpedia.

[25]  I. Kiss,et al.  Infectious disease control using contact tracing in random and scale-free networks , 2006, Journal of The Royal Society Interface.

[26]  Torsten Hägerstrand,et al.  Innovation Diffusion As a Spatial Process , 1967 .

[27]  Rowland R Kao,et al.  Disease dynamics over very different time-scales: foot-and-mouth disease and scrapie on the network of livestock movements in the UK , 2007, Journal of The Royal Society Interface.

[28]  Michael P Ward,et al.  Simulation model of within-herd transmission of bovine tuberculosis in Argentine dairy herds. , 2002, Preventive veterinary medicine.

[29]  C R Webb,et al.  Investigating the potential spread of infectious diseases of sheep via agricultural shows in Great Britain , 2005, Epidemiology and Infection.

[30]  B. Bollobás.  The evolution of random graphs , 1984 .

[31]  Matthias Greiner,et al.  Relationship of trade patterns of the Danish swine industry animal movements network to potential disease spread. , 2007, Preventive veterinary medicine.

[32]  T E Carpenter,et al.  Direct and indirect contact rates among beef, dairy, goat, sheep, and swine herds in three California counties, with reference to control of potential foot-and-mouth disease transmission. , 2001, American journal of veterinary research.

[33]  Michalis Faloutsos,et al.  On power-law relationships of the Internet topology , 1999, SIGCOMM '99.

[34]  Stanley Wasserman,et al.  Social Network Analysis: Methods and Applications , 1994 .

[35]  C. Dubé,et al.  A review of network analysis terminology and its application to foot-and-mouth disease modelling and policy development. , 2009, Transboundary and emerging diseases.

[36]  Roy M. Anderson,et al.  The Population Dynamics of Infectious Diseases: Theory and Applications , 1982, Population and Community Biology.

[37]  M. Newman.  Properties of highly clustered networks. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[38]  M. Everett,et al.  Recent network evolution increases the potential for large epidemics in the British cattle population , 2007, Journal of The Royal Society Interface.

[39]  Nicholas J. Savill,et al.  Sheep Movement Networks and the Transmission of Infectious Diseases , 2010, PloS one.

[40]  John Scott.  What is social network analysis , 2010 .

[41]  R. Anderson.  Populations and Infectious Diseases: Ecology or Epidemiology? , 1991 .

[42]  L. Danon,et al.  Demographic structure and pathogen dynamics on the network of livestock movements in Great Britain , 2006, Proceedings of the Royal Society B: Biological Sciences.

[43]  J. Ord,et al.  Spatial Processes. Models and Applications , 1982 .

[44]  A. Barbour,et al.  Epidemics and random graphs , 1990 .

[45]  S. Redner.  How popular is your paper? An empirical study of the citation distribution , 1998, cond-mat/9804163.

[46]  H. Abbey.  An examination of the Reed-Frost theory of epidemics. , 1952, Human biology.

[47]  Ramon Huerta,et al.  Contact tracing and epidemics control in social networks. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[48]  Vladimir Batagelj,et al.  Exploratory Social Network Analysis with Pajek , 2005 .

[49]  R. Morris,et al.  A description of cattle movements in two departments of Buenos Aires province, Argentina. , 2006, Preventive veterinary medicine.

[50]  R. Christley,et al.  Exploring the role of auction markets in cattle movements within Great Britain. , 2007, Preventive veterinary medicine.

[51]  Mark D. F. Shirley,et al.  The impacts of network topology on disease spread , 2005 .

[52]  R. Christley,et al.  Infection in social networks: using network analysis to identify high-risk individuals. , 2005, American journal of epidemiology.

[53]  R. Sanson.  THE DEVELOPMENT OF A DECISION SUPPORT SYSTEM FOR AN ANIMAL DISEASE EMERGENCY , 1993 .

[54]  D. Pfeiffer,et al.  Use of social network analysis to characterize the pattern of animal movements in the initial phases of the 2001 foot and mouth disease (FMD) epidemic in the UK. , 2006, Preventive veterinary medicine.

[55]  R. Christley,et al.  Direct and indirect contacts between cattle farms in north-west England. , 2008, Preventive veterinary medicine.

[56]  C. Webb,et al.  Farm animal networks: unraveling the contact structure of the British sheep population. , 2005, Preventive veterinary medicine.

[57]  M. Bigras-Poulin,et al.  Network analysis of Danish cattle industry trade patterns as an evaluation of risk potential for disease spread. , 2006, Preventive veterinary medicine.

[58]  L. Freeman.  Centrality in social networks conceptual clarification , 1978 .

[59]  R. Christley,et al.  Network analysis of cattle movement in Great Britain. , 2005 .

[60]  M. Keeling,et al.  Networks and epidemic models , 2005, Journal of The Royal Society Interface.