Small‐world topology of UK racing: the potential for rapid spread of infectious agents

Abstract

Summary Reasons for performing study: The topology of the network of contacts between individuals has important effects on infectious disease dynamics within a population. Here we examine for the first time a network of contacts between training yards that occurred through racing. Objectives: To explore the topology of this network and to consider the effects of the network on the potential for disease transmission. Methods: Race data from one week was analysed. Contacts were defined as occurring between trainers that raced horses in the same race and hence one trainer could contact another trainer several times. A connection was said to exist between trainers who contacted each otherat least once. The network of contacts and connections that occurred during the study period was reconstructed and analysed. Results: All 466 trainers formed a single large network. The network of contacts had a short average path length and high clustering and was, therefore, characteristic of a ‘small world network’. The probability distribution of the number of contacts was scale‐free, whereas that for the number of connections followed a single‐scale. The effect of the network would be to increase R0, such that an agent that would tend toward extinction in a homogenously mixing population may persist in the observed network. Conclusions: The observed small world network topology has important implication for the transmission and, therefore, the control of infectious agents in this population. Potential relevance: Effective disease control and surveillance must take account of the contact structure of the population. Further studies investigating other contact definitions and other populations are now required.

Negative edges and soft thresholding in complex network analysis of resting state functional connectivity data

“…These include "small-world" behavior, in which the connection structure is more highly clustered (cliquish) compared to randomly wired networks with the same degree distribution, despite a similar overall average path length (distance between all pairs of nodes) (Watts and Strogatz, 1998;Bassett and Bullmore, 2006;Bullmore and Sporns, 2009;Wang et al, 2010a;Hayasaka and Laurienti, 2010). This property has also been observed in many other networks from fields such as genetics, protein folding, metabolism, epidemiology and transport (Watts and Strogatz, 1998;Wagner and Fell, 2001;Vendruscolo et al, 2002;Christley and French, 2003;Sienkiewicz and Hołyst, 2005;Zhang and Horvath, 2005;Braun et al, 2006;Almaas, 2007), and this deviation from the behavior of random NeuroImage 55 (2011NeuroImage 55 ( ) 1132NeuroImage 55 ( -1146 or regular graphs has led to the term "complex network" for such real-world networks. Another property observed in functional connectivity networks is the presence of relatively few, excessively highly-connected, 'hub,' nodes and many more weakly-connected nodes.…”

Descriptive and network analyses of the equine contact network at an equestrian show in Ontario, Canada and implications for disease spread

“…However, the high response rate for the questionnaire suggests that the network is fairly well characterized for horses associated with this particular show. Previous contact networks in veterinary medicine have been constructed using databases of animal movements [11, 20] or information obtained through registries [21], however, such information is not available in Ontario. Simply using a complete list of registrants at the show would not have allowed for the detailed collection of data about individual home facilities, or the identification of secondary contacts at these home facilities.…”

“…Previous equine contact networks have used a variety of definitions for connections between horses and locations, including connections between racehorse trainers while racing together [20] and connections between equine facilities as horses moved between them [11]. Co-attending the same competitions has been used previously in the UK sheep population as a proxy for a connection in network analysis [21].…”

Epidemiological and virological investigations of equine influenza outbreaks in Ireland (2010–2012)

“…Continuing to exercise horses following infection has been demonstrated to exacerbate the severity of clinical disease and increase weight loss . In a study carried out in the UK, examinations of the network of contacts between racehorses suggest that the spread of infectious diseases such as EI may occur rapidly . This is largely due to the close proximity of horses within yards and horses from different yards on the training gallops.…”