Impact of Network Activity on the Spread of Infectious Diseases
In this article, the researchers, Karin Lebi, Hartmut H. K. Lentz, Beate Pinior, and Thomas Selhorst, study the effects the trade of livestock can have on the spread of infectious diseases. Their research focuses on the trade network of the German pig, and how the frequency of the trade of this animal can either decrease or increase the prevalence and spread of disease. The observed German pig trade network had an activity of a=0.11, meaning that the edge between any two nodes (farms) in the network was active about 10% of the time during the observed time period of 2008-2009. Furthermore, they designed their study to access whether it would make a difference to the probability of disease outbreaks, size, and duration if they were to transport many animals at one time, or few animals many times.
Ultimately, their results demonstrated that the frequency of transports and amount of animals transported at a time did make a difference in the spread of animal diseases. They found that for transmission probabilities <1, the outbreak probability increases when there is a decreased frequency of animal transports. However, in terms of the final outbreak size, they found that this outbreak probability only affected a small number of farms. Moreover, the results of their simulation show that even small changes in the activity level of the German pig trade network could have drastic effects on outbreak size, probability and duration, therefore demonstrating that network activity is an important factor in modeling the spread of disease within trade networks.
This research speaks to our discussion of social networks and strong and weak ties. If farms begin to trade more frequently, or have a stronger connection with each other, this has an effect on the spread of animal disease. Likewise, if two farms have a weak tie, or rarely trade, this could prevent disease from spreading between these two farms.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914562/