Better together: Tracing contacts and genes to monitor how infectious diseases spread

Merging genomic and contact network techniques could shed light on how animal behavior influences the spread of infectious diseases

As part of a commitment by more than 30 scientific, technical and medical publishers, Brill has put together a free access COVID-19 related Collection of relevant publications.

One of the studies made freely available under this initiative is a review in the journal Behaviour of two different techniques for studying the spread of infectious diseases in animals. The first involves investigating the contact that individual animals make with others to establish ‘contact networks’ that can help to map disease transmission. This is similar to the contact tracing that health authorities are conducting during the COVID-19 pandemic. The second involves tracing the genetic fingerprints of the pathogen and host animals to establish how and where a disease has spread.

Strikingly, the review suggests that using genomic and contact network approaches together could lead to new insights into factors that drive disease transmission, such as animal behavior, that are not possible using either technique alone.

Here, we talk to first author of the review, Marie Gilbertson, Doctor of Veterinary Medicine at the University of Minnesota, United States.

Congratulations on the recent publication of this timely review. What were your key findings?
Our objective was to provide an overview of how network and genomic approaches shed light on the role of animal behavior in disease transmission, and then highlight research questions and techniques that might particularly benefit from integrating these approaches. One of our main conclusions was that recent advances in using pathogen genetic data allow us to estimate “who transmitted the disease to whom.” This is hugely valuable in better understanding factors that drive disease transmission, such as animal behavior.

What are the advantages of integrating the two approaches? Do you think that this integrated approach will become more common in the future?
Network and genomic approaches are both rapidly expanding areas of research that are important in understanding infectious disease dynamics. Each provide a wealth of valuable information about factors that drive disease transmission. Yet techniques from these two fields are not usually integrated, despite their potential to provide new insights. For instance, contact networks allow researchers to study the role of variability in animal social behavior in transmission. As statistical techniques continue to improve and genomic sequencing costs are reduced, I absolutely anticipate that integration of these fields will become more common in the future.

Why are these findings significant?
Some individuals in an animal population have many more ‘contacts’ than others and some behaviors may be more conducive to transmission. These factors can have important consequences during epidemics. Integrating contact network data with genomic data allows researchers to make important conclusions about specific behaviors or even individual animals that may be important for transmission, and sheds light on how we can better control pathogens in animal populations.
For example, researchers in New Zealand who examined livestock movements using contact networks, and strain-sharing between farms using genomic data, found that livestock movements are a key factor for transmission between farms. This kind of information is tremendously helpful for targeting disease control efforts.

Is the spread of infectious diseases in animal populations relevant to a pandemic in human society?
The majority of emerging and re-emerging infectious diseases in humans are zoonotic (they originate in animals) and the majority of these originate in wildlife. COVID-19 is a perfect example of this, as the causative virus, SARS-CoV-2, appears to have ‘spilled over’ to humans from wildlife. Therefore, it’s critical that we better understand transmission within wildlife so we can understand how, when, and why these pathogens spill over into humans.

Can these techniques help us to deal with the current pandemic and be better prepared for the next one?
Many of these techniques were initially developed for human disease systems so they are certainly relevant to understanding and managing disease in humans as well as animals. In the context of the current pandemic, it may be possible to link contact tracing and other behavioral data from outbreak clusters with transmission data from those same clusters to better understand the types of interactions that are most important for transmission. This could then help us determine how best to target control measures and be better prepared for the next pandemic.