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The odds of contagion - Inaugural speech of Quirine ten Bosch
“We all make dozens of interactions a day. Most of the time, without any epidemiological consequences. But if one of those interactions is with someone that carries a pathogen, things might turn out differently. But what are the odds?” During her inaugural speech on March 15th, professor Quirine ten Bosch addressed those odds and the work of her chair group in addressing them in both research and education.
In the inaugural speech Quirine ten Bosch, leader of the chair group Infection and Disease Epidemiology (IDE) brought back to mind, the start of the Covid pandemic in spring 2020. “In hindsight, this was not the best time to be partying. At least not in the Netherlands.” This highlights the important concept inherent to contagion: the risk of getting infected depends on the status of the individuals you interact with, stated Ten Bosch. However, the status of individuals is changing over time and space, as outbreaks take off and come down. “Therefore, the risk of acquiring infections is dynamic. At IDE, we study many diseases in kept and wild animals. In any of those, we use quantitative approaches combined with different data sources to study transmission dynamics and inform surveillance and control efforts”, explains Ten Bosch.
Complexity of analysis
Analyzing contagious processes is an exercise in complexity, according to the IDE professor. In complexity science, the behavior of systems in which individuals interact with each other in dynamic, unpredictable ways is examined. From these small-scale interactions, system-wide behaviors can emerge. “Infectious disease outbreaks are an example of such ‘system-wide behaviors’. Fundamentally, these population-level patterns can’t be examined by studying individual components in isolation. You need to consider the whole system.” Using models and data can help to understand the dynamics. “Provided we have techniques that can couple these models to data in a meaningful way,” underlines Ten Bosch.
A good understanding of what drives uneven contributions is needed, to know where to target control efforts. Ten Bosch illustrated this in her inaugural speech by highlighting the differences observed when controlling Rift Valley Fever, Usutu and Sars-Covid19 viruses. Each of these diseases has its own unique characteristics. Modelling these diseases makes clear that different strategies are required for controlling their spread. Being aware of what works best in which situation is an important starting point for this, states Ten Bosch. “It makes a huge difference if you know whether if you need to target the individual organism or for example an event of region for effective control measures.”
Models
Since the Covid pandemic, the understanding of the reproduction ratio R has increased. To control a disease, it is vital to reduce the R value below 1. Models can be used to predict the effectiveness of potential intervention methods that can help to control pathogen. “Furthermore, with the emergence of new pathogens, as well as drug and insecticide resistance, comes the need for novel interventions. At IDE, we contribute to this challenge, by quantifying the effects of new interventions on individuals and populations. We examine novel tools, including biological control, novel vaccines, assisted recovery, and breeding for resistance, with our partners at the animal breeding and genomics group. We also use models to inform the design of vaccine efficacy trials, particularly for unpredictable, outbreak-prone diseases, such as Rift Valley Fever.”
Welfare
Animal diseases can result in various burdens, including animal and human health effects, economic losses, welfare costs, and environmental impacts. The latter are often not included in burden estimation and decision making on interventions, says Ten Bosch. The same holds true for human diseases, where frameworks that combine epidemiological with non-epidemiological outcomes, are needed. “At IDE, we work on the development of such frameworks, for diseases such as bluetongue and avian influenza, but also for human pathogens.”
Education
“At IDE, we have the knowledge in place to address infectious disease epidemiology, both in research and in education,” says professor Ten Bosch. “Like in research, in our educational efforts, collaborations play an important role, in bringing experiences from the field into the classroom and working together with our Bachelor and Master students on current challenges in animal health. Together, we aim to make an impact on the health of humans and animals, in mutual interaction.”