Social microbial transmission and public health

Microbes also open a broader perspective on how traits and information spread through populations. Microbial transmission is shaped not only by the biological compatibility between hosts and microbes, but also by the social structure of host populations.This has important implications for public health. During the COVID-19 pandemic, for example, mathematical models were widely used to understand and reduce the transmission of pathogens, with interventions often designed to minimize contacts and therefore transmission. During this time, I became a member of the provincial and national Canadian modelling teams for infectious disease management, where I developed mathematical models to evaluate different approaches to pandemic control, including the trade-offs between disease elimination and mitigation strategies and the effects of vaccination and travel restrictions.

While mathematical epidemiology has largely focused on the transmission of pathogenic agents, not all microbial transmission is harmful: social interactions are also an important route through which hosts acquire and maintain beneficial and commensal microbes. Examples include the transmission of gut microbes between mothers and offspring, the exchange of respiratory microbes through close social contact, and the transfer of skin microbes through physical contact, all of which can contribute to the acquisition and maintenance of healthy microbial communities in the human body. This raises a different biological and mathematical challenge: how can we limit the transmission of harmful pathogens while preserving or promoting the transmission of beneficial microbes? Understanding these trade-offs may also help us develop strategies to restore or steer microbial communities toward healthier states, from probiotic interventions to recovery of the microbiome following antibiotic treatment. 

More broadly, microbial transmission provides a powerful example of how adaptation can occur through pathways beyond genetic inheritance. Behaviors, cultural traits, opinions, and other forms of information can similarly spread through interactions among individuals. This raises fundamental questions about how social structure, transmission, and collective dynamics shape adaptation across biological and social populations. I am interested in developing mathematical frameworks that connect parent-to-offspring and social forms of inheritance and transmission, and in exploring how they reshape our understanding of evolution. Such a perspective moves beyond the view of evolution as a slow process driven exclusively by changes in DNA across generations, toward a view in which adaptation can occur within a lifetime and depends critically on interactions within the community.

Selected publications

Microbiome transfer from native to invasive species may increase invasion risk and shorten invasion lag
M. M. Martignoni, O. Kolodny · Proceedings of the Royal Society B, 291(2034), 20241318 · 2024

SIR+ models: Accounting for interaction-dependent disease susceptibility in the planning of public health interventions
M. M. Martignoni, A. Raulo, O. Linkovski, O. Kolodny · Scientific Reports, 14(1), 12908 · 2024

Is SARS-CoV-2 elimination or mitigation best? Regional and disease characteristics determine the recommended strategy
M. M. Martignoni, J. Arino, A. Hurford · Royal Society Open Science, 11(6), 240186 · 2024