Evolutionary Consequences of Feedbacks Between
Within-host Competition and Disease Control

Location       Princeton, New Jersey
Date               June 9-10, 2019 (ahead of the EEID meeting, June 10-13)
Organizers   Nicole Mideo & Megan Greischar, University of Toronto

How to Apply
Submit your CV and a cover letter (1 page maximum) describing your interest in participating in this workshop, including relevant background/data/models and the types of questions that most interest you. Please email your full application by March 31, 2019 to nicole.mideo@utoronto.ca, with the subject line ‘2019 RCN-IDEAS Workshop.’

** Accepted applicants will receive funding for transportation to/from Princeton, accommodation and meals during the workshop, and the EEID conference registration fee (note that accommodation and meals during the conference are not covered) **

Summary
Health interventions and within-host competition are two of the most potent sources of selection on parasites. Each has some well characterized effects on parasite traits: the evolution of resistance is a predictable consequence of drug treatment, while competition within a host drives the evolution of virulence (either higher or lower, depending on the system). Yet the feedbacks between these processes have only partially been mapped. For instance, competition within an infection can influence the efficacy of drug treatment and the likelihood of a resistant mutant spreading, but the best ways to exploit or mimic competitive effects to slow resistance evolution are unclear. Similarly, disease control efforts – when effective – can reduce the prevalence of infection, which should alter the frequency of coinfection and thus the fitness landscape for virulence, yet few predictions about the efficacy of control measures account for the role of such epidemiological feedbacks in modulating disease severity.

Goal
This workshop aims to bring together evolutionary biologists, disease ecologists, epidemiologists, and microbiologists to understand the scope and implications of feedbacks between within-host competition and disease control efforts. Focal questions will be generated at the meeting based on participant interest, but possible topics include the following.

• When is single- versus multiple-infection a useful dichotomy, and when is it necessary to consider a continuum of infection outcomes based on parasite diversity within the host?
• How does coinfection alter key epidemiological parameters (transmission rate and infection duration)? Are there predictable patterns across systems?
• When does diversity of infection, in the absence of variation in resistance, influence treatment outcomes?
• To what extent do mechanisms underlying competition need to be understood in order to be exploited for public health gain? Are there systems for which that level of understanding has been achieved?
• Is there a predictable relationship between prevalence of infection and frequency of coinfection?
• Given that many public health interventions exert direct selection on parasite traits (e.g., selection for resistance under drug treatment), are there cases where the potential for indirect selection via epidemiological feedbacks will be particularly important?

Researchers with relevant datasets, mathematical models, or statistical tools will work in breakout sessions organized around these focal questions (or others, depending on the interest of participants), identifying the most fruitful approaches for answering them.

Invited participants include

• Helen Alexander (Oxford)
• Farrah Bashey-Visser (Indiana University)
• Sebastian Bonhoeffer (ETH Zurich)
• Mary Bushman (Emory University)
• Lauren Childs (Virginia Tech)
• Andrew Read (Penn State)
• Nina Wale (University of Michigan)
• Helen Wearing (University of New Mexico)
• Pamela Yeh (UCLA)