Related Experiment Video
Updated: Apr 6, 2026

Diagonal Method to Measure Synergy Among Any Number of Drugs
Published on: June 21, 2018
Complex dynamics of synergistic coinfections on realistically clustered networks
Laurent Hébert-Dufresne1, Benjamin M Althouse2
1Santa Fe Institute, Santa Fe, NM 87501; laurent@santafe.edu.
Abstract:
We investigate the impact of contact structure clustering on the dynamics of multiple diseases interacting through coinfection of a single individual, two problems typically studied independently. We highlight how clustering, which is well known to hinder propagation of diseases, can actually speed up epidemic propagation in the context of synergistic coinfections if the strength of the coupling matches that of the clustering. We also show that such dynamics lead to a first-order transition in endemic states, where small changes in transmissibility of the diseases can lead to explosive outbreaks and regions where these explosive outbreaks can only happen on clustered networks. We develop a mean-field model of coinfection of two diseases following susceptible-infectious-susceptible dynamics, which is allowed to interact on a general class of modular networks. We also introduce a criterion based on tertiary infections that yields precise analytical estimates of when clustering will lead to faster propagation than nonclustered networks. Our results carry importance for epidemiology, mathematical modeling, and the propagation of interacting phenomena in general. We make a call for more detailed epidemiological data of interacting coinfections.
Insights
Network clustering can accelerate disease spread during synergistic coinfections, contrary to expectations. This occurs when coupling strength matches clustering, potentially causing explosive outbreaks on clustered networks.
Area of Science:
- Epidemiology
- Mathematical Biology
- Network Science
Background:
- Coinfection dynamics and contact network structures are typically studied separately.
- Disease propagation is generally hindered by contact network clustering.
Purpose of the Study:
- To investigate how contact structure clustering affects the dynamics of multiple interacting diseases.
- To explore the conditions under which clustering can accelerate epidemic spread in coinfection scenarios.
Main Methods:
- Developed a mean-field model for coinfection of two diseases with susceptible-infectious-susceptible dynamics.
- Analyzed interactions on modular networks and introduced a tertiary infection criterion.
Main Results:
- Clustering can unexpectedly speed up epidemic propagation in synergistic coinfections when coupling strength matches clustering.
- Observed first-order transitions in endemic states, leading to explosive outbreaks.
- Identified clustered networks as unique locations for explosive outbreaks under specific conditions.
Conclusions:
- Clustering's impact on disease dynamics is complex and context-dependent, especially in coinfection scenarios.
- Results highlight the importance of considering network structure in epidemiological models.
- Called for more detailed epidemiological data on interacting coinfections.
Related Concept Videos
Combined Effects of Drugs: Synergism
Such synergistic combinations...
Viral Recombination
Infectious Diseases and Their Occurrence
Causality in Epidemiology
Microbial Interactions: Cooperation
Microbial Interactions: Mutualism

