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Coexistence of pathogens in sexually-transmitted disease models
Jia Li1, Zhien Ma, Steve P Blythe
1Department of Mathematical Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA. li@math.uah.edu
Abstract:
We present a sexually-transmitted disease (STD) model for two strains of pathogen in a one-sex, heterogeneously-mixing population, where the dynamics are of SIS (susceptible/infected/susceptible) type, and there are two different groups of individuals. We analyze all equilibria for the case where contacts are modeled via proportionate (random) mixing. We find that both strains may under suitable circumstances coexist, and that it is the heterogeneous mixing that creates "refuges" for each strain as each population group favors one particular strain.
Insights
This study models two sexually-transmitted disease strains in a single-sex population. Heterogeneous mixing creates refuges, allowing both strains to coexist by favoring different population groups.
Area of Science:
- Epidemiology
- Mathematical Modeling
- Population Dynamics
Background:
- Sexually-transmitted diseases (STDs) pose significant public health challenges.
- Understanding pathogen dynamics in heterogeneous populations is crucial for control strategies.
- Previous models often simplify population mixing, potentially missing key epidemiological features.
Purpose of the Study:
- To develop and analyze a mathematical model for two co-circulating STD strains.
- To investigate the impact of heterogeneous population mixing on STD dynamics.
- To determine conditions for the coexistence of multiple pathogen strains.
Main Methods:
- Development of a Susceptible-Infected-Susceptible (SIS) compartmental model.
- Analysis of model equilibria under proportionate (random) mixing assumptions.
- Incorporation of two distinct population groups with differential contact rates.
Main Results:
- Identification of all possible equilibrium states for the STD model.
- Demonstration that both pathogen strains can coexist under specific conditions.
- Evidence that heterogeneous mixing creates 'refuges' for each strain, with distinct groups favoring different strains.
Conclusions:
- Heterogeneous mixing is a critical factor in the coexistence of multiple STD strains.
- Population structure can lead to niche formation, supporting pathogen diversity.
- The model provides insights into STD persistence and the potential for multi-strain infections.