Evolution of parasite transmission dispersion

An open question in epidemiology is why transmission is often overdispersed, meaning that most new infections are driven by few infected individuals. For example, around 10% of COVID-19 cases cause 80% of new COVID-19 cases. This overdispersion in parasite transmission is likely driven by intrinsic...

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Main Authors: Hannelore MacDonald, Sebastian Bonhoeffer, Roland Regoes
Format: Article
Language:English
Published: The Royal Society 2025-01-01
Series:Royal Society Open Science
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Online Access:https://royalsocietypublishing.org/doi/10.1098/rsos.240629
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author Hannelore MacDonald
Sebastian Bonhoeffer
Roland Regoes
author_facet Hannelore MacDonald
Sebastian Bonhoeffer
Roland Regoes
author_sort Hannelore MacDonald
collection DOAJ
description An open question in epidemiology is why transmission is often overdispersed, meaning that most new infections are driven by few infected individuals. For example, around 10% of COVID-19 cases cause 80% of new COVID-19 cases. This overdispersion in parasite transmission is likely driven by intrinsic heterogeneity among hosts, i.e. variable SARS-CoV-2 viral loads. However, host heterogeneity could also indirectly increase transmission dispersion by driving parasite adaptation. Specifically, transmission variation among hosts could drive parasite specialization to highly infectious hosts. Adaptation to rare, highly infectious hosts could amplify transmission dispersion by simultaneously decreasing transmission from common, less infectious hosts. This study considers whether increased transmission dispersion can be, in part, an emergent property of parasite adaptation to heterogeneous host populations. We develop a mathematical model using a Price equation framework to address this question that follows the epidemiological and evolutionary dynamics of a general host–parasite system. The results predict that parasite adaptation to heterogeneous host populations drives high transmission dispersion early in epidemics. Furthermore, parasite adaptation can maintain increased transmission dispersion at endemic equilibria if virulence differs between hosts in a heterogeneous population. More broadly, this study provides a framework for predicting how parasite adaptation determines transmission dispersion for emerging and re-emerging infectious diseases.
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spelling doaj-art-989de1f70e2c4e9ba69ca6c1ef4c81822025-01-23T20:22:51ZengThe Royal SocietyRoyal Society Open Science2054-57032025-01-0112110.1098/rsos.240629Evolution of parasite transmission dispersionHannelore MacDonald0Sebastian Bonhoeffer1Roland Regoes2Institute for Integrative Biology, ETH Zürich, 8005 Zürich, SwitzerlandInstitute for Integrative Biology, ETH Zürich, 8005 Zürich, SwitzerlandInstitute for Integrative Biology, ETH Zürich, 8005 Zürich, SwitzerlandAn open question in epidemiology is why transmission is often overdispersed, meaning that most new infections are driven by few infected individuals. For example, around 10% of COVID-19 cases cause 80% of new COVID-19 cases. This overdispersion in parasite transmission is likely driven by intrinsic heterogeneity among hosts, i.e. variable SARS-CoV-2 viral loads. However, host heterogeneity could also indirectly increase transmission dispersion by driving parasite adaptation. Specifically, transmission variation among hosts could drive parasite specialization to highly infectious hosts. Adaptation to rare, highly infectious hosts could amplify transmission dispersion by simultaneously decreasing transmission from common, less infectious hosts. This study considers whether increased transmission dispersion can be, in part, an emergent property of parasite adaptation to heterogeneous host populations. We develop a mathematical model using a Price equation framework to address this question that follows the epidemiological and evolutionary dynamics of a general host–parasite system. The results predict that parasite adaptation to heterogeneous host populations drives high transmission dispersion early in epidemics. Furthermore, parasite adaptation can maintain increased transmission dispersion at endemic equilibria if virulence differs between hosts in a heterogeneous population. More broadly, this study provides a framework for predicting how parasite adaptation determines transmission dispersion for emerging and re-emerging infectious diseases.https://royalsocietypublishing.org/doi/10.1098/rsos.240629superspreadingparasiteevolutionepidemiology
spellingShingle Hannelore MacDonald
Sebastian Bonhoeffer
Roland Regoes
Evolution of parasite transmission dispersion
Royal Society Open Science
superspreading
parasite
evolution
epidemiology
title Evolution of parasite transmission dispersion
title_full Evolution of parasite transmission dispersion
title_fullStr Evolution of parasite transmission dispersion
title_full_unstemmed Evolution of parasite transmission dispersion
title_short Evolution of parasite transmission dispersion
title_sort evolution of parasite transmission dispersion
topic superspreading
parasite
evolution
epidemiology
url https://royalsocietypublishing.org/doi/10.1098/rsos.240629
work_keys_str_mv AT hanneloremacdonald evolutionofparasitetransmissiondispersion
AT sebastianbonhoeffer evolutionofparasitetransmissiondispersion
AT rolandregoes evolutionofparasitetransmissiondispersion