title: Growth rate, transmission mode and virulence in human pathogens.
abstract: The harm that pathogens cause to hosts during infection, termed virulence, varies across species from negligible to a high likelihood of rapid death. Classic theory for the evolution of virulence is based on a trade-off between pathogen growth, transmission and host survival, which predicts that higher within-host growth causes increased transmission and higher virulence. However, using data from 61 human pathogens, we found the opposite correlation to the expected positive correlation between pathogen growth rate and virulence. We found that (i) slower growing pathogens are significantly more virulent than faster growing pathogens, (ii) inhaled pathogens and pathogens that infect via skin wounds are significantly more virulent than pathogens that are ingested, but (iii) there is no correlation between symptoms of infection that aid transmission (such as diarrhoea and coughing) and virulence. Overall, our results emphasize how virulence can be influenced by mechanistic life-history details, especially transmission mode, that determine how parasites infect and exploit their hosts.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK helen.c.leggett@gmail.com.|Department of Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK.
authors.forename: Helen C
authors.identifier: http://orcid.org/0000-0001-8758-355X
authors.initials: HC
authors.lastname: Leggett
authors.affiliation: Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Charlie K
authors.initials: CK
authors.lastname: Cornwallis
authors.affiliation: Department of Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK.
authors.forename: Angus
authors.initials: A
authors.lastname: Buckling
authors.affiliation: Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: West
mesh_terms: D000818:Animals; D005075:Biological Evolution; D018562:Disease Transmission, Infectious; D006790:Host-Parasite Interactions; D006801:Humans; D000071421:Life History Traits; D010271:Parasites / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology*; D014774:Virulence
keywords: growth; infective dose; parasites; trade-offs; transmission; virulence