Growth rate, transmission mode and virulence in human pathogens

Research output: Contribution to journalArticle


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.


External organisations
  • University of Cambridge
  • University of Exeter
  • University of Oxford
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Microbiology in the medical area


  • Growth, Infective dose, Parasites, Trade-offs, Transmission, Virulence
Original languageEnglish
Article number20160094
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1719
Publication statusPublished - 2017 Mar 5
Publication categoryResearch