Death is overrated: the potential role of detection in driving virulence evolution. Issue 1995 (29th March 2023)

• Record Type: Journal Article
• Authors: Kennedy, David A.
• Is Part Of: Proceedings. Volume 290:Issue 1995(2023)
• Publication Date: 2023-03-29
• Subjects: evolution of virulence -- virulence–transmission trade-off -- detection cost -- mortality cost -- pathogen evolution; Biology -- Periodicals; 570.5
• DOI: 10.1098/rspb.2023.0117
• Languages: English
• ISSNs: 0962-8452

Abstract

Abstract : A common assumption in the evolution of virulence theory literature is that pathogens transmit better when they exploit their host more heavily, but by doing so, they impose a greater risk of killing their host, thus truncating infectious periods and reducing their own opportunities for transmission. Here, I derive an equation for the magnitude of this cost in terms of the infection fatality rate, and in doing so, I show that there are many cases where mortality costs are too small to plausibly constrain increases in host exploitation by pathogens. I propose that pathogen evolution may often be constrained by detection costs, whereby hosts alter their behaviour when infection is detectable, and thus reduce pathogen opportunities for onward transmission. I then derive an inequality to illustrate when mortality costs or detection costs impose stronger constraints on pathogen evolution, and I use empirical data from the literature to demonstrate that detection costs are frequently large in both human and animal populations. Finally, I give examples of how evolutionary predictions can change depending on whether costs of host exploitation are borne out through mortality or detection.