Virulence‐driven trade‐offs in disease transmission: A meta‐analysis *

  title={Virulence‐driven trade‐offs in disease transmission: A meta‐analysis *},
  author={Miguel A. Acevedo and Forrest P. Dillemuth and Andrew J. Flick and Matthew J Faldyn and Bret D. Elderd},
The virulence–transmission trade‐off hypothesis proposed more than 30 years ago is the cornerstone in the study of host–parasite co‐evolution. This hypothesis rests on the premise that virulence is an unavoidable and increasing cost because the parasite uses host resources to replicate. This cost associated with replication ultimately results in a deceleration in transmission rate because increasing within‐host replication increases host mortality. Empirical tests of predictions of the… 

Experimental evidence for stabilizing selection on virulence in a bacterial pathogen

The results indicate that selection favors pathogens of intermediate virulence at disease emergence in a novel host species, even when virulence and transmission are not linked to pathogen load.

Virulence constrains transmission even in the absence of a genetic trade-off

The virulence-transmission trade-off depends on within-host dynamics and on the timing of transmission, rather than on a genetic correlation, and this fundamental correlation may be easier to manipulate than previously thought.

The roles of environmental variation and parasite survival in virulence–transmission relationships

By combining developments in life-history evolution, phylogenetics, adaptive dynamics and comparative genomics, the understanding of virulence–transmission relationships across a diversity of host–parasite systems that have eluded experimental study of parasite life history is improved.

Detection, not mortality, constrains the evolution of virulence

It is shown that costs of mortality are too small to plausibly constrain the evolution of disease severity except in systems where survival is rare, and it is proposed that disease severity can be much more readily constrained by a cost of behavioral change due to the detection of infection.

Digest: Little evidence exists for a virulence‐transmission trade‐off *

A meta‐analysis of the key underlying relationships in research predicting the impact and spread of infectious disease highlights the surprising lack of empirical evidence for an evolutionary trade‐off between a pathogen's virulence and its transmission rate.

Integrating Infection Intensity into Within- and Between-Host Pathogen Dynamics: Implications for Invasion and Virulence Evolution

It is found that individual-level heterogeneity in pathogen load—a nearly ubiquitous characteristic of host-parasite interactions that is rarely considered in models of microparasites—generally reduces pathogen invasion probability and dampens virulence-transmission trade-offs in host-Parasite systems.

Coinfection with a virus constrains within‐host infection load but increases transmission potential of a highly virulent fungal plant pathogen

The results suggest that the trade‐off between within‐host infection load and transmission may be strain specific, and that the pathogen life‐history that underpin epidemics may change depending on the diversity of infection, generating variation in disease dynamics.

The interplay between host community structure and pathogen life‐history constraints in driving the evolution of host‐range shifts

A theoretical framework is developed to understand how resource competition among hosts interacts with constraints on pathogen biology in driving host shifts, and how antagonistic pleiotropy in the pathogen's ability to exploit hosts can counteract ecological selection towards host-range shifts.

Parasite-induced shifts in host movement may explain the transient coexistence of high- and low-pathogenic disease strains

It is found that when the lethargy and disease-induced mortality costs to the parasites are not high, then evolutionary bistability can arise, and either moderate or high virulence can evolve depending on the initial virulence and the magnitude of mutation.



The virulence–transmission trade-off in vector-borne plant viruses: a review of (non-)existing studies

Empirical investigations to what extent within-host viral accumulation determines the transmission rate and the virulence of vector-borne plant viruses are reviewed and the type of data that should be collected and how theoretical models can help refine testable predictions of virulence evolution are discussed.


An epidemiological model is developed where infections are dynamic processes and it is demonstrated how these dynamics generate a trade‐off between emerging epidemiological parameters and how host's immune strength modifies this trade-off and hence influences virulence evolution.

Transmission-clearance trade-offs indicate that dengue virulence evolution depends on epidemiological context

The authors show that dengue virus dynamics exhibit a trade-off between transmission and clearance rates, and show that the virus’s transmission potential is maximized at production rates associated with intermediate virulence and that the optimal production rate critically depends on d Dengue’'s epidemiological context.

The virulence–transmission relationship in an obligate killer holds under diverse epidemiological and ecological conditions, but where is the tradeoff?

It is found that the virulence–transmission relationship holds under diverse epidemiological and ecological conditions and the problem of using parasite‐induced host mortality as a “one‐size‐fits‐all” measure of virulence for horizontally transmitted parasites is highlighted.

Virulence-transmission trade-offs and population divergence in virulence in a naturally occurring butterfly parasite

Study of a protozoan parasite of monarch butterflies found that higher levels of within-host replication resulted in both higher virulence and greater transmission, thus lending support to the idea that selection for parasite transmission can favor parasite genotypes that cause substantial harm.

Virulence evolution and the trade‐off hypothesis: history, current state of affairs and the future

It is argued that the trade‐off hypothesis and its basic extensions are necessary to assess the qualitative impacts of virulence management strategies and many processes such as pathogen adaptation to within‐host competition, interactions with the immune system and shifting transmission routes, will all be interrelated making sweeping evolutionary predictions harder to obtain.

Empirical Support for Optimal Virulence in a Castrating Parasite

This is the first experimental study to demonstrate that the production of propagules is highest at intermediate levels of virulence and that parasite genetic variability is available to drive the evolution of virulent in this system.

Host–parasite interactions for virulence and resistance in a malaria model system

It was found that parasite and particularly host main effects explained most of the variance in virulence (anaemia and weight loss), resistance, resistance and transmission potential, and the possibility that host heterogeneity may affect the rate of any parasite response to selection on virulence.

Virulence in malaria: an evolutionary viewpoint.

  • M. MackinnonA. Read
  • Biology
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 2004
Data from the laboratory rodent malaria model, Plasmodium chabaudi, and field data on the human malaria parasite, P. falciparum, show that expected total lifetime transmission of the parasite is maximized in young children in whom the fitness cost of host mortality balances the fitness benefits of higher transmission rates and slower clearance rates, thus exhibiting the hypothesized virulence trade-off.