Impact of infection on mate choice

• Infection by parasites can reduce individual fitness.
• Host responses to infection during mate choice are intended to avoid infection.
• We highlight the main limitations in current knowledge on infection avoidance.
• We summarize key factors that should affect infection avoidance in mate choice.
• The molecular mechanisms at the basis of infection avoidance need to be examined.

Sexual selection predicts that mate choice increases individual fitness. Infection by parasites (from eukaryotes to bacteria or viruses) can reduce this individual fitness, altering the infected individuals' sexual traits and molecular cues. In this case, one would expect to observe mechanisms for avoiding infection during mate choice. The vast majority of host responses to infection in terms of mate choice are intended to avoid infection, but the costs of mate choice can also hinder infection avoidance. This paper highlights the main limitations in current knowledge and empirical experiments, and summarizes the key factors that should be taken into account to test the hypothesis of infection avoidance in mate choice: the time of host–parasite coevolution in the biological interaction implied, the choosy sex tested (male, female or both) and the genetic background of the individuals tested.