Avoidance of infection.

Since our first understanding of the nature of pathogen and parasite transmission, avoidance of infectious diseases has been an essential component of public health and epidemic suppression. Avoidance reduces an individual's risk of contacting pathogens. Humans are not the only host organisms that avoid their pathogens and parasites, though. In nature, infection avoidance is widespread in vertebrates, invertebrates, and even plants. Examining avoidance from this unified taxonomic perspective gives insights into its function, form, evolution, and application. In this Primer, we functionally define avoidance, outline its taxonomic breadth, provide an overview of what is known about its mechanisms and evolution, and identify applications of basic avoidance knowledge across fields as diverse as public health, conservation, and agriculture. We also highlight key open questions directing research into the future.