Meeting Abstract
Sick animals often provide visible cues that they are infected through behaviors such as lethargy, and physical signs, such as inflammation and lesions. The detection and avoidance of sick conspecifics is common among animals, but less is known about how viewing diseased conspecifics influences an organism’s physiological state. Work in humans suggests that visual cues of infection are capable of stimulating the immune system, presumably to help the body prepare for an impending immune threat. Whether visual cues of disease can also induce changes in immunity in non-human organisms is not well understood, however if organisms can adjust investment in immune defenses to match the probability of pathogen exposure this could have important implications for disease transmission dynamics. The avian pathogen Mycoplasma gallisepticum (MG) is an ideal tool for investigating how the perception of social cues of disease shape immunity in healthy individuals, as infection with this bacterium causes obvious visual signs of infection, including lethargy and conjunctivitis. We tested whether social information transmitted by MG-infected individuals can stimulate innate immune responses in domestic canaries housed in visual contact with either healthy or MG-infected conspecifics. We found that immune profiles differed between birds viewing sick and healthy conspecifics. Specifically, we observed immune activation in healthy birds viewing MG-infected individuals around 6-12 days post-inoculation, which is when infected stimulus birds exhibited the greatest degree of disease pathology and lethargy. These data indicate that social cues of infection are capable of altering immune responses in healthy individuals and suggest that public information about disease could play a role in shaping individual variation in disease susceptibility.
