CHRONIC SOCIAL STRESS, SOCIAL-STATUS, AND SUSCEPTIBILITY TO UPPER RESPIRATORY-INFECTIONS IN NONHUMAN-PRIMATES

Objective: The objective of the study was to assess the roles of socia l stress and social status in susceptibility to upper respiratory infe ction. Method: Sixty male cynomolgus monkeys were randomly assigned to stable or unstable social conditions for 15 months. Two markers of so cial status, social rank and percent of behaviors that were submissive , were assessed at independent observation periods. Endocrine, immune, and behavioral responses were each assessed (at 3-month intervals) du ring the 9th through 14th months of the study. At the beginning of the 15th month, all animals were exposed to a virus (adenovirus) that cau ses a common-cold-like illness. The primary outcome was whether or not an animal developed an infection (shed virus) after viral exposure. R esults: Although the social instability manipulation was associated wi th increased agonistic behavior as indicated by minor injuries and ele vated norepinephrine responses to social reorganizations, the manipula tion did not influence the probability of being infected by the virus. However, low social status (as assessed by either marker) was associa ted with a substantially greater probability of being infected. It was also associated with less body weight, greater elevated cortisol resp onses to social reorganizations, and less aggressive behavior. However , none of these characteristics could account for the relation between social status and infection. Conclusions: Social stress was not assoc iated with susceptibility to infection. However, animals with lower so cial status were at higher risk than high social status animals.