Rejection in early life is associated with high and long-lasting stress and higher incidence of infections in owl monkeys

1.BackgroundThe mothers of owl monkeys sometimes reject their new-borns. When this occurs in captive colonies, the rejected infants are manually raised by veterinarians, allowing them to survive. However, maternal rejection can induce chronic stress, which in turn is associated with infectious diseases. Rescued, rejected owl monkeys might experience high rates of stress and infections which go undetected. MethodologyTo test this hypothesis, we evaluated the connection between maternal rejection, stress and infections in owl monkeys (Aotus nancymaae) from the IVITA Center for Conservation and Reproduction of Primates (UNMSM, Peru). Specifically, we compared the stress rates and frequency of infection treatment in juveniles (19-24 months) rejected in the first month of life and controls. To assess stress, we compared cortisol levels in hair using a competitive ELISA and recorded behaviours using cameras. We analysed past medical treatments and medication to compare incidence of infection treatment in subjects. We then studied the correlation between the frequency of infection treatments and cortisol using a linear regression. ResultsRejected owl monkeys showed significantly higher cortisol levels (p=0.0123), a higher incidence of stereotypical behaviour and overeating (pacing p=0.0159; head twirling p=0.0476, eating p=0.0238) compared to controls. Rejected owl monkeys also received significantly more treatment for infections than controls per month lived (p=0.0009). Moreover, infection rates observed in this population were positively although weakly associated with concentration of cortisol in hair (R2=0.307, p=0.0075). ConclusionMaternal rejection in the first month of life is associated with high and long-lasting stress levels and infections in the IVITA owl monkey colony. IVITA owl monkeys will be a useful model for studying the long-term effects of early life stress at the population level.