Moreover, patients with viral infections or chronic inflammation have elevated circulating levels of cytokines (e.g., IL-1 and IL-6) that correlate or present with acute sickness behaviors, including fever, malaise, pain, fatigue, mood fluctuations, depressive symptoms, reduced activity, loss of interest in social activities, and even increased aggression (Zalcman and Siegel, 2006; Felger, 2018; Slavich and Irwin, 2014; Dowlati et al., 2010; Vollmer-Conna et al., 2004; Dantzer, 2023). Here, IL6 is linked to viral infectious disease.