From Infection to Anxiety: A Sequential Model Linking Latent Toxoplasmosis to Psychological Distress via Health and Stress.

Identifying the drivers of chronic stress is crucial for understanding its impact on mental health. Latent toxoplasmosis, a widespread parasitic infection, has been linked to various psychological changes. The Stress-Coping Hypothesis proposes that at least some of these changes are consequences of chronic stress arising from the infection's negative impact on physical health, rather than direct parasitic manipulation. To test this mediational pathway, we surveyed 1768 individuals previously tested for toxoplasmosis or borreliosis, using the Perceived Stress Scale and the State-Trait Anxiety Inventory. As predicted, Toxoplasma-infected individuals reported significantly poorer physical health and higher levels of perceived stress and anxiety. Crucially, path analysis revealed a clear sequential mechanism: toxoplasmosis was directly associated only with poorer physical health, which in turn predicted higher perceived stress, which subsequently predicted increased anxiety. This specific, stress-mediated pathway was absent in the control group of individuals with borreliosis, providing strong evidence that the psychological effects of this common infection are side effects of illness-induced chronic stress. These findings offer a mechanistic model of how a chronic physical health burden translates into significant psychological distress and highlight the importance of considering latent infections as a contributor to the global burden of stress-related disorders.