<p>Pearson’s <i>r</i> and Spearman rho correlations.</p>

This ecological correlational study examined associations between national happiness, cat density, <i>Toxoplasma gondii</i> exposure, and socioeconomic indicators across 93 countries. We hypothesized that countries with higher socioeconomic indicators (e.g., GDP, health expenditure, income level) would exhibit higher happiness levels.

In contrast, we predicted that higher <i>T. gondii</i> exposure, both acute (IgM) and chronic (IgG), would be negatively associated with national happiness. Data on happiness measures, cat density, GDP per capita, income classification, health expenditure, and <i>T. gondii</i> seroprevalence in pregnant women (as a proxy for broader population exposure) were obtained from publicly available sources. In line with our hypothesis, we found that national happiness was positively associated with cat density and some socioeconomic factors and negatively associated with IgM seroprevalence.