Association Between Toxoplasma gondii Infection and Drug Addiction: Evidence from a Case-Control Study

The neurotropic protozoan parasite Toxoplasma gondii has been linked to behavioral changes and several neuropsychiatric disorders. Given the neurobiological alterations associated with substance use disorders, this study aimed to evaluate the potential association between latent T. gondii infection and drug addiction.

In this case-control study, 210 participants (105 individuals with drug addiction and 105 healthy controls) were enrolled. Serum anti-T. gondii IgG antibodies were detected using enzymelinked immunosorbent assay (ELISA). Demographic characteristics and potential risk factors were recorded. Statistical analyses included the Mann-Whitney U test, chi-square test, and multivariate logistic regression. A P-value <0.05 was considered statistically significant.

The seroprevalence of T. gondii was significantly higher in individuals with drug addiction (25.7%) compared to controls (11.4%; P=0.007). However, in the overall multivariate analysis, drug addiction was not an independent predictor of infection (aOR=1.41, P=0.469). Age >30 years (aOR=3.84) and rural residence (aOR=2.50) were independently associated with seropositivity. Sexstratified analysis demonstrated a strong association in females (aOR=8.14, P=0.017), whereas no significant association was observed in males (aOR=0.63, P=0.454). Contact with animals was also identified as a significant risk factor, and opioid use showed the highest infection rate among substance types.

The higher seroprevalence among individuals with addiction, particularly females, suggests possible sex-specific vulnerability or exposure patterns.

Although drug addiction was not an independent predictor overall, the observed sexspecific association highlights.