Is Toxoplasma gondii infection protective against multiple sclerosis risk?

BACKGROUND: Parasitic infections may play a protective role in neurodegenative diseases. OBJECTıVE: To determine the association between Toxoplasma gondii (T. gondii) infection and Multiple Sclerosis (MS).

METHODS: One hundred fifteen patients with MS were included in the study. Sixty age and gender-matched healthy subjects were recruited as controls. Subjects were assessed for clinical and demographic parameters. The presence of specific IgG antibodies against T. gondii microorganism was searched by using an enzyme immunoassay test in the sera of the subjects.

RESULTS: T. gondii seropositivity was found to be lower in MS patients than in healthy controls (33.9% vs. 55%, p=0.007). Mean age and disease duration of the patients were 41.15±11.20 (18-74) and 1.90±1.44 (0-6) years, respectively. MS patients with a high IgG titer had lower expanded disability status scale (EDSS) scores (p=0.001) and lower annualized relapse rates (ARR) (p=0.005). There was no significant association between T. gondii seropositivity and disease duration (p=0.598). Female MS patients tended to have higher T. gondii seropositivity than males although the difference did not reach statistical significance (p=0.192). We found a negative correlation between T. gondii seropositivity and both EDSS scores (r=-0.322, p<0.001) and ARR (r=-0.263, p=0.004). CONCLUSıON: We found a negative association between T. gondii infection and the presence of MS. Furthermore, parasite infected MS patients had experienced fewer relapses with lower disability scores supporting the hypothesis of immunomodulatory effects of parasitic infections in autoimmune diseases. Further studies are required to establish the protective role of parasitic infections in MS.