A Case-Control Seroprevalence Study on the Association Between Infection and Bipolar Disorder.

Infection with the parasite has been associated with bipolar disorder in several countries other than Mexico. Therefore, we sought to determine the association between seropositivity to and bipolar disorder in a Mexican population. We performed an age- and gender-matched case-control study of 66 patients with bipolar disorder (WHO code: F31) and 396 subjects without this disorder from the general population. Anti- immunoglobulin G (IgG) and IgM antibodies were determined using commercially available enzyme-linked immunoassays. Six (9.1%) of the 66 patients with bipolar disorder and 22 (5.6%) of the 396 controls had anti- IgG antibodies (odds ratio [OR] = 1.7; 95% confidence interval [CI] = 0.66-4.36; = 0.26). Stratification by gender and age did not show a difference in seroprevalence between cases and controls. The frequency of high (> 150 international units/ml) anti- IgG levels was similar in cases (n = 2) and in controls (n = 12) (OR = 1.0; 95% CI = 0.21-4.57; = 1.00). Stratification by F31 codes showed that patients with F31.3 code had a higher seroprevalence of infection than their age- and gender-matched controls (OR = 16.4; 95% CI = 1.25-215.09; = 0.04). None of the six anti- IgG-seropositive patients with bipolar disorder and 4 (18.2%) of the 22 anti- IgG-seropositive controls had anti- IgM antibodies ( = 0.54). Our results suggest that seropositivity is not associated with bipolar disorder in general. However, a specific type of bipolar disorder (F31.3) might be associated with seropositivity. Further research to elucidate the role of infection in bipolar disorder is needed.