Toxoplasma gondii Infection and Headache: A Matched Case-Control Study in a Public Hospital in Durango City, Mexico

( ) can disseminate to brain in infected hosts. Little is known about the magnitude of the association between this infection and headache. Therefore, we sought to determine the association of seropositivity and headache in patients attending neurological consultations in a public hospital in Durango City, Mexico. Through an age- and gender-matched case-control study, 105 patients suffering from headache and 105 subjects without headache were examined for anti- IgG and IgM antibodies using commercially available enzyme-linked immunoassays. Seropositive cases were analyzed for detection of DNA by polymerase chain reaction. Anti- IgG antibodies were found in five (4.8%) of the 105 cases and in seven (6.7%) of the 105 controls (odds ratio (OR) = 0.70; 95% confidence interval (CI): 0.21 - 2.28; P = 0.76). The frequency of high (> 150 IU/mL) levels of anti- IgG antibodies among anti- IgG positive individuals was significantly (P = 0.01) higher in cases (5/5) than in controls (1/7). Anti- IgM antibodies were found in one (20.0%) of the five IgG seropositive cases, and in three (42.9%) of the seven IgG seropositive controls (P = 0.60). DNA was not detected in any of the five anti- IgG positive cases. No association between infection and specific headache types was found. This is the first matched case-control study on the association between infection and headache. Results suggest that high anti- IgG antibody levels, but not seropositivity, were associated with headache in the population studied.