Prevalence of Toxoplasma gondii infection among individuals with severe mental illness in Nigeria: a case control study

Abstract

Background: While the aetiology for most psychotic disorders is unknown, a strong association has been observed between Toxoplasma gondii infection and psychosis. The proportion of individuals with psychotic disorders who have current or past infection with toxoplasma has been varied. Reports from the African continent have however been scanty.

Methods: A case control study of patients with a psychotic disorder presenting for the first time to a regional psychiatric facility was undertaken and compared to age and sex-matched healthy controls. In addition to socio-demographic and clinical characteristics, seroprevalence (IgG and IgM) of T. gondii was undertaken using an immunoassay test kit.

Results: IgG seropositivity was significantly higher among cases (30·7% vs 17·85%, OR = 2·04, 95% CI = 1·12-3·74, P<0·02). In contrast, IgM seropositivity was significantly lower among the cases (7·14% vs 8·57%, OR = 0·82, 95% CI = 0·31-2·16, P = 0·82). Cases who were IgG seropositive to T. gondii were more likely to be older (P<0·001) and female (P<0·001). There was no statistically significant difference in terms of T. gondii infection and, eaten poorly cooked meat (0·88), and diagnostic group (P = 0·53). Though there was a trend towards exposure to cats, this failed to reach significance (P = 0·08).

Conclusion: T. gondii (IgG) infection is common among individuals with severe mental illness sampled and significantly higher compared to controls.