Bipolar Disorder With Psychotic Features and Ocular Toxoplasmosis: A Possible Pathogenetic Role of the Parasite?

Toxoplasmosis in a Cohort of Italian Patients With Bipolar and Psychotic Disorders: How Infection May Affect Clinical Features?

This study investigated the seroprevalence of Toxoplasma gondii in a cohort of 101 Italian inpatients affected by mood or schizophrenia-spectrum disorders and compared clinical features between seronegative and seropositive subjects. Patients diagnosed according to DSM-5 criteria underwent clinical assessments and blood collection to test parasite-specific IgG/IgM serum levels. Twenty-eight patients (27.7%) had IgG anti-T. gondii, and none had IgM antibodies. We found higher prevalence rate in patients aged 40 years or older, as compared with younger. No significant association was detected between T. gondii and a specific diagnostic category; however, bipolar disorder (BD)-II showed the highest positivity rate (40.9%). The seropositive status was significantly associated with a lower presence of psychotic symptoms, higher number of total episodes of predominant excitatory polarity, longer illness duration, and lower severity of current episode, particularly anxiety, depressive, and withdrawal/retardation symptoms. These preliminary results seem to point out an association between chronic toxoplasmosis and a specific subtype of BD.

Evaluation of RE and B1 Genes as Targets for Detection of Toxoplasma gondii by Nested PCR in Blood Samples of Patients with Ocular Toxoplasmosis

INTRODUCTION

To evaluate B1 and RE genes as targets to detect Toxoplasma gondii, nested PCR is used in blood samples of patients with ocular toxoplasmosis.

MATERIALS AND METHODS

Following the measurement of IgG and IgM antibodies using indirect ELISA, IgG avidity and assessment of blood samples by nested PCR, the agreement between various test results was studied.

RESULTS

From 117 patients, 77 (65.81%) were found to be positive for IgG anti-Toxoplasma antibody, 12 cases were positive for both IgG and IgM, and 1 patient was positive for IgM only. The detection limit for the RE-nested PCR assay was one T. gondii tachyzoite, whereas the limit for B1-nested PCR was five tachyzoites. Nested PCR results showed higher agreement with IgM test results than IgG test results.

CONCLUSION

The results of this study showed that nested PCR of peripheral blood is a useful and non-invasive method for detection of T. gondii in patients with OT, especially in case of recently acquired infections, and RE targeted assay is more sensitive than B1 targeted assay for this purpose.

Lack of circulating toxoplasma gondii DNA in seropositive patients with bipolar or schizophrenia spectrum disorders

Toxoplasmosis has been previously associated with an increased risk of having Schizophrenia or Bipolar disorder in several epidemiological studies. The aim of this observational, cross-sectional study was to examine the seroprevalence of Toxoplasma infection in a cohort of Italian psychiatric inpatients and to verify the presence of circulating Toxoplasma gondii DNA in the seropositive subjects. Sixty-three patients affected by bipolar or schizoaffective disorders according to DSM-5 criteria were enrolled. The presence of Toxoplasma infection was firstly examined using an indirect serological method (ELFA), and three different direct PCR-based methods were performed to detect circulating DNA in the seropositive patients. The seroprevalence of infection was 28.6%, with a significant association between higher age and the infection status. PCR, nested-PCR and Real-Time PCR revealed no positive samples for Toxoplasma gondii. This result is in contrast with recent data from case-control studies that detected parasite genome in patients with different neuropsychiatric diagnosis without clinical evidence of acute toxoplasmosis. Our findings are to be interpreted with caution, because of the small sample size, the heterogeneity of enrolled patients and the observational nature of the study. Further studies are needed to better define the clinical features correlated to the seropositive status in neuropsychiatric patients.

Increased risk of bipolar disorder in patients with scabies: A nationwide population-based matched-cohort study

Both scabies and bipolar disorder (BD) are common and troublesome disorders. There are several similarities in both diseases: pruritus, a higher prevalence in crowded environments, and cytokine-mediated inflammatory processes in the pathophysiology. We conducted this nationwide population-based study to investigate the possible relationship between scabies and BD. Based on the National Health Insurance Research Database (NHIRD) of Taiwan, a total of 7096 patients with scabies were identified as a study group and 28,375 matched patients as a control. We tracked the patients in both groups for a 7-year period to identify those newly diagnosed with BD. The demographic characteristics and comorbidities of the patients were analyzed, and Cox proportional hazard regressions were performed to calculate the hazard ratio (HR) of BD. Of the 35,471 patients in this study, 183 (0.5%) patients with newly diagnosed BD were identified, with 58 (0.8%) from the scabies group and 125 (0.4%) from the control group. The patients with scabies had a higher risk of subsequent BD, with a crude hazard ratio of 1.86 and an adjusted hazard ratio of 1.55 (95% confidence interval: 1.12-2.09, P < 0.05). This study shows there is an increased risk for BD among patients with scabies. Immunopathology may contribute to this association.

Is Toxoplasma gondii a Trigger of Bipolar Disorder?

Toxoplasma gondii, a ubiquitous intracellular parasite, has a strong tropism for the brain tissue, where it forms intracellular cysts within the neurons and glial cells, establishing a chronic infection. Although latent toxoplasmosis is generally assumed to be asymptomatic in immunocompetent individuals, it is now clear that it can induce behavioral manipulations in mice and infected humans. Moreover, a strong relation has emerged in recent years between toxoplasmosis and psychiatric disorders. The link between T. gondii and schizophrenia has been the most widely documented; however, a significant association with bipolar disorder (BD) and suicidal/aggressive behaviors has also been detected. T. gondii may play a role in the etiopathogenesis of psychiatric disorders affecting neurotransmitters, especially dopamine, that are implicated in the emergence of psychosis and behavioral Toxoplasma-induced abnormalities, and inducing brain inflammation by the direct stimulation of inflammatory cytokines in the central nervous system. Besides this, there is increasing evidence for a prominent role of immune dysregulation in psychosis and BD. The aim of this review is to describe recent evidence suggesting a link between Toxoplasma gondii and BD, focusing on the interaction between immune responses and this infectious agent in the etiopathogenesis of psychiatric symptoms.

Toxoplasma infection in individuals in central Italy: does a gender-linked risk exist?

An accurate estimate of the impact of toxoplasmosis on the population in Italy is not available. We performed a cross-sectional study on individuals living in Italy to assess: (1) differences in access to Toxo testing and in the prevalence of recent and past Toxoplasma gondii infection according to gender and age, and (2) the clinical impact of disease burden on the male patient subset. Reason for testing, condition of in- or outpatient and clinical data were analysed. Between-gender differences were observed in access to the test. Immunoglobulin M (IgM) prevalence was increased in males in the age range 5-34 years [odds ratio (OR) = 2.03, 95% confidence interval (CI) 1.18-3.49, p = 0.01), with a peak at 25-34 years. In females, it decreased in the age range 20-39 years (OR = 0.49, 95% CI 0.32-0.74, p = 0.0008). The attack rate of recent infection was twice as high for males than for females. Estimates pointed out 3.3 and 1.7 events in 1000 at-risk person-years in the male and female cohorts, respectively. Most IgM-positive subjects did not experience severe forms of toxoplasmosis, with 35% having lymphadenopathy. Chorioretinitis, systemic and neurological manifestations were also observed. Our findings suggest that the acute phase of toxoplasmosis is largely unapparent or clinically mild in this area. It is also possible that the disease burden for Toxoplasma infection in Italy is underestimated. Further study should focus on information acquisition and Toxo test access in hospital units for a better estimation of the real burden of mild and severe forms of the disease.