Association between schizophrenia and Toxoplasma gondii infection in Algeria

Molecular Mimicry between Toxoplasma gondii B-Cell Epitopes and Neurodevelopmental Proteins: An Immunoinformatic Approach

Epidemiological studies and meta-analyses have shown a strong association between high seroprevalence of Toxoplasma gondii (T. gondii) and schizophrenia. Schizophrenic patients showed higher levels of anti-Toxoplasma immunoglobulins M and G (IgM and IgG) when compared to healthy controls. Previously, in a rat model, we demonstrated that the progeny of mothers immunized with T. gondii lysates before gestation had behavioral and social impairments during adulthood. Therefore, we suggested that T. gondii infection can trigger autoreactivity by molecularly mimicking host brain proteins. Here, we aimed to identify the occurrence of antigenic mimicry between T. gondii epitopes and host brain proteins. Using a bioinformatic approach, we predicted T. gondii RH-88 B cell epitopes and compared them to human cell-surface proteins involved in brain development and differentiation (BrainS). Five different algorithms for B-cell-epitope prediction were used and compared, resulting in 8584 T. gondii epitopes. We then compared T. gondii predicted epitopes to BrainS proteins by local sequence alignments using BLASTP. T. gondii immunogenic epitopes significantly overlapped with 42 BrainS proteins. Among these overlapping proteins essential for brain development and differentiation, we identified HSP90 and NOTCH receptors as the proteins most likely to be targeted by the maternally generated pathogenic antibodies due to their topological overlap at the extracellular region of their sequence. This analysis highlights the relevance of pregestational clinical surveillance and screening for potential pathogenic anti-T. gondii antibodies. It also identifies potential targets for the design of vaccines that could prevent behavioral and cognitive impairments associated with pre-gestational T. gondii exposure.

Correlation between toxoplasmosis and schizophrenia in Egyptian patients and its impact on dopamine serum levels

Toxoplasma gondii, a parasite infecting around one-third of the global population, has been linked to neurological disorders like schizophrenia. Abnormal dopamine levels are linked to the pathophysiology of schizophrenia, but their association remains unclear. This study aimed to investigate the relationship between T. gondii seroprevalence and dopamine serum levels in schizophrenic patients in Egypt. This case-control study included 93 patients diagnosed with schizophrenia and 93 individuals as controls. T. gondii seroprevalence was determined using an enzyme-linked immunosorbent assay (ELISA). Dopamine serum levels were measured using ELISA. Sociodemographic and clinical characteristics were also collected. The study found a higher prevalence of T. gondii IgG antibodies in patients with schizophrenia (68 %) compared to controls (46.2 %). Contact with cats, sausage consumption, and undercooked meat were identified as possible risk factors associated with T. gondii infection. The mean level of serum dopamine was significantly (P < 0.001) higher in patients with schizophrenia (115.3 Pg/ml ±31.8) compared to the control group (75.02 Pg/ml ±26.5). The study found that schizophrenic patients with T. gondii seropositivity had significantly higher dopamine serum levels (mean=145.2 ± 32.1 pg/ml) than those without T. gondii seropositivity (mean=122.5 ± 29.7 pg/ml) (p = 0.001). Logistic regression analysis revealed that T. gondii seropositivity was a significant predictor of increased dopamine serum levels in schizophrenic patients (odds ratio=3.4, 95 % confidence interval=1.8-6.4, p < 0.001). The study suggests that T. gondii seroprevalence may increase dopamine serum levels in Egyptian schizophrenic patients, potentially contributing to dopamine dysregulation in schizophrenia, but further research is needed to confirm these findings and investigate the underlying mechanisms.

Toxoplasma gondii infection positively associated with schizophrenia: Evidences from UK Biobank cohort and case-controlled studies

Toxoplasma gondii (T. gondii) is an opportunistic pathogen affecting about 1/3 of world population. While often asymptomatic in immunocompetent individuals, it can lead to severe toxoplasmosis in immunocompromised patients. Recent research has unveiled a potential link between T. gondii infection and neuropsychiatric diseases. We implemented both a cohort study and a case control study to further identify this association. In the cohort study, we analyzed data from the UK Biobank database, which included 8814 individuals tested for T. gondii SAG1 antibodies and free of neuropsychiatric disorders at baseline. Among them, 22.52% (n = 1985) tested positive for SAG1 antibody. Over an average follow-up period of 12.26 years, Cox proportional hazards models and logistic regression analysis revealed a significant association between the SAG1 seropositivity at baseline and the incidence of schizophrenia (HR: 5.89; 95% CI: 1.69-20.53). In our case-control study, 239 patients diagnosed with schizophrenia and 455 healthy individuals were involved. Using the modified agglutination test (MAT) to detect T. gondii antibodies, logistic regression analysis showed a higher prevalence of T. gondii infection among schizophrenia patients (10.04%) compared to healthy controls (3.74%). T. gondii infection emerged as a significant risk factor for schizophrenia (OR: 3.33; 95% CI: 1.68-6.61). However, our investigations did not reveal a robust association between T. gondii infection and other neuropsychiatric conditions, including Alzheimer's disease, dementia, anxiety, depression, neurodegenerative disorders, and peripheral neurological disorders such as neurological and plexus disorders.

Seroprevalence and Associated Risk Factors of Toxoplasma gondii in Patients Diagnosed with Schizophrenia: A Case-Control Cross Sectional Study

The protozoan parasite, Toxoplasma gondii, has been linked to several psychiatric disorders, including schizophrenia. The aim of this study was to assess the prevalence of T. gondii IgG antibodies and risk factors associated with seroprevalence in patients diagnosed with schizophrenia. This seroepidemiological study assessed 196 participants, divided into two groups. The study group consisted of 98 schizophrenic patients and was matched with 98 healthy blood donors. A questionnaire was used to gather information regarding potential risk factors associated with T. gondii seroprevalence. Results revealed a higher seroprevalence of T. gondii IgG antibodies in schizophrenic patients (69.39%, 68/98) when compared to healthy controls (51.02%, 50/98) (OR: 2.18; 95% CI: 1.21-3.9; p = 0.01). Patients with schizophrenia who consumed raw or undercooked meat (80.65%, 25/31) (OR: 3.75; 95% CI: 1.25-11.21, p = 0.02) and those with a lower educational level (77.59%, 45/58) (OR: 3.5; 95% CI: 1.59-7.54, p = 0.002) presented increased T. gondii seropositivity rates versus their control counterparts. Our findings indicate a high T. gondii IgG seroprevalence in patients diagnosed with schizophrenia compared to healthy blood donors. Factors associated with T. gondii seroprevalence were consumption of raw or uncooked meat and a lower educational attainment. This study provided the first data regarding the potential risk factors for toxoplasmosis in Romanian patients diagnosed with schizophrenia and may serve as a foundation for future research and the development of preventive strategies.

Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis

BACKGROUND

It has been proposed that cat ownership may be a risk-modifying factor for schizophrenia-related disorders and psychotic-like experiences (PLE). This study aimed to systematically review and meta-analyze publications that reported the relationship between cat ownership and schizophrenia-related outcomes.

METHODOLOGY

We searched Medline, Embase, CINAHL, Web of Science, and gray literature for publications between January 1, 1980, and May 30, 2023, regardless of geographical location and language. Backward citation search methods were used to locate additional articles. We included studies that reported original data on cat ownership and schizophrenia-related outcomes. We meta-analyzed estimates based on broad definitions (cat ownership, cat bites, and cat contact) with estimates with or without covariate adjustments. We pooled comparable estimates using random-effects models and assessed the risk of bias, heterogeneity, and study quality.

RESULTS

We identified 1915 studies, of which 106 were chosen for full-text review, ultimately resulting in the inclusion of 17 studies. We found an association between broadly defined cat ownership and increased odds of developing schizophrenia-related disorders. For the studies reporting unadjusted odds ratios (OR; n = 10), the pooled OR was 2.14 (95% CI: 1.29-3.55). Exclusion of one outlier study resulted in a pooled OR (n = 9) of 1.56 (95% CI: 1.27-1.92). For the studies reporting adjusted estimates (n = 5), the pooled OR was 2.44 (95% CI: 1.59-3.73). After excluding one study with suboptimal exposure/design features, the pooled adjusted OR (n = 4) was 2.40 (95% CI: 1.50-3.86). We were unable to aggregate the estimates for the PLE outcomes because of the broad range of measures.

CONCLUSIONS

Our findings provide support for the hypothesis that cat exposure is associated with an increased risk of broadly defined schizophrenia-related disorders; however, the findings related to PLE as an outcome are mixed. There is a need for more high-quality studies in this field.

PROSPERO REGISTRATION

PROSPERO 2023 CRD42023426974. Available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023426974.

Associations between Toxoplasma gondii seropositivity and psychopathological manifestations in schizophrenic patients: A single-center study from Ecuador

BACKGROUND

Schizophrenia, a complex neuropsychiatric disorder, is believed to be influenced by various factors including environmental exposures. A potential environmental factor is the infection by the obligate intracellular parasitic protozoan, Toxoplasma gondii which affects neurotransmitter levels, which could potentially exacerbate, trigger symptoms of schizophrenia or make them worst.

OBJECTIVE

To investigate the association between Toxoplasma gondii seropositivity and psychopathological presentation in persons with schizophrenia in Ecuador.

METHODS

This study was conducted at the Neuroscience Institute of Guayaquil, Ecuador. Among 368 inpatients, 104 were selected based on specific inclusion and exclusion criteria. Descriptive statistics captured patient characteristics and mental health outcomes. Logistic regression models estimated the effect of toxoplasmosis on various mental health outcomes, controlling for demographic and health-related variables.

RESULTS

86.5% of participants were seropositive for toxoplasmosis. Toxoplasma-seropositive schizophrenic patients had a lower risk of depression but a significantly higher risk of disorientation. The most prevalent mental health outcomes were Language Impairments (70.2%) and Bizarre Behavior (76.0%).

CONCLUSION

Our findings suggest that Toxoplasma gondii seropositivity may have specific effects on mental functions in schizophrenic patients, particularly reducing the risk of depression but increasing the risk of disorientation. Further studies are required to clarify these associations and the potential underlying mechanisms.

Prevalence of Toxoplasma gondii IgG Antibodies and Associated Risk Factors in Psychiatric Patients from Western Romania: A Cross-Sectional Study

Infection with the coccidian parasite Toxoplasma gondii was associated with an increased risk of several mental disorders. We conducted a case-control study of 464 consecutive psychiatric patients and assessed the prevalence of IgG antibodies against T. gondii and the potential risk factors associated with infection. T. gondii-specific antibodies were determined using a chemiluminescence assay. A questionnaire was utilized to assess the potential correlation between risk factors and Toxoplasma gondii seropositivity. IgG antibodies were found in 325 (70.04%) of the patients. We observed a higher likelihood of positive IgG antibodies against Toxoplasma gondii in older individuals, patients residing in rural areas, and females. We also noted associations between Toxoplasma gondii infection and certain risk factors, like activities that involve contact with soil, low-income levels, and limited educational attainment. Our findings indicate a high prevalence of T. gondii infection among psychiatric patients from Western Romania and provide new information regarding the potential risk factors associated with T. gondii in this population group. This study may serve as a foundation for future research and the development of preventive strategies.

Global seroprevalence of Toxoplasma gondii infection among patients with mental and neurological disorders: A systematic review and meta-analysis

Background and Aim

Toxoplasmosis is the most widespread zoonotic disease that affects one-third of the world's population, and imposes a major public health problem worldwide. This study aimed to assess the prevalence of toxoplasmosis among patients with neuropsychiatric patients.

Methods

Electronic databases PubMed, Google Scholar, Web of Science, Research Gate, and Scopus were thoroughly searched from February to March 2022 to identify all relevant studies. The quality of studies was evaluated using the Newcastle-Ottawa quality scale for case-control and cross-sectional studies. Statistical analysis was done using STATA version 12 software. A random effect model was used to compute the global pooled seroprevalence of Toxoplasma gondii infection. Heterogeneity was quantified by using I 2 value. Subgroup analysis was done, and publication bias was assessed using a funnel plot and Egger's test.

Result

Of 1250 studies, 49 containing 21,093 participants and conducted in 18 countries were included. The global pooled seroprevalence of T. gondii IgG antibody was 38.27% (95% CI: 32.04-44.9) among neuropsychiatric patients and 25.31% (95% CI: 21.53-29.08) in healthy controls with substantial heterogeneity of 98.3%. The prevalence of T. gondii IgG antibody was higher in males (17.52%) than in females (12.35%) neuropsychiatric patients. The highest pooled prevalence of T. gondii IgG antibody was in Europe (57%) followed by Africa (45.25%) and Asia (43%). Time based analysis showed the highest pooled prevalence of T. gondii IgG antibody in 2012-2016 (41.16%).The global pooled seroprevalence T. gondii IgM antibody among neuropsychiatric patients and healthy controls was 6.78% (95% CI: 4.87-8.69) and 3.13% (95% CI: 2.02-4.24), respectively.

Conclusion

The pooled prevalence of chronic and acute T. gondii infection among neuropsychiatric patients was 38.27% and 6.78%, respectively. This showed a high burden of toxoplasmosis among neurological and psychiatric patients and urges routine screening of those patients and providing appropriate treatment. It also indicates the need for different stakeholders to develop targeted prevention and control strategies for T. gondii infection.

Neuroimmunology of Common Parasitic Infections in Africa

Parasitic infections of the central nervous system are an important cause of morbidity and mortality in Africa. The neurological, cognitive, and psychiatric sequelae of these infections result from a complex interplay between the parasites and the host inflammatory response. Here we review some of the diseases caused by selected parasitic organisms known to infect the nervous system including Plasmodium falciparum, Toxoplasma gondii, Trypanosoma brucei spp., and Taenia solium species. For each parasite, we describe the geographical distribution, prevalence, life cycle, and typical clinical symptoms of infection and pathogenesis. We pay particular attention to how the parasites infect the brain and the interaction between each organism and the host immune system. We describe how an understanding of these processes may guide optimal diagnostic and therapeutic strategies to treat these disorders. Finally, we highlight current gaps in our understanding of disease pathophysiology and call for increased interrogation of these often-neglected disorders of the nervous system.

Deciphering the Role of Protein Phosphatases in Apicomplexa: The Future of Innovative Therapeutics?

Parasites belonging to the Apicomplexa phylum still represent a major public health and world-wide socioeconomic burden that is greatly amplified by the spread of resistances against known therapeutic drugs. Therefore, it is essential to provide the scientific and medical communities with innovative strategies specifically targeting these organisms. In this review, we present an overview of the diversity of the phosphatome as well as the variety of functions that phosphatases display throughout the Apicomplexan parasites’ life cycles. We also discuss how this diversity could be used for the design of innovative and specific new drugs/therapeutic strategies.

Neurological and Neurobehavioral Disorders Associated with Toxoplasma gondii Infection in Humans

The intracellular parasite Toxoplasma gondii is estimated to infect up to 30% of the world population, leading to lifelong chronic infection of the brain and muscle tissue. Although most latent T. gondii infections in humans have traditionally been considered asymptomatic, studies in rodents suggest phenotypic neurological changes are possible. Consequently, several studies have examined the link between T. gondii infection and diseases such as schizophrenia, epilepsy, depression, bipolar disorder, dysphoria, Alzheimer's disease, Parkinson's disease, and obsessive-compulsive disorder (OCD). To date, there is varying evidence of the relationship of T. gondii to these human neurological or neurobehavioral disorders. A thorough review of T. gondii literature was conducted to highlight and summarize current findings. We found that schizophrenia was most frequently linked to T. gondii infection, while sleep disruption showed no linkage to T. gondii infection, and other conditions having mixed support for a link to T. gondii. However, infection as a cause of human neurobehavioral disease has yet to be firmly established.

Association between Toxoplasma gondii Exposure and Suicidal Behavior in Patients Attending Primary Health Care Clinics

This study aimed to determine the association between suicidal behavior and T. gondii seroreactivity in 2045 patients attending primary care clinics. IgG antibodies against T. gondii were found in 37 (12.1%) out of 306 individuals with a history of suicidal ideation and in 134 (7.7%) of 1739 individuals without this history (OR: 1.64; 95% CI: 1.11–2.42; p = 0.01). Seropositivity to T. gondii was associated with suicidal ideation in women (OR: 1.56; 95% CI: 1.01–2.42; p = 0.03) and individuals aged ≤30 years (OR: 3.25; 95% CI: 1.53–6.88; p = 0.001). No association between the rates of high (>150 IU/mL) levels of anti-T. gondii IgG antibodies and suicidal ideation or suicide attempts was found. IgG antibodies against T. gondii were found in 22 of 185 (11.9%) individuals with a history of suicide attempts and in 149 (8.0%) of 1860 individuals without this history (OR: 1.54; 95% CI: 0.96–2.49; p = 0.06). The seroprevalence of T. gondii infection was associated with suicide attempts in individuals aged 31–50 years (OR: 2.01; 95% CI: 1.09–3.71; p = 0.02), and with more than three suicide attempts (OR: 4.02; 95% CI: 1.34–12.03; p = 0.008). Our results indicate that T. gondii exposure is associated with suicidal behavior among patients attending primary care clinics.