Prenatal depression and anxiety in Toxoplasma gondii-positive women

Toxoplasma gondii infection and testosterone alteration: A systematic review and meta-analyses

BACKGROUND

Toxoplasma gondii (T. gondii) is a worldwide distributed protozoan parasite which has infected a wide range of warm-blooded animals and humans. The most common form of T. gondii infection is asymptomatic (latent); nevertheless, latent toxoplasmosis can induce various alterations of sex hormones, especially testosterone, in infected humans and animals. On the other hand, testosterone is involved in behavioral traits and reproductive functions in both sexes. Hence, the purpose of this systematic review is to summarize the available evidence regarding the association between T. gondii infection and testosterone alteration.

METHODS

In the setting of a systematic review, an electronic search (any date to 10 January 2023) without language restrictions was performed using Science Direct, Web of Science, PubMed, Scopus, and Google Scholar. The PRISMA guidelines were followed. Following the initial search, a total of 12,306 titles and abstracts were screened initially; 12,281 were excluded due to the lack of eligibility criteria or duplication. Finally, 24 articles met the included criteria. A mean±standard deviation (SD) was calculated to assess the difference of testosterone between T. gondii positive and T. gondii negative humans. The possibility of publication bias was assessed using Egger's regression. P-value < 0.05 was considered statistically significant.

RESULTS

This systematic review identified 24 articles (18 studies in humans and six studies in animals). Most human studies (13 out of 19) reported an increased level of testosterone following latent toxoplasmosis in males, while three studies reported decreased levels and two studies reported an insignificant change. Eleven articles (seven datasets in males and seven datasets in females) were eligible to be included in the data synthesis. Based on the random-effects model, the pooled mean± SD of testosterone in T. gondii positive than T. gondii negative was increased by 0.73 and 0.55 units in males and females, respectively. The Egger's regression did not detect a statistically significant publication bias in males and females (p = value = 0.95 and 0.71), respectively. Three studies in male animals (rats, mice, and spotted hyenas) and two studies in female animals (mice and spotted hyenas) reported a decline in testosterone in infected compared with non-infected animals. While, one study in female rats reported no significant changes of testosterone in infected than non-infected animals. Moreover, two studies in male rats reported an increased level of testosterone in infected than non-infected animals.

CONCLUSIONS

This study provides new insights about the association between T. gondii infection and testosterone alteration and identifies relevant data gaps that can inform and encourage further studies. The consequence of increased testosterone levels following T. gondii infection could partly be associated with increased sexual behavior and sexual transmission of the parasite. On the other hand, declining testosterone levels following T. gondii infection may be associated with male reproductive impairments, which were observed in T. gondii-infected humans and animals. Furthermore, these findings suggest the great need for more epidemiological and experimental investigations in depth to understand the relationship between T. gondii infection and testosterone alteration alongside with future consequences of testosterone alteration.

From the immune system to mood disorders especially induced by Toxoplasma gondii: CD4+ T cell as a bridge

Toxoplasma gondii (T. gondii), a ubiquitous and obligatory intracellular protozoa, not only alters peripheral immune status, but crosses the blood-brain barrier to trigger brain parenchymal injury and central neuroinflammation to establish latent cerebral infection in humans and other vertebrates. Recent findings underscore the strong correlation between alterations in the peripheral and central immune environment and mood disorders. Th17 and Th1 cells are important pro-inflammatory cells that can drive the pathology of mood disorders by promoting neuroinflammation. As opposed to Th17 and Th1, regulatory T cells have inhibitory inflammatory and neuroprotective functions that can ameliorate mood disorders. T. gondii induces neuroinflammation, which can be mediated by CD4+ T cells (such as Tregs, Th17, Th1, and Th2). Though the pathophysiology and treatment of mood disorder have been currently studied, emerging evidence points to unique role of CD4+ T cells in mood disorder, especially those caused by T. gondii infection. In this review, we explore some recent studies that extend our understanding of the relationship between mood disorders and T. gondii.

Use of in vitro derived human neuronal models to study host-parasite interactions of Toxoplasma gondii in neurons and neuropathogenesis of chronic toxoplasmosis

Toxoplasma gondii infects approximately one-third of the world's population resulting in a chronic infection with the parasite located in cysts in neurons in the brain. In most immunocompetent hosts the chronic infection is asymptomatic, but several studies have found correlations between Toxoplasma seropositivity and neuropsychiatric disorders, including Schizophrenia, and some other neurological disorders. Host-parasite interactions of bradyzoites in cysts in neurons is not well understood due in part to the lack of suitable in vitro human neuronal models. The advent of stem cell technologies in which human neurons can be derived in vitro from human induced pluripotent stem cells (hiPSCs) or direct conversion of somatic cells generating induced neurons (iNs), affords the opportunity to develop in vitro human neuronal culture systems to advance the understanding of T. gondii in human neurons. Human neurons derived from hiPSCs or iNs, generate pure human neuron monolayers that express differentiated neuronal characteristics. hiPSCs also generate 3D neuronal models that better recapitulate the cytoarchitecture of the human brain. In this review, an overview of iPSC-derived neurons and iN protocols leading to 2D human neuron cultures and hiPSC-derived 3D cerebral organoids will be given. The potential applications of these 2D and 3D human neuronal models to address questions about host-parasite interactions of T. gondii in neurons and the parasite in the CNS, will be discussed. These human neuronal in vitro models hold the promise to advance the understanding of T. gondii in human neurons and to improve the understanding of neuropathogenesis of chronic toxoplasmosis.

Quality of life, depressive symptoms, anxiety, and sexual function in mothers of neonates with congenital syphilis in the Northeast Brazil: A cohort study

Background

Congenital syphilis is an important public health problem in low- and middle-income countries. Poor neonatal health outcomes associated with the disease may lead to maternal psychological distress and feelings of helplessness. This study aimed to evaluate the quality of life, anxiety levels, depressive symptoms, and sexual function in mothers of neonates with congenital syphilis in the Northeast of Brazil.

Methods

This cohort study compared patient-centered outcomes between mothers of neonates with congenital syphilis and mothers of healthy neonates during the first three months of the postpartum period. The study was conducted in Sergipe state, Northeast Brazil, a region with one of the highest rates of congenital syphilis (14·1 cases per 1000 live births). Quality of life, depressive symptoms, anxiety levels, and sexual function were evaluated by using the World Health Organization Quality of Live - shortened version (WHOQoL-BREF) instrument, Beck Depression Inventory, Spielberger State-Trait Anxiety Inventory, and Female Sexual Function Index, respectively. Unadjusted differences between groups were anayzed by using the Mann-Whitney test. Glass's delta with 95% confidence interval (CI) was used to measure the effect size.

Findings

Sixty-three women were included in each group. During the in-hospital stay, mothers of neonates with congenital syphilis had lower scores for overall quality of life (p < 0·001; large effect size: -0·559 [95% CI -0·683 to -0·405]) and higher levels of anxiety (p < 0·001; large effect size: 0·558 [95% CI 0·403 to 0·681]) and depressive symptoms (p < 0·001; large effect size: 0·561 [95% CI 0·407 to 0·684]) than mothers of healthy neonates. Three months after childbirth, we found persistent depressive symptoms (p = 0·021; small effect size: 0·239 [95% CI 0·041 to 0·419]) and low overall sexual function (p = 0·041; small effect size: -0·211 [95% CI -0·394 to -0·012]) among mothers of neonates with congenital syphilis compared to the control group.

Interpretation

Mothers of neonates with congenital syphilis present poorer quality of life, mental health, and sexual function compared to mothers of healthy neonates.

Funding

Brazilian Federal Agency for Coordination of Improvement of Higher Education Personnel (CAPES).

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 of Toxoplasma gondii Seropositivity With Cognitive Function in Healthy People: A Systematic Review and Meta-analysis

IMPORTANCE

The parasite Toxoplasma gondii has been associated with behavioral alterations and psychiatric disorders. Studies investigating neurocognition in people with T gondii infection have reported varying results. To systematically analyze these findings, a meta-analysis evaluating cognitive function in healthy people with and without T gondii seropositivity is needed.

OBJECTIVE

To assess whether and to what extent T gondii seropositivity is associated with cognitive function in otherwise healthy people.

DATA SOURCES

A systematic search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. A systematic search of PubMed, MEDLINE, Web of Science, PsycInfo, and Embase was performed to identify studies from database inception to June 7, 2019, that analyzed cognitive function among healthy participants with available data on T gondii seropositivity. Search terms included toxoplasmosis, neurotoxoplasmosis, Toxoplasma gondii, cognition disorder, neuropsychological, and psychomotor performance.

STUDY SELECTION

Studies that performed cognitive assessment and analyzed T gondii seroprevalence among otherwise healthy participants were included.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently extracted data from published articles; if needed, authors were contacted to provide additional data. Quantitative syntheses were performed in predefined cognitive domains when 4 independent data sets per domain were available. Study quality, heterogeneity, and publication bias were assessed.

MAIN OUTCOMES AND MEASURES

Performance on neuropsychological tests measuring cognitive function.

RESULTS

The systematic search yielded 1954 records. After removal of 533 duplicates, an additional 1363 records were excluded based on a review of titles and abstracts. A total of 58 full-text articles were assessed for eligibility (including reference list screening); 45 articles were excluded because they lacked important data or did not meet study inclusion or reference list criteria. The remaining 13 studies comprising 13 289 healthy participants (mean [SD] age, 46.7 [16.0] years; 6586 men [49.6%]) with and without T gondii seropositivity were included in the meta-analysis. Participants without T gondii seropositivity had favorable functioning in 4 cognitive domains: processing speed (standardized mean difference [SMD], 0.12; 95% CI, 0.05-0.19; P = .001), working memory (SMD, 0.16; 95% CI, 0.06-0.26; P = .002), short-term verbal memory (SMD, 0.18; 95% CI, 0.09-0.27; P < .001), and executive functioning (SMD, 0.15; 95% CI, 0.01-0.28; P = .03). A meta-regression analysis found a significant association between older age and executive functioning (Q = 6.17; P = .01). Little suggestion of publication bias was detected.

CONCLUSIONS AND RELEVANCE

The study's findings suggested that T gondii seropositivity was associated with mild cognitive impairment in several cognitive domains. Although effect sizes were small, given the ubiquitous prevalence of this infection globally, the association with cognitive impairment could imply a considerable adverse effect at the population level. Further research is warranted to investigate the underlying mechanisms of this association.

Toxoplasma gondii seropositivity in patients with depressive and anxiety disorders

Introduction

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that is estimated to be carried by one-third of the world population. Latent T. gondii infection has been linked to several neuropsychiatric mood disorders and behaviors. The aim of the present study was to examine whether T. gondii seropositivity is associated with affective disorders, as well as with aggression reactivity and suicidal thoughts.

Methods

In the Netherlands Study of Depression and Anxiety (NESDA), T. gondii antibodies were assessed in patients with current depressive (n ​= ​133), anxiety (n ​= ​188), comorbid depressive and anxiety (n ​= ​148), and remitted disorders (n ​= ​889), as well as in healthy controls (n ​= ​373) based on DSM-IV criteria. Seropositivity was analyzed in relation to disorder status, aggression reactivity and suicidal thoughts using multivariate analyses of covariance and regression analyses.

Results

Participants were on average 51.2 years (SD ​= ​13.2), and 64.4% were female. Seropositivity was found in 673 participants (38.9%). A strong positive association between T. gondii seropositivity and age was observed. No significant associations were found between T. gondii seropositivity and disorder status, aggression reactivity and suicidal thoughts. The adjusted odds ratio (OR) for any remitted disorder versus controls was 1.13 (95% CI: 0.87-1.49), and for any current disorder versus controls was 0.94 (95% CI: 0.69-1.28).

Conclusions

No evidence was found for a relationship between affective disorders and T. gondii infection in the current sample.

Toxoplasmosis and Anxiety: A Review Study

Background: Toxoplasmosis, a significant zoonotic parasitic disease with serious health problems, is caused by apicomplexan protozoa, Toxoplasma gondii. Evidence has shown that Toxoplasma can also lead to psychological diseases. Objectives: The aim of this study was to collect information on the relationship between anxiety and toxoplasmosis. Materials and Methods: PubMed, Google Scholar, Noormags, and Magiran databases were searched for studies published from 2010 to October 2020. Studies that assessed the relationship between toxoplasmosis/toxoplasma and anxiety were included in the analysis. Synthesis of the results was the primary strategy for data analysis. Results: According to the inclusion and exclusion criteria, 16 articles were selected. They had been conducted in Iran, the USA, Turkey, the Czech Republic, Finland, Mexico, Austria, and Denmark. In general, the results of 8 out of 11 investigated human studies indicated that T. gondii infection was associated with anxiety. Moreover, five of them were non-human studies, and most of them showed that T. gondii caused anxiety-related symptoms. Conclusion: The results of most studies showed that toxoplasmosis could be associated with anxiety. However, more studies are needed to look closely at how anxiety relates to this parasite.

Relationship between Latent Toxoplasmosis and Depression in Clients of a Center for Assisted Reproduction

Latent infection of the globally spread parasite Toxoplasma gondii in humans has been associated with changes in personality and behavior. Numerous studies have investigated the effect of toxoplasmosis on depression, but their results are inconsistent. Our study focused on the effect of latent toxoplasmosis on depression in men and women in association with their fertility. In 2016-2018, we recruited clients (677 men and 664 women) of the Center for Assisted Reproduction and asked them to complete a standardized Beck Depression Inventory-II. In women without fertility problems, we found higher depression scores in Toxoplasma-positive than in Toxoplasma-negative (p = 0.010, Cohen's d = 0.48). Toxoplasma-positive infertile men, on the other hand, had lower depression scores than Toxoplasma-negative infertile men (p ≤ 0.001, Cohen's d = 0.48). Our results are consistent with the previously described effects of latent toxoplasmosis, which seem to go in opposite directions regarding the effect on personality and behavior of men and women. Our results could be explained by gender-contrasting reactions to chronic stress associated with lifelong infection. This suggests that due to gender differences in the impact of latent toxoplasmosis, future studies ought to perform separate analyses for women and men.

Toxoplasma gondii induces metabolic disturbances in the hippocampus of BALB/c mice

Toxoplasma gondii can cross the blood-brain barrier and infect different regions of the brain including the hippocampus. In the present study, we examined the impact of Toxoplasma gondii infection on the metabolism of the hippocampus of female BALB/c mice compared to control mice using ultra-high-performance liquid chromatography-tandem mass spectrometry. Multivariate analysis revealed significant differences between infected and control hippocampi and identified 25, 82, and 105 differential metabolites (DMs) in the infected hippocampi at 7, 14, and 21 days post-infection (dpi), respectively. One DM (sphingosyl-phosphocholine in the sphingolipid metabolism pathway) and 11 dysregulated pathways were detected at all time points post-infection, suggesting their important roles in the neuropathogenesis of T. gondii infection. These pathways were related to neural activity, such as inflammatory mediator regulation of TRP channels, retrograde endocannabinoid signaling, and arachidonic acid metabolism. Weighted correlation network analysis and receiver operating characteristic analysis identified 33 metabolites significantly associated with T. gondii infection in the hippocampus, and 30 of these were deemed as potential biomarkers for T. gondii infection. This study provides, for the first time, a global view of the metabolic perturbations that occur in the mouse hippocampus during T. gondii infection. The potential relevance of the identified metabolites and pathways to the pathogenesis of cognitive impairment and psychiatric disorders are discussed.

Correlation of Suicidal Thoughts and Toxoplasmosis in Patients With Depression

Objective

We investigated the correlation between serum anti-Toxplasma gondii IgG and suicidal thoughts in depressive patients.

Methods

Depressive patients with (n = 100) and without (n = 100) suicidal thoughts along with 100 healthy control subjects were recruited for this study. In all three groups, a semi-structured clinical interview form called Structured Clinical Interview for DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) Axis-I Disorder (SCID-I), Hamilton Depression Rating Scale (HAMD), suicidal behavior scale, and a sociodemographic data form were completed. Sera from all participants were taken, and anti-toxoplasma IgG was measured by Enzyme Linked Immunosorbent Assay (ELISA)-Chemiluminescent Microparticle Immunoassay. Statistical analysis of the data was performed.

Results

The serum anti-toxoplasma IgG levels of patients with suicidal thoughts were significantly higher than those without suicidal thoughts and the controls, which were 80.04 ± 40.66, 78 ± 14.82, and 19.98 ± 14.65, respectively, p < 0.001. There was no correlation between toxoplasma IgG and HAMD score in patients lacking suicidal thoughts (r = -0.112, p = 0.463).

Conclusion

This study shows a correlation between seropositivity for anti-Toxoplasma gondii IgG and depression with suicidal thoughts.

Toxoplasma gondii, Suicidal Behavior, and Intermediate Phenotypes for Suicidal Behavior

Within the general literature on infections and suicidal behavior, studies on Toxoplasma gondii (T. gondii) occupy a central position. This is related to the parasite's neurotropism, high prevalence of chronic infection, as well as specific and non-specific behavioral alterations in rodents that lead to increased risk taking, which are recapitulated in humans by T. gondii's associations with suicidal behavior, as well as trait impulsivity and aggression, mental illness and traffic accidents. This paper is a detailed review of the associations between T. gondii serology and suicidal behavior, a field of study that started 15 years ago with our publication of associations between T. gondii IgG serology and suicidal behavior in persons with mood disorders. This "legacy" article presents, chronologically, our primary studies in individuals with mood disorders and schizophrenia in Germany, recent attempters in Sweden, and in a large cohort of mothers in Denmark. Then, it reviews findings from all three meta-analyses published to date, confirming our reported associations and overall consistent in effect size [ranging between 39 and 57% elevation of odds of suicide attempt in T. gondii immunoglobulin (IgG) positives]. Finally, the article introduces certain links between T. gondii and biomarkers previously associated with suicidal behavior (kynurenines, phenylalanine/tyrosine), intermediate phenotypes of suicidal behavior (impulsivity, aggression) and state-dependent suicide risk factors (hopelessness/dysphoria, sleep impairment). In sum, an abundance of evidence supports a positive link between suicide attempts (but not suicidal ideation) and T. gondii IgG (but not IgM) seropositivity and serointensity. Trait impulsivity and aggression, endophenotypes of suicidal behavior have also been positively associated with T. gondii seropositivity in both the psychiatrically healthy as well as in patients with Intermittent Explosive Disorder. Yet, causality has not been demonstrated. Thus, randomized interventional studies are necessary to advance causal inferences and, if causality is confirmed, to provide hope that an etiological treatment for a distinct subgroup of individuals at an increased risk for suicide could emerge.

Infection with Toxoplasma gondii increases the risk of psychiatric disorders in Taiwan: a nationwide population-based cohort study

This study aimed to evaluate associations between toxoplasmosis and psychiatric disorders in Taiwan based on the National Health Insurance Research Database, Taiwan (1997-2013). Patients newly diagnosed with toxoplasmosis formed the case group (n = 259), and the control group included propensity-score matched patients without toxoplasmosis (n = 1036). The primary outcome was incidence of psychiatric disorders. Cox proportional hazards regression and stratified analyses were performed to examine risk of developing specific psychiatric disorders between patients with and without toxoplasmosis. Patients with toxoplasmosis had significantly higher incidence of psychiatric disorders than those without toxoplasmosis (P = 0.016). A significant difference was found in numbers of psychiatric disorders between the two groups during 14 years of follow-up (log-rank P < 0.001). Those with toxoplasmosis had significantly higher risk of bipolar disorder [adjusted hazard ratio (aHR = 3.60, 95% confidence interval (CI) = 2.07, 7.26), depression (aHR = 4.94, 95% CI = 2.15, 11.80) and anxiety (aHR = 5.36, 95% CI = 2.98, 25.88), but no significant between-group differences were found for schizophrenia and other psychiatric disorders. In conclusion, the present nationwide population-based analysis revealed that Toxoplasma gondii infection in Taiwan significantly increases the risk for developing bipolar disorder, depression and anxiety, but not for schizophrenia and other psychiatric disorders.

Relationship of Anxiety, Inflammation, and Telomere Length in Postpartum Women: A Pilot Study

BACKGROUND

The postpartum period can be a vulnerable time during which many women are prone to mood disturbances. Since telomere length (TL) is known to be associated with dysphoric moods, inflammation, and stress in many populations, this study's objective was to assess the relationships among TL, dysphoric moods, stress, and inflammation during the postpartum period.

METHOD

This cross-sectional pilot study is a secondary analysis of data collected in a larger parent study of anti-thyroid peroxidase (TPO) enzyme antibody positive versus negative women. The parent study followed selected mothers every month for 6 postpartum months. From this parent study, a random sample of preserved peripheral blood mononuclear cells from 97 participants collected at 2-4 months postpartum were measured for TL. Data were available on the production of interleukin-6 (IL-6), an inflammatory cytokine, in stimulated ex vivo cultures for 59 of these women. Dysphoric moods and stress were measured. Pearson correlations and linear regressions were performed, controlling for postpartum thyroiditis status and age.

RESULTS

There were no statistically significant relationships between TL and demographic factors, stress, depression, or TPO status. There were significant negative correlations between TL and anxiety and a trend for a relationship between TL and IL-6 levels. IL-6 levels were significantly, positively associated with negative moods.

CONCLUSIONS

Higher anxiety scores and inflammation were associated with shorter TL. Inflammation was related to anxiety and other dysphoric moods and was marginally associated with shorter TLs.

A systematic review of the impact of psychosocial factors on immunity: Implications for enhancing BCG response against tuberculosis

BACKGROUND

Tuberculosis (TB) remains an urgent global public health priority, causing 1.5 million deaths worldwide in 2018. There is evidence that psychosocial factors modulate immune function; however, how this may influence TB risk or BCG vaccine response, and whether this pathway can be modified through social protection, has not been investigated. This paper aims to: a) systematically review evidence of how psychosocial factors influence the expression of biomarkers of immunity, and b) apply this general evidence to propose plausible TB-specific pathways for future study.

METHODS

Papers reporting on the impact of psychosocial stressors on immune biomarkers in relation to infectious disease risk were identified through a search of the databases MEDLINE, PsycINFO, Global Health and PsycEXTRA alongside reference list and citation searching of key papers. Data extraction and critical appraisal were carried out using a standardised form. The findings were tabulated and synthesised narratively by infectious disease category, and used to propose plausible mechanisms for how psychosocial exposures might influence immune outcomes relevant to TB and BCG response.

RESULTS

27,026 citations were identified, of which 51 met the inclusion criteria. The literature provides evidence of a relationship between psychosocial factors and immune biomarkers. While the direction and strength of associations is heterogenous, some overarching patterns emerged: adverse psychosocial factors (e.g. stress) were generally associated with compromised vaccine response and higher antibody titres to herpesviruses, and vice versa for positive psychosocial factors (e.g. social support).

CONCLUSIONS

The evidence identifies pathways linking psychosocial factors and immune response: co-viral infection and immune suppression, both of which are potentially relevant to TB and BCG response. However, the heterogeneity in the strength and nature of the impact of psychosocial factors on immune function, and lack of research on the implications of this relationship for TB, underscore the need for TB-specific research.

Metabolic modulation of redox state confounds fish survival against Vibrio alginolyticus infection

Vibrio alginolyticus threatens both humans and marine animals, but hosts respond to V. alginolyticus infection is not fully understood. Here, functional metabolomics was adopted to investigate the metabolic differences between the dying and surviving zebrafish upon V. alginolyticus infection. Tryptophan was identified as the most crucial metabolite, whose abundance was decreased in the dying group but increased in the survival group as compared to control group without infection. Concurrently, the dying zebrafish displayed excessive immune response and produced higher level of reactive oxygen species (ROS). Interestingly, exogenous tryptophan reverted dying rate through metabolome re‐programming, thereby enhancing the survival from V. alginolyticus infection. It is preceded by the following mechanism: tryptophan fluxed into the glycolysis and tricarboxylic acid cycle (TCA cycle), promoted adenosine triphosphate (ATP) production and further increased the generation of NADPH. Meanwhile, tryptophan decreased NADPH oxidation. These together ameliorate ROS, key molecules in excessive immune response. This is further supported by the event that the inhibition of pyruvate metabolism and TCA cycle by inhibitors decreased D. reiro survival. Thus, our data indicate that tryptophan is a key metabolite for the host to fight against V. alginolyticus infection, representing an alternative strategy to treat bacterial infection in an antibiotic‐independent way.

Global prevalence of latent toxoplasmosis in pregnant women: a systematic review and meta-analysis

BACKGROUND

Toxoplasma gondii infection, if acquired as an acute infection during pregnancy, can have substantial adverse effects on mothers, fetuses and newborns. Latent toxoplasmosis also causes a variety of pathologies and has been linked to adverse effects on pregnancy.

OBJECTIVE

Here, we present results of a comprehensive systematic review and meta-analysis of the global prevalence of latent toxoplasmosis in pregnant women.

DATA SOURCE

We searched PubMed, EMBASE, Web of Science, SciELO and Scopus databases for relevant studies that were published between 1 January 1988 and 20 July 2019.

STUDY ELIGIBILITY CRITERIA

All population-based, cross-sectional and longitudinal studies reporting the prevalence of latent toxoplasmosis in healthy pregnant women were considered for inclusion.

PARTICIPANTS

Pregnant women who were tested for prevalence of latent toxoplasmosis.

INTERVENTIONS

There were no interventions.

METHOD

We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CIs). We grouped prevalence data according to the geographic regions defined by the World Health Organization (WHO). Multiple subgroup and meta-regression analyses were performed.

RESULTS

In total, 311 studies with 320 relevant data sets representing 1 148 677 pregnant women from 91 countries were eligible for inclusion in the meta-analysis. The global prevalence of latent toxoplasmosis in pregnant women was estimated at 33.8% (95% CI, 31.8-35.9%; 345 870/1 148 677). South America had the highest pooled prevalence (56.2%; 50.5-62.8%) of latent toxoplasmosis in pregnant women, whereas the Western Pacific region had the lowest prevalence (11.8%; 8.1-16.0%). A significantly higher prevalence of latent toxoplasmosis was associated with countries with low income and low human development indices (p < 0.001).

CONCLUSION

Our results indicate a high level of latent toxoplasmosis in pregnant women, especially in some low- and middle-income countries of Africa and South America, although the local prevalence varied markedly. These results suggest a need for improved prevention and control efforts to reduce the health risks to women and newborns.

Association of Suicide Attempt With Seroprevalence of Toxoplasma gondii in Adolescents

In this study, we aimed to explore the potential pathophysiological relationship between suicide attempts and Toxoplasma gondii infection. Fifty patients aged between 12 and 18 years who attempted suicide and 50 healthy adolescents were included in this study. All adolescents were evaluated by a child psychiatrist using a semistructured interview and Rosenberg Self-Esteem Scale (RSES), Children's Depression Inventory (CDI), and Inventory of Parent and Peer Attachment. T. gondii IgM and IgG antibodies of patients and control subjects were analyzed from blood samples by enzyme-linked immunosorbent assay. Psychiatric disorders particularly mood disorders were more common in adolescents in the patient group. Adolescents attempting suicide were found to have worse relationships with their parents; their CDI scores were higher, and their RSES scores were lower than their healthy peers. There were no significant differences between the patient and the control groups in terms of Toxoplasma IgG antibody positivity. Although the seropositivity of Toxoplasma IgG antibody was higher in the patient group than that in the control group, the difference between the two groups was not statistically significant.

Toxoplasma gondii Serointensity and Seropositivity: Heritability and Household-Related Associations in the Old Order Amish

Toxoplasma gondii (T. gondii) is an intracellular parasite infecting one third of the world's population. Latent T. gondii infection has been associated with mental illness, including schizophrenia and suicidal behavior. T. gondii IgG antibody titers were measured via ELISA. The heritability of T. gondii IgG was estimated using a mixed model that included fixed effects for age and sex and random kinship effect. Of 2017 Old Order Amish participants, 1098 had positive titers (54.4%). The heritability for T. gondii serointensity was estimated to be 0.22 (p = 1.7 × 10-8 and for seropositivity, it was estimated to be 0.28 (p = 1.9 × 10-5). Shared household environmental effects (i.e., household effects) were also determined. Household effects, modeled as a random variable, were assessed as the phenotypic covariance between any two individuals who had the same current address (i.e., contemporaneous household), and nuclear household (i.e., the phenotypic covariance between parents and children only, not other siblings or spouses). Household effects did not account for a significant proportion of variance in either T. gondii serointensity or T. gondii seropositivity. Our results suggest a significant familial aggregation of T. gondii serointensity and seropositivity with significant heritability. The shared household does not contribute significantly to family aggregation with T. gondii, suggesting that there are possible unmeasured non-household shared and non-shared environmental factors that may play a significant role. Furthermore, the small but significant heritability effects justify the exploration of genetic vulnerability to T. gondii exposure, infection, virulence, and neurotropism.

Persistent Toxoplasma Infection of the Brain Induced Neurodegeneration Associated with Activation of Complement and Microglia

Toxoplasma gondii, a common neurotropic parasite, is increasingly being linked to neuropsychiatric disorders, including schizophrenia, Alzheimer's disease, and Parkinson's disease. However, the pathogenic mechanisms underlying these associations are not clear. Toxoplasma can reside in the brain for extensive periods in the form of tissue cysts, and this process requires a continuous immune response to prevent the parasite's reactivation. Because neuroinflammation may promote the onset and progression of neurodegenerative diseases, we investigated neurodegeneration-associated pathological changes in a mouse model of chronic Toxoplasma infection. Under conditions of high-grade chronic infection, we documented the presence of neurodegeneration in specific regions of the prefrontal cortex, namely, the anterior cingulate cortex (ACC) and somatomotor cortex (SC). Neurodegeneration occurred in both glutamatergic and GABAergic neurons. Neurons that showed signs of degeneration expressed high levels of CX3CL1, were marked by profoundly upregulated complement proteins (e.g., C1q and C3), and were surrounded by activated microglia. Our findings suggest that chronic Toxoplasma infection leads to cortical neurodegeneration and results in CX3CL1, complement, and microglial interactions, which are known to mediate the phagocytic clearance of degenerating neurons. Our study provides a mechanistic explanation for the link between Toxoplasma infection and psychiatric disorders.

Driving us mad: the association of Toxoplasma gondii with suicide attempts and traffic accidents - a systematic review and meta-analysis

Unnatural causes of death due to traffic accidents (TA) and suicide attempts (SA) constitute a major burden on global health, which remained stable in the last decade despite widespread efforts of prevention. Recently, latent infection with Toxoplasma gondii (T. gondii) has been suggested to be a biological risk factor for both TA and SA. Therefore, a systematic search concerning the relationship of T. gondii infection with TA and/or SA according to PRISMA guidelines in Medline, Pubmed and PsychInfo was conducted collecting papers up to 11 February 2019 (PROSPERO #CRD42018090206). The random-effect model was applied and sensitivity analyses were subsequently performed. Lastly, the population attributable fraction (PAF) was calculated. We found a significant association for antibodies against T. gondii with TA [odds ratio (OR) = 1.69; 95% confidence interval (CI) 1.20-2.38, p = 0.003] and SA (OR = 1.39; 95% CI 1.10-1.76, p = 0006). Indication of publication bias was found for TA, but statistical adjustment for this bias did not change the OR. Heterogeneity between studies on SA was partly explained by type of control population used (ORhealthy controls = 1.9, p &lt; 0.001 v. ORpsychiatric controls = 1.06, p = 0.87) and whether subjects with schizophrenia only were analysed (ORschizophrenia = 0.87, p = 0.62 v. ORvarious = 1.8, p &lt; 0.001). The association was significantly stronger with higher antibody titres in TA and in studies that did not focus on schizophrenia subjects concerning SA. PAF of a T. gondii infection was 17% for TA and 10% for SA. This indicates that preventing T. gondii infection may play a role in the prevention of TA or SA, although uncertainty remains whether infection and outcome are truly causally related.

Is there any association between Toxoplasma gondii infection and depression? A systematic review and meta-analysis

BACKGROUND

Toxoplasma gondii (T. gondii) is an obligate intracellular opportunistic parasite that is the causative agent of toxoplasmosis. This parasite accounts for mental disorders; however, the relationship between T. gondii infection and depressive disorder is unclear. Regarding this, the present systematic review and meta-analysis was conducted to investigate the scientific evidence regarding the potential association between major depression disorder (MDD) and Toxoplasma infection.

METHODS

For the purpose of the study, the articles related to the subject of interest were systematically searched in seven electronic databases. Special attention was given to the studies examining T. gondii seropositivity level in depressed patients and controls.

RESULTS

The search process resulted in the identification of a total of 30 publications meeting the inclusion criteria and published up to April 2018 for the systematic review. Furthermore, 29 studies met the inclusion criteria to be entered into meta-analysis. Our meta-analysis involved the review of cross-sectional studies including 1657 depressed patients and 19565 individuals as controls and case-control studies entailing 1311 depressed cases and 6015 controls without depression. 1582 depressed people participated in cross-sectional studies whose results were reported as odds ratio (OR). In addition, the total number of participants was 15068 in this type of studies. Statistical analysis indicated that the pooled OR of the risk of anti-T. gondii IgG antibody in depressed individuals in case-control and cross-sectional studies was 1.15 (95% confidence interval (CI): 0.95-1.39).

CONCLUSIONS

As the findings of the reviewed articles indicated, toxoplasmosis is not a risk factor for MDD. However, it is necessary to perform further research to clarify the detailed association between T. gondii and dysthymia or mild and moderate depression. Furthermore, it is recommended to better investigate the effect of antibody titers on the relationship between depression and T. gondii infection.

The association between Toxoplasma gondii infection and postpartum blues

INTRODUCTION AND AIM

Toxoplasma gondii is an intracellular protozoan parasite infecting approximately 30% of the global human population. It has often been suggested that chronic infection with T. gondii is related to personality changes and various mental disorders including depression. It is not known whether this includes post-partum blues or depression. In this study, we test the hypothesis that there is a relationship between T. gondii infection and post-partum blues by measuring the association between infection and postpartum blues.

METHODS

A total of 475 Chinese women who have just given birth were detected serology for Toxoplasma IgG and IgM antibodies, and evaluated the degree of depression by Hamilton Depression Scale (HAMD) score. Data were analyzed by Chi-square or Fisher's Exact tests using SPSS software.

RESULTS

We found an overall Toxoplasma seroprevalence of 5.68% (27/475; 95% CI: 3.59-7.77) which was broken down into a prevalence of 6.60% (7/106; 95% CI: 1.80-11.41) in mothers with post-partum blues and 5.42% (20/369; 95% CI: 3.10-7.74) in non-affected mothers. There was no significant association between infection and post-partum blues (p = 0.64).

CONCLUSION

The results suggest that there is no relationship between T. gondii infection and postpartum blues, at least in this sample of patients from China.

A Longitudinal Study of the Association Between Persistent Pathogens and Incident Depression Among Older U.S. Latinos

Depression is estimated to affect more than 6.5 million Americans 65 years of age and older and compared with non-Latino whites older U.S. Latinos have a greater incidence and severity of depression, warranting further investigation of novel risk factors for depression onset among this population. We used data on 771/1,789 individuals ≥60 years of age from the Sacramento Area Latino Study on Aging (1998-2008) who were tested for cytomegalovirus (CMV), herpes simplex virus, varicella zoster, Helicobacter pylori, Toxoplasma gondii, and C-reactive protein (CRP) and interleukin-6 (IL-6) level. Among those without elevated depressive symptoms at baseline, we examined the association between each pathogen, inflammatory markers and incident depression over up to nearly 10 years of follow-up using discrete-time logistic regression. We found that only CMV seropositivity was statistically significantly associated with increased odds of incident depression (odds ratio [OR]: 1.38, 95% confidence interval [CI]: 1.00-1.90) in the total sample as well as among women only (OR: 1.70, 95% CI: 1.01-2.86). These associations were not mediated by CRP or IL-6 levels. Our findings suggest that CMV seropositivity may serve as an important risk factor for the onset of depression among older U.S. Latinos, but act outside of inflammatory pathways.

Latent toxoplasmosis and psychiatric symptoms - A role of tryptophan metabolism?

Toxoplasma gondii (TOX) is a common parasite which infects approximately one third of the human population. In recent years, it has been suggested that latent toxoplasmosis may be a risk factor for the development of mental disorders, particularly schizophrenia and anxiety. With regards to depression the results have been varied. The main objective of this study was to examine subpopulations from the Danish PRISME and GENDEP populations for TOX IgG antibodies. These consisted of: a group with symptoms of anxiety, a group suffering from burnout syndrome, as well as two different subpopulations with depression of differing severity. The secondary objective of this study was to examine whether tryptophan metabolism was altered in TOX-positive subjects within each subpopulation. Our results show that the anxiety and burnout populations were more likely to be TOX IgG seropositive. Furthermore, we find that the moderate-severe but not mild-moderate depressive subpopulation were associated with TOX seropositivety, suggesting a possible role of symptom severity. Additionally, we found that TOX positive subjects in the anxiety and burnout subpopulations had altered tryptophan metabolism. This relationship did not exist in the mild-moderate depressive subpopulation. These results suggest that TOX seropositivity may be related to anxiety, burnout and potentially to severity of depression. We furthermore show that the psychiatric symptoms could be associated with an altered tryptophan metabolism.

Latent toxoplasmosis aggravates anxiety- and depressive-like behaviour and suggest a role of gene-environment interactions in the behavioural response to the parasite

Toxoplasma gondii (TOX) is an intracellular parasite which infects warm-blooded animals including humans. An increasing number of clinical studies now hypothesize that latent toxoplasmosis may be a risk factor for the development of psychiatric disease. For depression, the results have been varied and we speculate that genetic background is important for the response to latent toxoplasmosis. The main objective of this study was to elucidate gene - environment interactions in the behavioural response to TOX infection by use of genetically vulnerable animals (Flinders sensitive line, FSL) compared to control animals (Flinders resistant line, FRL). Our results show that all infected animals displayed increased anxiety-like behaviour whereas only genetically vulnerable animals (FSL rats) showed depressive-like behaviour as a consequence of the TOX infection. Furthermore, peripheral cytokine expression was increased following the infection, primarily independent of strain. In the given study 14 cytokines, chemokines, metabolic hormones, and growth factors were quantified with the bead-based Luminex200 system, however, only IL-1α expression was affected differently in FSL animals compared to FRL rats. These results suggest that latent TOX infection can induce anxiety-like behaviour independent of genetic background. Intriguingly, we also report that for depressive-like behaviour only the vulnerable rat strain is affected. This could explain the discrepancy in the literature as to whether TOX infection is a risk factor for depressive symptomatology. We propose that the low grade inflammation caused by the chronic infection is related to the development of behavioural symptoms.

Toxoplasma gondii: Biological Parameters of the Connection to Schizophrenia

It is increasingly evident that the brain is not truly an immune privileged site and that cells of the central nervous system are sensitive to the inflammation generated when the brain is fighting off infection. Among the many microorganisms that have access to the brain, the apicomplexan protozoan Toxoplasma gondii has been one of the most studied. This parasite has been associated with many neuropsychiatric disorders including schizophrenia. This article provides a comprehensive review of the status of Toxoplasma research in schizophrenia. Areas of interest include (1) the limitations and improvements of immune-based assays to detect these infections in humans, (2) recent discoveries concerning the schizophrenia-Toxoplasma association, (3) findings of Toxoplasma neuropathology in animal models related to schizophrenia pathogenesis, (4) interactions of Toxoplasma with the host genome, (5) gastrointestinal effects of Toxoplasma infections, and (6) therapeutic intervention of Toxoplasma infections.

An updated literature review on maternal-fetal and reproductive disorders of Toxoplasma gondii infection

BACKGROUND

Toxoplasma gondii infection is one of the most prevalent infectious disease with worldwide distribution. Congenital toxoplasmosis is annually responsible for 1.20 million disability-adjusted life years around the world, but often it is overlooked many countries.

METHODS

We performed an updated review to summarize the current researches on fetal, neonatal and maternal consequences of T. gondii infection and also adverse effects of toxoplasmosis on women reproductive organs.

RESULTS

T. gondii infection could be cause of several abnormalities from hydrocephalus, microcephaly, deafness, abortion and still birth in fetal to psychomotor retardation, intellectual disability, hearing loss, slower postnatal motor development during the first year of life; and chorioretinitis, cryptogenic epilepsy and autism spectrum disorders in newborns. Moreover, this infection is related with neuropsychiatric disorders such as anxiety, schizophrenia spectrum disorders, depression, decreased weight, autoimmune thyroid diseases, self-directed violence, violent suicide attempts in mothers. This literature review emphasized that toxoplasmosis could be an important neglected factor endometritis, ovarian dysfunction, impaired folliculogenesis, ovarian and uterine atrophy, decrease in reproductive organs weight and reproductive performance in women. We reviewed role of the immunological profile such as pro-infiammatory cytokines and hormonal changes as main potential mechanisms related to this infection and development of maternal-fetal and reproductive disorders.

CONCLUSION

T. gondii is associated with several brain related disorders in both mothers and newborns, and also it is cause of several abnormalities in reproductive organs. Early diagnosis and treatment of the infection could be effective to significantly improve the clinical outcome.

Toxoplasma gondii infection and common mental disorders in the Finnish general population

OBJECTIVE

We investigated whether T. gondii seropositivity is associated with 12-month depressive, anxiety and alcohol use disorders and current depressive symptoms and whether inflammation, measured by C-reactive protein (CRP) level, explains these associations.

METHOD

Health 2000 study (BRIF8901), conducted in years 2000-2001, is based on a nationally representative sample of Finns aged 30 and above, with 7112 participants and 88.6% response rate. DSM-IV depressive, anxiety and alcohol use disorders were assessed with the Composite International Diagnostic Interview and depressive symptoms with the Beck Depressive Inventory (BDI-21). We used logistic regression to investigate the association of T. gondii seropositivity with mental disorders and linear regression with BDI-21 scores.

RESULTS

T. gondii seroprevalence was significantly associated with 12-month generalized anxiety disorder but not with other anxiety, depressive or alcohol use disorders. T. gondii seropositivity was associated with higher BDI-21 scores (beta 0.56, 95% CI 0.12-1.00, P = 0.013) and with having a comorbid depressive and anxiety disorder (OR 1.86, 95% CI 1.16-2.97, P = 0.010). Higher CRP levels were associated with these outcomes and with T. gondii seropositivity, but adjusting for CRP did not change the effect of T. gondii seropositivity.

LIMITATIONS

Cross-sectional study design with no information on the timing of T. gondii infection.

CONCLUSION

T. gondii seropositivity is associated with generalized anxiety disorder, depressive symptoms and comorbid depressive and anxiety disorders, which is not mediated by inflammation.

Positive association between Toxoplasma gondii IgG serointensity and current dysphoria/hopelessness scores in the Old Order Amish: a preliminary study

Toxoplasma gondii (T. gondii) IgG seropositivity and serointensity have been previously associated with suicidal self-directed violence (SSDV). Although associations with unipolar depression have also been investigated, the results have been inconsistent, possibly as a consequence of high heterogeneity. We have now studied this association in a more homogeneous population, [that is (i.e.) Old Order Amish (OOA)] with previously reported high T. gondii seroprevalence. In 306 OOA with a mean age of 46.1 ± 16.7 years, including 191 (62.4%) women in the Amish Wellness Study, we obtained both T. gondii IgG titers (by enzyme-linked immunosorbent assay [ELISA]), and depression screening questionnaires (Patient Health Questionnaire [PHQ-9] [n = 280] and PHQ-2 [n = 26]). Associations between T. gondii IgG and dysphoria/hopelessness and anhedonia scores on depression screening questionnaires were analyzed using multivariable linear methods with adjustment for age and sex. Serointensity was associated with both current dysphoria/hopelessness (p = 0.045) and current combined anhedonia and dysphoria/hopelessness (p = 0.043), while associations with simple anhedonia and past/lifelong (rather than current) phenotypes were not significant. These results indicate the need for larger longitudinal studies to corroborate the association between dysphoria/hopelessness and T. gondii IgG-titers. Current hopelessness is a known risk factor for SSDV which responds particularly well to cognitive behavioral therapy, and may be a focused treatment target for T. gondii-positive individuals at high-risk for SSDV.

Use of Human Neurons Derived via Cellular Reprogramming Methods to Study Host-Parasite Interactions of Toxoplasma gondii in Neurons

Toxoplasma gondii is an intracellular protozoan parasite, with approximately one-third of the worlds' population chronically infected. In chronically infected individuals, the parasite resides in tissue cysts in neurons in the brain. The chronic infection in immunocompetant individuals has traditionally been considered to be asymptomatic, but increasing evidence indicates that chronic infection is associated with diverse neurological disorders such as schizophrenia, cryptogenic epilepsy, and Parkinson's Disease. The mechanisms by which the parasite exerts affects on behavior and other neuronal functions are not understood. Human neurons derived from cellular reprogramming methods offer the opportunity to develop better human neuronal models to study T. gondii in neurons. Results from two studies using human neurons derived via cellular reprogramming methods indicate these human neuronal models provide better in vitro models to study the effects of T. gondii on neurons and neurological functions. In this review, an overview of the current neural reprogramming methods will be given, followed by a summary of the studies using human induced pluripotent stem cell (hiPSC)-derived neurons and induced neurons (iNs) to study T. gondii in neurons. The potential of these neural reprogramming methods for further study of the host-parasite interactions of T. gondii in neurons will be discussed.

Association between Toxoplasma gondii seropositivity and memory function in nondemented older adults

Toxoplasma gondii (T. gondii) seropositivity may be associated with decreased memory in older adults. To further investigate the association between T. gondii seropositivity and memory in nondemented older adults, we obtained serum samples from 114 nondemented older adults evaluated by the Alzheimer's Disease and Research Center at Washington University in St. Louis, Missouri, USA. We determined T. gondii seropositivity and anti-T. gondii IgG antibody titer and examined associations with memory function while controlling for socioeconomic status, education level, age, and apolipoprotein E4 status. There were few associations between T. gondii seropositivity or anti-T. gondii IgG antibodies and memory, although there was some support suggesting an interaction between anti-T. gondii and sex. In the seropositive-only sample, there was an inverse relationship between anti-T. gondii titer and performance on the selective reminding test. Overall, we found little evidence of an association between impaired memory function and T. gondii seropositivity and anti-T. gondii IgG antibodies in this sample of nondemented older adults.

Prenatal toxoplasmosis antibody and childhood autism

There is evidence that some maternal infections during the prenatal period are associated with neurodevelopmental disorders, such as childhood autism. However, the association between autism and Toxoplasma gondii (T. gondii), an intracellular parasite, remains unclear. The authors examined whether serologically confirmed maternal antibodies to T. gondii are associated with odds of childhood autism in offspring. The study is based on a nested case-control design of a large national birth cohort (N = 1.2 million) and the national psychiatric registries in Finland. There were 874 cases of childhood autism and controls matched 1:1 on date of birth, sex, birthplace and residence in Finland. Maternal sera were prospectively assayed from a national biobank for T. gondii IgM and IgG antibodies; IgG avidity analyses were also performed. High maternal T. gondii IgM antibody was associated with a significantly decreased odds of childhood autism. Low maternal T. gondii IgG antibody was associated with increased offspring odds of autism. In women with high T. gondii IgM antibodies, the IgG avidity was high for both cases and controls, with the exception of three controls. The findings suggest that the relationship between maternal T. gondii antibodies and odds of childhood autism may be related to the immune response to this pathogen or the overall activation of the immune system. Autism Res 2017, 10: 769-777. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Lack of association between Toxoplasma gondii exposure and depression in pregnant women: a case-control study

Background

Very little is known about the link of T. gondii infection and depression. Through an age-, gender-, and month of pregnancy-matched case-control study, we determined the association of T. gondii infection and depression in pregnant women.

Methods

We studied 200 pregnant women with depression and 200 pregnant women without depression attended in a public hospital in Durango City, Mexico. Pregnant women were tested for the presence of anti-Toxoplasma IgG antibodies using an enzyme-linked immunoassay (EIA), and IgG seropositive women were further tested for the presence of IgM using an EIA. IgM positivity by EIA was further analyzed by enzyme-linked fluorescence assay (ELFA).

Results

Anti-T. gondii IgG antibodies were found in 9 (4.5%) of the 200 cases and in 12 (6.0%) of the 200 controls (OR = 0.73; 95% CI: 0.30–1.79; P = 0.50). The frequency of high (>150 IU/ml) anti-T. gondii IgG levels was similar in cases and in controls (OR = 1.20; 95% CI: 0.36–4.01; P = 0.75). Two women were positive for IgM by EIA but both were negative by ELFA.

Conclusions

We did not find serological evidence of an association between T. gondii infection and depression in pregnant women attended in a public hospital in Durango City, Mexico. Since an association of T. gondii and depression in pregnancy has been reported in the U.S. previously, further research to elucidate the role of T. gondii in prenatal depression should be conducted.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2292-1) contains supplementary material, which is available to authorized users.

Toxoplasma gondii exposure and Parkinson's disease: a case-control study

OBJECTIVES

To determine the association between Toxoplasma gondii infection and Parkinson's disease and to investigate whether T. gondii seropositivity is associated with the general characteristics of patients with Parkinson's disease.

DESIGN

Case-control study.

SETTING

Cases and controls were enrolled in Durango City, Mexico.

PARTICIPANTS

65 patients with Parkinson's disease and 195 age- and gender-matched control subjects without Parkinson's disease.

PRIMARY AND SECONDARY OUTCOME MEASURES

Serum samples of participants were analysed for anti-T. gondii IgG and IgM antibodies by commercially available enzyme-linked immunoassays. Prevalence of T. gondii DNA was determined in seropositive subjects using PCR. The association between clinical data and infection was examined by bivariate analysis.

RESULTS

Anti-T. gondii IgG antibodies were found in 6/65 cases (9.2%) and in 21/195 controls (10.8%) (OR 0.84; 95% CI 0.32 to 2.18; p=0.81). The frequency of high (>150 IU/mL) antibody levels was similar among cases and controls (p=0.34). None of the anti-T. gondii IgG positive cases and four of the anti-T. gondii IgG positive controls had anti-T. gondii IgM antibodies (p=0.54). The prevalence of T. gondii DNA was comparable in seropositive cases and controls (16.7% and 25%, respectively; p=1.0). Seroprevalence of T. gondii infection was associated with a young age onset of disease (p=0.03), high Unified Parkinson Disease Rating Scale scores (p=0.04) and depression (p=0.02). Seropositivity to T. gondii infection was lower in patients treated with pramipexole than in patients without this treatment (p=0.01). However, none of the associations remained significant after Bonferroni correction.

CONCLUSIONS

The results do not support an association between T. gondii infection and Parkinson's disease. However, T. gondii infection might have an influence on certain symptoms of Parkinson's disease. Further research to elucidate the role of T. gondii exposure on Parkinson's disease is warranted.

Molecular and virulence characterization of Toxoplasma gondii strains isolated from humans in Portugal

Toxoplasma gondii is an apicomplexan parasite responsible for toxoplasmosis which infects all warm-blooded vertebrates, including mammals and birds. The majority of studies conducted in Europe have revealed that more than 80 % of strains isolated from human infections belong to genotype II, whereas genotypes I and III are responsible for a small number of cases. Atypical and recombinant strains are generally associated with more severe infections. In Portugal, there is a lack of data concerning genetic diversity as the classical typing studies in humans have never been performed. We aimed to determine the Sag2 and microsatellite-based (TUB2, TgM-A, W35, B17, B18) genotypes of T. gondii isolated from humans in Portugal, as well as to study their virulence in mice. We analyzed 48 strains from congenital and acquired toxoplasmosis collected during the last two decades. Sag2-based genotyping of T. gondii was achieved in all 48 strains where 35 (73 %) were classified as type II and 13 (27 %) were type I. The multilocus PCR of five microsatellites allowed the classification of 10 strains (21 %) as recombinant strains that had been previously identified as type II or I by Sag2 typing. Seven out of the 48 strains, including three type I, three recombinant, and one type I, were virulent in mice. This study constitutes the first evidence of recombinant strains circulating in Portugal in humans from congenital infection, highlighting the need for a better evaluation of these strains as their phenotype is still barely understood.

Seasonality of blood neopterin levels in the Old Order Amish

Seasonal changes in non-human animals and seasonal affective disorder (SAD) in humans are associated with immune activation in winter relative to summer. We intended to measure seasonal variation in neopterin, a marker of cellular immunity, and its interactions with gender and seasonality of mood. We studied 320 Amish from Lancaster, PA, USA (men = 128; 40%) with an average age [Standard deviation (SD)] of 56.7 (13.9) years. Blood neopterin level was measured with enzyme-linked immunosorbent assay (ELISA). Seasonality was measured with Seasonal Pattern Assessment Questionnaire (SPAQ). Statistical analysis included analysis of covariance (ANCOVAs) and multivariate linear regression. We also investigated interactions of seasonal differences in neopterin with gender, seasonality scores and estimation of SAD diagnosis. We found a significantly higher neopterin level in winter than in summer (p = 0.006). There were no significant gender or seasonality interactions. Our study confirmed the hypothesized higher neopterin level in winter. A cross sectional design was our major limitation. If this finding will be replicated by longitudinal studies in multiple groups, neopterin could be used to monitor immune status across seasons in demographically diverse samples, even if heterogeneous in gender distribution, and degree of seasonality of mood.

Mental Health Disorders Associated with Foodborne Pathogens

Human infections with foodborne pathogenic organisms are relatively well described in terms of their overt physical symptoms, such as diarrhea, abdominal cramps, vomiting, fever, and associated sequelae. Indeed, some of these are key for diagnosis and treatment, although it should be noted that, for some foodborne pathogens, the physical symptoms might be more diffuse, particularly those associated with some of the foodborne parasites. In contrast, the impact of these pathogens on mental health is less well described, and symptoms such as depression, anxiety, and general malaise are usually ignored when foodborne infections are recorded. Despite this, it is generally accepted that there are several psychiatric disorders of unknown etiology that may be associated with microbial pathogens. Depression, autism, hypochondriasis and anxiety, schizophrenia, and Tourette syndrome probably have multiple contributing causes, among which foodborne pathogens may play a decisive or contributory role, possibly sharing pathophysiological pathways with other environmental triggers. This review focuses on foodborne parasites and bacterial pathogens. Some foodborne parasites, such as metacestodes of Taenia solium and tissue cysts (bradyzoites) of Toxoplasma gondii , may affect mental health by directly infecting the brain. In contrast, bacterial infections and other parasitic infections may contribute to mental illness via the immune system and/or by influencing neurotransmission pathways. Thus, cytokines, for example, have been associated with depression and schizophrenia. However, infectious disease models for psychiatry require a more complete understanding of the relationship between psychiatric disorders and microbial triggers. This article reviews the current state of knowledge on the role of foodborne parasitic and bacterial pathogens in mental illness and identifies some of the gaps that should be addressed to improve diagnosis and treatment of mental health issues that are not solely related to psychiatric factors.

Association of Depressed Mood With Herpes Simplex Virus-2 Immunoglobulin-G Levels in Pregnancy

OBJECTIVE

Depressed mood is common in pregnancy, is associated with stress, and could result in immune suppression that may lead to latent herpes viral reactivation. This study investigated whether depressed mood is associated with higher herpes viral IgG levels in pregnant women.

METHODS

Complete cross-sectional data from 247 pregnant women were available for this substudy. The data included demographics, scores on the Perceived Stress Scale and Profile of Mood States (POMS), and a panel of serum IgG levels for human herpesviruses.

RESULTS

Only the herpes simplex virus type 2 (HSV-2) (genital herpes) IgG level was associated with Perceived Stress Scale and POMS-Depression/Dejection (POMS-D) score. Hierarchical multiple regression analysis was used to examine the association of POMS-D with herpesviral IgG levels adjusting for demographic variables. In the final model, African American race (β = .251, p < .001), older age (β = .199, p = .002), single marital status (β = -.304, p < .001), and depressed mood (β = .122, p = .04) were associated with HSV-2 IgG levels. In logistic regression, the strongest correlates of HSV IgG positivity were single marital status, followed by POMS-D scores and African American race.

CONCLUSION

Genital herpes is a concern in pregnancy. Antibody titers may indicate asymptomatic viral shedding, viral reactivation, or primary viral infection. Antibody levels may be higher because of the immune changes during pregnancy and potential immune effects of depressed mood causing reactivation of latent HSV-2.

The correlation between Toxoplasma gondii infection and prenatal depression in pregnant women

Previous studies have demonstrated that latent toxoplasmosis is associated with neuropsychiatric disorders. We evaluated the correlation between Toxoplasma gondii infection and prenatal depression. In this case-control study, we enrolled 116 depressed pregnant women and 244 healthy controls. The Edinburgh Postpartum Depression Scale (EPDS) was used to evaluate the depression symptom severity in study participants. All participants were screened for the anti-Toxoplasma IgG by enzyme-linked immunosorbent assay. Seroprevalence of T. gondii did not significantly differ between the depressed pregnant women and healthy controls (OR = 1.4; 95 % CI = 0.9-2.19; P = 0.142). T. gondii IgG titer was significantly higher in depressed women (18.6 ± 10.9 IUs) than those in the control group (13.6 ± 8.1 IUs) (z = -5.36, P < 0.001). The T. gondii-positive depressed women showed a positive correlation of T. gondii IgG titer with the EPDS scores (r = 0.52; P < 0.01). The mean EPDS score was also significantly higher in the T. gondii-positive depressed women (20.7 ± 2.7) compared with the controls (18.36 ± 2.7) (P < 0.001). The results obtained from the current study revealed that T. gondii infection might affect susceptibility to depression and severity of depressive symptoms in pregnant women, particularly in those patients who have high antibody titers. Further study is required to fully elucidate the characteristics and mechanisms of this association.

Latent toxoplasmosis is associated with neurocognitive impairment in young adults with and without chronic HIV infection

We evaluated the impact of latent toxoplasmosis (LT) on neurocognitive (NC) and neurobehavioural functioning in young adults with and without chronic HIV infection, using a standardised NC test battery, self-reported Beck Depression Inventory, Frontal System Behavior Scale, MINI-International Neuropsychiatric Interview and risk-assessment battery. 194 young adults (median age 24years, 48.2% males) with chronic HIV infection (HIV+) since childhood and 51 HIV seronegative (HIV-) participants were included. HIV+ individuals had good current immunological status (median CD4: 479 cells/μl) despite a low CD4 nadir (median: 93 cells/μl). LT (positive anti-Toxoplasma IgG antibodies) was present in one third of participants. The impairment rates in the HIV- with and without Toxo were not significantly different (p=0.17). However, we observed an increasing trend (p<0.001) in impairment rates with HIV and LT status: HIV-/LT- (6.1%); HIV-/LT+ (22%), HIV+/LT- (31%), HIV+/LT+ (49%). In a multivariable analysis using the entire study group there were main effects on cognition for HIV and also for LT. Within the HIV+ group LT was associated with worse performance globally (p=0.006), in memory (p=0.009), speed of information processing (p=0.01), verbal (p=0.02) and learning (p=0.02) domains. LT was not associated with depressive symptoms, frontal systems dysfunction or risk behaviors in any of the groups. HIV participants with lower Toxoplasma antibody concentration had worse NC performance, with higher GDS values (p=0.03) and worse learning (p=0.002), memory (p=0.006), speed of information processing (p=0.01) T scores. Latent Toxoplasmosis may contribute to NC impairment in young adults, including those with and without chronic HIV infection.

Seroepidemiology of Toxoplasma Gondii Infection in People Applying for Medical Certificates

Medical certificates are documents that state the health status of a person. This study aimed to determine the seroprevalence and risk factors for Toxoplasma gondii infection in applicants of medical certificates and to investigate seroprevalence association with characteristics of these individuals. We examined 404 applicants in a public health center in Durango City, Mexico for the presence of anti-Toxoplasma IgG and IgM antibodies using enzyme-linked immunoassays. Of the 404 subjects (mean age of 35.94 ± 13.01) studied, 29 (7.2%) were positive for anti-T. gondii IgG antibodies and 9 (31.0%) of them were also positive for anti-T. gondii IgM antibodies. IgG and IgM seropositivities were associated with vision impairment (P = 0.04) and a history of surgery (P = 0.03), respectively. Prevalence of high (>150 IU/ml) IgG antibody levels was associated with hearing impairment (P = 0.03), and histories of lymphadenopathy (P = 0.04) and miscarriages (P = 0.03). Multivariate analysis showed that T. gondii seropositivity was associated with being born out of Durango State (odds ratio [OR] = 4.65; 95% confidence interval [CI]: 1.25-17. 29; P = 0.02) and soil contact (OR = 4.27; 95% CI: 1.71-10.67; P = 0.002) and negatively associated with consumption of sheep meat (OR = 0.12; 95% CI: 0.02-0.65; P = 0.01). These results could be used for the design of optimal preventive measures against toxoplasmosis and its sequelae.

Toxoplasma gondii Infection and Mixed Anxiety and Depressive Disorder: A Case-Control Seroprevalence Study in Durango, Mexico

BACKGROUND

The parasite Toxoplasma gondii (T. gondii) may invade the brain and might induce behavioral changes. We sought to determine the association of T. gondii infection and mixed anxiety and depressive disorder.

METHODS

Through an age- and gender-matched case-control seroprevalence study, we examined 65 patients suffering from mixed anxiety and depressive disorder (WHO ICD-10 code: F41.2) attending in a public hospital of mental health and 260 control subjects without this disorder from the general population. Sera of participants were analyzed for anti-Toxoplasma IgG and IgM antibodies using enzyme-linked immunoassays.

RESULTS

Fifteen (23.1%) of the 65 patients and 18 (6.9%) of the 260 controls had anti-T. gondii IgG antibodies (odds ratio (OR): 4.03; 95% confidence interval (CI): 1.90 - 8.53; P < 0.001). The frequency of high (> 150 IU/mL) anti-T. gondii IgG levels was similar in cases and controls (OR: 0.25; 95% CI: 0.05 - 1.06; P = 0.05). Seroprevalence was similar in male cases and controls (P = 1.0); however, seroprevalence was significantly higher in female cases than in female controls (OR: 7.08; 95% CI: 2.83 - 17.67; P < 0.00001). Patients aged 31 - 50 years old had a significantly higher seroprevalence of T. gondii infection than controls of the same age group (OR: 21.04; 95% CI: 5.22 - 84.80; P < 0.00001). Anti-T. gondii IgM antibodies were found in four (26.7%) of the 15 anti-T. gondii IgG seropositive cases and in 10 (55.6%) of the 18 anti-T. gondii IgG seropositive controls (P = 0.15).

CONCLUSIONS

Results support for the first time an association between seropositivity to T. gondii and mixed anxiety and depressive disorder. Further research to confirm this association and to determine the seroepidemiology of T. gondii infection in patients with this disorder is needed.

Influence of Toxoplasma Gondii Infection on Symptoms and Signs of Menopause

Some symptoms of menopause have also been described in patients with toxoplasmosis. Whether Toxoplasma gondii (T. gondii) infection has any influence on clinical manifestations of menopause is yet unknown. We sought to determine whether T. gondii exposure is associated with symptoms and signs of menopause. We performed a cross-sectional study of women attending a public health center in Durango City, Mexico. Participants were examined for the presence of anti-Toxoplasma IgG and IgM antibodies using enzyme-linked immunoassays. A questionnaire including 47 symptoms and signs potentially associated with menopause was applied. Association of seroprevalence for T. gondii with clinical characteristics of women was assessed by bivariate and multivariate analyses. Bivariate analysis showed that bouts of rapid heartbeat, breast pain, electric shock sensation, dizziness, digestive problems, low back pain, and migraine were associated with seropositivity to either IgG anti-T. gondii alone or both IgG and IgM anti-T. gondii. Breast pain was the only variable that was found to be associated with IgG seropositivity to T. gondii by multivariate analysis: (OR = 2.84; 95% CI: 1.35–5.90; P = 0.005). Our results suggest that T. gondii exposure may influence on the clinical manifestations of menopause. Results deserve further research.

Toxoplasma Gondii Infection and Depression: A Case-Control Seroprevalence Study

We assessed the association of Toxoplasma gondii infection and depression in a sample of psychiatric patients and control subjects without depression. We performed an age- and gender-matched case-control study of 89 patients suffering from depression attended in a public psychiatric hospital in Durango City, Mexico and 356 control subjects without depression from the general population of the same city. Participants were tested for the presence of anti-Toxoplasma IgG and IgM antibodies using enzyme-linked immunoassays. Anti-T. gondii IgG antibodies were found in 11 (12.4%) of the 89 cases and in 22 (6.2%) of the 356 controls (OR = 2.14; 95% CI: 1.00-4.59; P = 0.04). Anti-T. gondii IgM antibodies were found in four (19%) of 21 anti-T. gondii IgG seropositive controls but not in 11 anti-T. gondii IgG seropositive cases (P = 0.27). Patients aged 30 years old and younger had a significantly higher seroprevalence of T. gondii infection than controls of the same age group (P = 0.001). Results of the present study suggest a potential association between T. gondii infection and depression. Furthers studies to confirm our results and to determine the epidemiology of T. gondii in young depressed patients should be conducted.

Use of human induced pluripotent stem cell-derived neurons as a model for Cerebral Toxoplasmosis

Toxoplasma gondii is a ubiquitous protozoan parasite with approximately one-third of the worlds' population chronically infected. In chronically infected individuals, the parasite resides primarily in cysts within neurons in the central nervous system. The chronic infection in immunocompetent individuals has been considered to be asymptomatic but increasing evidence indicates the chronic infection can lead to neuropsychiatric disorders such as Schizophrenia, prenatal depression and suicidal thoughts. A better understanding of the mechanism(s) by which the parasite exerts effects on human behavior is limited due to lack of suitable human neuronal models. In this paper, we report the use of human neurons derived from normal cord blood CD34+ cells generated via genetic reprogramming, as an in vitro model for the study T. gondii in neurons. This culture method resulted in a relatively pure monolayer of induced human neuronal-like cells that stained positive for neuronal markers, MAP2, NFL, NFH and NeuN. These induced human neuronal-like cells (iHNs) were efficiently infected by the Prugniad strain of the parasite and supported replication of the tachyzoite stage and development of the cyst stage. Infected iHNs could be maintained through 5 days of infection, allowing for formation of large cysts. This induced human neuronal model represents a novel culture method to study both tachyzoite and bradyzoite stages of T. gondii in human neurons.

Parasitic diseases of the central nervous system: lessons for clinicians and policy makers

Parasitic diseases of the central nervous system are associated with high mortality and morbidity, especially in resource-limited settings. The burden of these diseases is amplified as survivors are often left with neurologic sequelae affecting mobility, sensory organs, and cognitive functions, as well as seizures/epilepsy. These diseases inflict suffering by causing lifelong disabilities, reducing economic productivity, and causing social stigma. The complexity of parasitic life cycles and geographic specificities, as well as overlapping clinical manifestations in the host reflecting the diverse pathogenesis of parasites, can present diagnostic challenges. We herein provide an overview of these parasitic diseases and summarize clinical aspects, diagnosis, therapeutic strategies and recent milestones, and aspects related to prevention and control.

Beyond the association. Toxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta-analysis

OBJECTIVE

To perform a meta-analysis on studies reporting prevalence of Toxoplasma gondii (T. gondii) infection in any psychiatric disorder compared with healthy controls. Our secondary objective was to analyze factors possibly moderating heterogeneity.

METHOD

A systematic search was performed to identify studies into T. gondii infection for all major psychiatric disorders versus healthy controls. Methodological quality, publication bias, and possible moderators were assessed.

RESULTS

A total of 2866 citations were retrieved and 50 studies finally included. Significant odds ratios (ORs) with IgG antibodies were found in schizophrenia (OR 1.81, P < 0.00001), bipolar disorder (OR 1.52, P = 0.02), obsessive-compulsive disorder (OR 3.4, P < 0.001), and addiction (OR 1.91, P < 0.00001), but not for major depression (OR 1.21, P = 0.28). Exploration of the association between T. gondii and schizophrenia yielded a significant effect of seropositivity before onset and serointensity, but not IgM antibodies or gender. The amplitude of the OR was influenced by region and general seroprevalence. Moderators together accounted for 56% of the observed variance in study effects. After controlling for publication bias, the adjusted OR (1.43) in schizophrenia remained significant.

CONCLUSION

These findings suggest that T. gondii infection is associated with several psychiatric disorders and that in schizophrenia reactivation of latent T. gondii infection may occur.