Seropositivity and serointensity of Toxoplasma gondii antibodies and DNA among patients with schizophrenia

Seroprevalence and sociodemographic characteristics of Toxoplasma gondii infection in patients with psychiatric disorders in Malaysia

Toxoplasma gondii is a neurotropic protozoan parasite that affects neuronal processing in the brain. This study aimed to investigate the prevalence of T. gondii infection in psychiatric disorder patients. We also investigated the potential association between sociodemographic, clinical manifestation, and behavior of Toxoplasma-seropositive patients with psychiatric disorders. Commercial ELISAs (IgG, IgM, and IgG avidity) using serum and PCR using buffy coat were performed on samples from 54 individuals in each of the following groups: patients diagnosed with depressive disorder, bipolar disorder, and schizophrenia, as well as psychiatrically healthy subjects (control group). They were recruited from the Hospital Universiti Sains Malaysia in Kelantan, Malaysia. Of 54 patients with depressive disorder, 24/54 (44.4 %) were seropositive for IgG, and four (16.7 %) were IgG+/IgM+. Among the latter, a high avidity index indicating a past infection was observed in half of the samples (50.0 %), and the other half (50.0 %) showed a low avidity index, indicating a possible recent infection. Meanwhile, 30/54 (55.6 %) patients with bipolar disorder were seropositive for IgG+, five (16.7 %) were IgG+/IgM+, and four of them had a high avidity index, and one had a low avidity index. Patients with schizophrenia showed 29/54 (53.7 %) seropositive for IgG, two of them (6.9 %) were IgG+/IgM+; one of latter had a high avidity index, and one had a low avidity index. Of 54 people in the control group, 37.0 % (20/54) were seropositive for T. gondii IgG antibodies. However, no significant difference was observed in seroprevalence between the control group and each patient group. No PCR-positive results were documented. A Chi-Square and multiple logistic regression showed that age (p = 0.031), close contact with cats/pets (p = 0.033) and contact with soil (p = 0.012) were significantly associated with Toxoplasma seropositivity in patients with psychiatric disorders. Additional research is needed to elucidate the causal relationships and underlying mechanisms.

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.

Metabolomic Profiling Reveals Common Metabolic Alterations in Plasma of Patients with Toxoplasma Infection and Schizophrenia

Toxoplasma gondii is an opportunistic protozoan parasite known to affect the human brain. The infection has been associated with an increased incidence of schizophrenia; however, the link between the two conditions remains unclear. This study aimed to compare the plasma metabolome of schizophrenia and non-schizophrenia subjects with or without Toxoplasma infection. Untargeted metabolomic profiling was carried out by liquid chromatography-mass spectrometry. Elevation of the α-hydroxyglutaric acid level and reduced adenosine monophosphate, inosine, hypoxanthine and xanthine were found in the subjects with either toxoplasmosis or schizophrenia alone. These results suggest that purine catabolism is a common metabolic alteration in Toxoplasma infection and schizophrenia. The roles of these metabolites on the pathogenesis of schizophrenia in relation to Toxoplasma infection warrant further studies.

Seroprevalence of ToRCH Pathogens in Southeast Asia

ToRCH is the acronym for several pathogens associated with pregnancy complications and sequelae in the unborn or newborn child. Particularly primary infections during pregnancy are associated with increased risk. Seroprevalence data of ToRCH infections are important, especially in countries with weak disease surveillance systems, to estimate immunity and vaccination levels, as well as exposure rates and thus the risk of infection during pregnancy. A systematic literature search spanning a 30-year time period was conducted to identify serosurveys on ToRCH pathogens in Southeast Asia. The 96 identified studies showed that some pathogens were well studied, while only limited data were available for others. Studies from the better-developed countries of the region were more abundant. Moreover, seroprevalence data were often limited to a certain geographical region within the country or to certain cohorts, there was an evident lack of recent serosurveys, and the study quality was often not adequate. Well-designed and area-wide serosurveys of ToRCH pathogens are clearly warranted. If combined with risk factor analysis, these studies may guide the development and implementation of effective measures for infection prevention, especially during pregnancy. In addition, educational programs for health care workers and for pregnant women during antenatal care are urgently needed.

Association between exposure to toxoplasmosis and major psychiatric disorders: a systematic review

Objective:

To assess the association between exposure to toxoplasmosis and major psychiatric disorders through a systematic review of the literature.

Methods:

The literature review was performed in the MEDLINE, SciELO, and PsycINFO databases. To evaluate the quality of the studies included in the review, the Newcastle-Ottawa Scale was used.

Results:

Thirty-one studies were included, and the majority found an association between exposure to toxoplasmosis and schizophrenia or bipolar disorder (58.3 and 54.5% of the included papers, respectively), but not major depressive disorder. We found no significant difference in mean quality scores between studies that corroborated and contradicted the association hypothesis for either schizophrenia or bipolar disorder. All included papers were considered at least satisfactory according to the Newcastle-Ottawa Scale (total scores ≥ 6 out of 9).

Conclusion:

Although there was no association between exposure to toxoplasmosis and major depressive disorder, the results indicate an association with both bipolar disorder and schizophrenia, despite their heterogeneity. Further studies should be performed with more specific variables so that the nature of these relationships can be elucidated.

Depression and Toxoplasma gondii infection: assess the possible relationship through a seromolecular case-control study

Depression disorder is one of the most common psychological recognitions that characterized by sadness, low self-confidence, and disinterest in every activity. Considering evidence showing the effects of toxoplasmosis on the psychological disease, this study conducted to investigate the serological and molecular aspects of Toxoplasma gondii infection among patients with depression. In this study, after selecting the patients with depression and control groups under the supervision of a psychologist, the blood samples were collected and the serum samples and buffy coat were separated. The specific anti-Toxoplasma IgG antibodies in serum samples were evaluated using the commercial ELISA kit. Then the desired region of the Toxoplasma B1 gene was amplified using the specific primers. To confirm the specificity of primers to amplify the B1 gene of Toxoplasma, the extracted PCR product was sequenced. The overall prevalence of toxoplasmosis in patients with depression was 59.8 and 60.19% by ELISA and PCR, respectively. In the control group, the prevalence of Toxoplasma was 56.3 and 40.2% by serology and PCR. There was a significant correlation between the prevalence of toxoplasmosis and depression. Moreover, a significant difference was found between the variables of age, sex, kind of nutrition, level of education and toxoplasmosis among the two cases and control groups. The higher prevalence of Toxoplasma infection among patients with depression compared with the control group indicates the probable impact of this parasite on depression and exacerbates its symptoms, which requires special attention of specialist physicians and patient's relatives.

Molecular Detection and Genetic Diversity of Toxoplasma gondii Oocysts in Cat Faeces from Klang Valley, Malaysia, Using B1 and REP Genes in 2018

The major route for Toxoplasma gondii (T. gondii) infection is through the ingestion of foods contaminated with oocyst from cat faeces. The microscopic detection of T. gondii oocysts in cat faeces is challenging, which contributes to the failure of detecting or differentiating it from other related coccidian parasites. This study aims to detect T. gondii oocysts in cat faeces using two multicopy-target PCR assays and to evaluate their genetic diversity. Cat faecal (200) samples were collected from pet cats (PCs; 100) and free-roaming cats (FRCs; 100) within Klang Valley, Malaysia, and screened for coccidian oocysts by microscopy using Sheather's sucrose floatation. PCR assays were performed on each faecal sample, targeting a B1 gene and a repetitive element (REP) gene to confirm T. gondii oocysts. Additionally, the PCR amplicons from the REP gene were sequenced to further confirm T. gondii-positive samples for phylogenetic analysis. Microscopy detected 7/200 (3.5%) T. gondii-like oocysts, while both the B1 gene and the REP gene detected 17/200 (8.5%) samples positive for T. gondii. All samples that were microscopically positive for T. gondii-like oocysts were also shown to be positive by both B1 and REP genes. The BLAST results sequenced for 16/200 (8.0%) PCR-positive T. gondii samples revealed homology and genetic heterogeneity with T. gondii strains in the GenBank, except for only one positive sample that did not show a result. There was almost perfect agreement (k = 0.145) between the two PCR assays targeting the B1 gene and the REP gene. This is the first report on microscopic, molecular detection and genetic diversity of T. gondii from cat faecal samples in Malaysia. In addition, the sensitivities of either the B1 gene or REP gene multicopy-target PCR assays are suitable for the accurate detection of T. gondii from cat faeces.

Majid R. A Review on the Prevalence of Toxoplasma gondii in Humans and Animals Reported in Malaysia from 2008-2018

Toxoplasmosis is a disease caused by the protozoan parasite Toxoplasma gondii (T. gondii). Human toxoplasmosis seroprevalence in Malaysia has increased since it was first reported in 1973 as shown in previous reviews of 1991 and 2007. However, over a decade since the last review, comprehensive data on toxoplasmosis in Malaysia is lacking. This work aimed at reviewing articles on toxoplasmosis research in Malaysia in order to identify the research gaps, create public awareness, and efforts made so far and proffer management options on the disease. The present review examines the available published research articles from 2008 to 2018 related to toxoplasmosis research conducted in Malaysia. The articles reviewed were retrieved from nine credible databases such as Web of Science, Google Scholar, ScienceDirect, PubMed, Scopus, Springer, Wiley online library, Ovid, and Cochrane using the keywords; Malaysia, toxoplasmosis, Toxoplasma gondii, toxoplasma encephalitis, seroprevalence, human immunodeficiency virus (HIV) patients, pregnant women, genotype strain, anti-toxoplasma antibodies, felines, and vaccine. The data highlighted seropositive cases from healthy community members in Pangkor Island (59.7%) and among migrant workers (57.4%) at alarming rates, as well as 42.5% in pregnant women. Data on animal seroprevalence were limited and there was no information on cats as the definitive host. Genetic characterization of Toxoplasma gondii from HIV patients; pregnant women, and domestic cats is lacking. This present review on toxoplasmosis is beneficial to researchers, health workers, animal health professionals, and policymakers. Therefore, attention is required to educate and enlighten health workers and the general public about the risk factors associated with T. gondii infection in Malaysia.

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

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

Associations of mental disorders and neurotropic parasitic diseases: a meta-analysis in developing and emerging countries

BACKGROUND

Although they are declining worldwide, neurotropic parasitic diseases are still common in developing and emerging countries. The aim of this study was to estimate the pooled prevalence and pooled association measures of comorbidities between mental disorders (anxiety, depression, bipolar disorder, and schizophrenia) and neurotropic parasitic diseases (malaria, cysticercosis, toxoplasmosis, human African trypanosomiasis, Chagas disease, and human toxocariasis) in developing and emerging countries.

METHODS

As the first meta-analysis on this topic, this study was performed in accordance with PRISMA guidelines. The protocol was registered in PROSPERO (N°CRD42017056521). The Medline, Embase, Lilacs, and Institute of Epidemiology and Tropical Neurology databases were used to search for articles without any restriction in language or date. We evaluated the quality of studies independently by two investigators using the Downs and Black assessment grid and pooled estimates using the random-effects method from CMA (Comprehensive Meta Analysis) Version 3.0.

RESULTS

In total, 18 studies published between 1997 and 2016 met our inclusion criteria. We found that the prevalence of anxiety and depression in people suffering from Chagas disease and/or neurocysticercosis was 44.9% (95% CI, 34.4-55.9). In 16 pooled studies that included 1782 people with mental disorders and 1776 controls, toxoplasmosis and/or toxocariasis were associated with increased risk of schizophrenia and/or bipolar disorders (odds ratio = 2.3; 95% CI, 1.7-3.2). Finally, toxocariasis and/or toxoplasmosis were associated with an increased risk of the onset of schizophrenia (odds ratio = 2.4; 95% CI, 1.7-3.4).

CONCLUSION

Our pooled estimates show that the associations between diseases studied are relatively high in developing and emerging countries. This meta-analysis supports the hypothesis that toxoplasmosis could be the cause of schizophrenia. These findings could prove useful to researchers who want to further explore and understand the associations studied.

Serological and molecular detection of Toxoplasma gondii in terrestrial and marine wildlife harvested for food in Nunavik, Canada

BACKGROUND

Toxoplasma gondii, a zoonotic protozoan parasite, infects mammals and birds worldwide. Infection in humans is often asymptomatic, though illnesses can occur in immunocompromised hosts and the fetuses of susceptible women infected during pregnancy. In Nunavik, Canada, 60% of the Inuit population has measurable antibodies against T. gondii. Handling and consumption of wildlife have been identified as risk factors for exposure. Serological evidence of exposure has been reported for wildlife in Nunavik; however, T. gondii has not been detected in wildlife tissues commonly consumed by Inuit.

METHODS

We used a magnetic capture DNA extraction and real-time PCR protocol to extract and amplify T. gondii DNA from large quantities of tissues (up to 100 g) of 441 individual animals in Nunavik: 166 ptarmigan (Lagopus lagopus), 156 geese (Branta canadensis and Chen caerulescens), 61 ringed seals (Pusa hispida), 31 caribou (Rangifer tarandus) and 27 walruses (Odobenus rosmarus).

RESULTS

DNA from T. gondii was detected in 9% (95% CI: 3-15%) of geese from four communities in western and southern Nunavik, but DNA was not detected in other wildlife species including 20% (95% CI: 12-31%) of ringed seals and 26% (95% CI: 14-43%) of caribou positive on a commercial modified agglutination test (MAT) using thawed heart muscle juice. In geese, tissue parasite burden was highest in heart, followed by brain, breast muscle, liver and gizzard. Serological results did not correlate well with tissue infection status for any wildlife species.

CONCLUSIONS

To our knowledge, this is the first report on the detection, quantification, and characterization of DNA of T. gondii (clonal lineage II in one goose) from wildlife harvested for food in Nunavik, which supports the hypothesis that migratory geese can carry T. gondii into Nunavik where feline definitive hosts are rare. This study suggests that direct detection methods may be useful for detection of T. gondii in wildlife harvested for human consumption and provides data needed for a quantitative exposure assessment that will determine the risk of T. gondii exposure for Inuit who harvest and consume geese in Nunavik.

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

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

A Case-Control Seroprevalence Study on the Association Between Toxoplasma gondii Infection and Bipolar Disorder

Background and Aims: Infection with the parasite Toxoplasma gondii has been associated with bipolar disorder in several countries other than Mexico. Therefore, we sought to determine the association between seropositivity to T. gondii and bipolar disorder in a Mexican population. Methods: We performed an age- and gender-matched case-control study of 66 patients with bipolar disorder (WHO International Classification of Diseases, 10th Revision code: F31) and 396 subjects without this disorder from the general population. Anti-Toxoplasma immunoglobulin G (IgG) and IgM antibodies were determined using commercially available enzyme-linked immunoassays. Results: Six (9.1%) of the 66 patients with bipolar disorder and 22 (5.6%) of the 396 controls had anti-T. gondii IgG antibodies (odds ratio [OR] = 1.7; 95% confidence interval [CI] = 0.66-4.36; P = 0.26). Stratification by gender and age did not show a difference in seroprevalence between cases and controls. The frequency of high (> 150 international units/ml) anti-T. gondii IgG levels was similar in cases (n = 2) and in controls (n = 12) (OR = 1.0; 95% CI = 0.21-4.57; P = 1.00). Stratification by International Classification of Diseases, 10th Revision F31 codes showed that patients with F31.3 code had a higher seroprevalence of T. gondii infection than their age- and gender-matched controls (OR = 16.4; 95% CI = 1.25-215.09; P = 0.04). None of the six anti-T. gondii IgG-seropositive patients with bipolar disorder and 4 (18.2%) of the 22 anti-T. gondii IgG-seropositive controls had anti-T. gondii IgM antibodies (P = 0.54). Conclusions: Our results suggest that T. gondii seropositivity is not associated with bipolar disorder in general. However, a specific type of bipolar disorder (F31.3) might be associated with T. gondii seropositivity. Further research to elucidate the role of T. gondii infection in bipolar disorder is needed.

Foxes (Vulpes vulpes) as sentinels for parasitic zoonoses, Toxoplasma gondii and Trichinella nativa, in the northeastern Canadian Arctic

Outbreaks of Toxoplasma gondii and Trichinella spp. have been recurring for decades among Inuit of Nunavik, northeastern Canada. Contact with wildlife has been identified as a risk factor for Inuit exposure to T. gondii, but reservoirs have yet to be confirmed based on direct detection of DNA or organism. Similarly, little is known about the occurrence of Trichinella spp. in wildlife species of Nunavik other than walrus (Odobenus rosmarus) and bears (Ursus americanus, Ursus maritimus). Foxes (Vulpes vulpes) were targeted as possible sentinels for T. gondii and Trichinella spp. because of their high trophic position within the Arctic food chain as carnivorous scavengers. A total of 39 red foxes were sampled from four communities in southern and western Nunavik between November 2015 and September 2016. For the first time in wildlife, a novel magnetic capture DNA extraction and real-time PCR technique was used to isolate and detect T. gondii DNA from the heart and brain of foxes. A double separatory funnel digestion method followed by multiplex PCR was used to recover and genotype larvae of Trichinella spp. from tongues of foxes. Seroprevalence based on detection of antibodies to T. gondii was 41% (95% CI: 27-57%) using a commercially available modified agglutination test (MAT). Detection of DNA of T. gondii and larvae of Trichinella nativa (T2) occurred in 44% (95% CI: 28-60%) and 36% (95% CI: 21-51%) of foxes, respectively. Coinfection with both T. nativa and T. gondii occurred among 23% (95%CI: 13-38%) of foxes which can be attributed to co-transmission from prey and scavenged species in their diet. There was only moderate agreement between T. gondii serology and direct detection of T. gondii DNA using the MC-PCR technique (Kappa test statistic: 0.321), suggesting that using both methods in tandem can increase the sensitivity of detection for this parasite. These findings show that foxes are good sentinels for circulation of parasitic zoonoses in terrestrial northern ecosystems since they are highly exposed, show measurable indicators of infection and do not serve as exposure sources for humans.

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.