Toxoplasmosis and neuropsychiatric diseases: can serological studies establish a clear relationship?

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The effect of chronic experimental toxoplasmosis on some brain neurotransmitters level and behavior changes

Toxoplasma is capable of causing long-lasting brain cysts in its hosts, which can lead to physiological disturbances in brain neurotransmitters and result in changes in the host's behavior. This study aimed to investigate these changes using an experimental model. Twenty-five female Wistar rats, weighing 220-220 g and six weeks old, were selected for the study. The rats were divided into two control and experimental groups. The experimental group was injected with 5 × 105 tachyzoites of Toxoplasma gondii (virulent RH strain) intra-peritoneally. Four months after the injection, the rats were subjected to behavioral tests, including learning, memory, depression, and locomotor activity tests. The rats were then euthanized, and their brain and serum samples were analyzed for dopamine and serotonin levels. To ensure the presence of cysts in the brain tissue, a PCR test and preparation of pathological slides from the brain tissue were performed. The results showed that the amount of dopamine in the brain of the infected group was significantly higher than that of the control group, while the level of serotonin in brain of the infected group was significantly lower than that of the control group (P < 0.05). However, no significant difference was observed in the amount of these neurotransmitters in the blood of the two groups (P > 0.05). Behavioral changes were evaluated, and it was found that the learning and memory levels of the infected rats were significantly lower than those of the control group (P < 0.05), but no difference was observed in locomotor activity between the two groups (P > 0.05). This experimental infection model indicated that changes in neurotransmitter levels lead to behavior changes. CONCLUSION: The presence of parasite cysts in the brain can affect some of the host's behaviors through changes in neurotransmitter levels. Therefore, there is a possibility that there is a relationship between the presence of Toxoplasma cysts in the brain and neurological disorders. The results of this study suggest that chronic toxoplasmosis may play a role in behavior changes in psychotic diseases.

Toxoplasma gondii infection and insomnia: A case control seroprevalence study

We determined the association between Toxoplasma gondii (T. gondii) infection and insomnia. Through an age-and gender-matched case-control study, 577 people with insomnia (cases) and 577 people without insomnia (controls) were tested for anti-T. gondii IgG and IgM antibodies using commercially available enzyme-immunoassays. Anti-T. gondii IgG antibodies were found in 71 (12.3%) of 577 individuals with insomnia and in 46 (8.0%) of 577 controls (OR = 1.62; 95% CI: 1.09–2.39; P = 0.01). Men with insomnia had a higher (16/73: 21.9%) seroprevalence of T. gondii infection than men without insomnia (5/73: 6.8%) (OR: 3.81; 95% CI: 1.31–11.06; P = 0.009). The rate of high (>150 IU/ml) anti-T. gondii IgG antibody levels in cases was higher than the one in controls (OR = 2.21; 95% CI: 1.13–4.31; P = 0.01). Men with insomnia had a higher (8/73: 11.0%) rate of high anti-T. gondii IgG antibody levels than men without insomnia (0/73: 0.0%) (P = 0.006). The rate of high anti-T. gondii IgG antibody levels in cases >50 years old (11/180: 6.1%) was higher than that (3/180: 1.7%) in controls of the same age group (OR: 3.84; 95% CI: 1.05–14.00; P = 0.05). No difference in the rate of IgM seropositivity between cases and controls was found (OR = 1.33; 95% CI: 0.57–3.11; P = 0.50). Results of this seroepidemiology study suggest that infection with T. gondii is associated with insomnia. Men older than 50 years with T. gondii exposure might be prone to insomnia. Further research to confirm the association between seropositivity and serointensity to T. gondii and insomnia is needed.

Seroprevalence of Toxoplasma gondii in Different Patient Groups in Our Hospital

OBJECTIVE

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite. It is regarded as an important cause of morbidity and mortality in congenital contamination and immunosuppressive patients. This study aimed to determine the seropositivity of T. gondii in various ages and patient groups, as well as to reveal the current immune status, especially in risk groups.

METHODS

Results of T. gondii serology conducted between 2015 and 2019 in the medical microbiology laboratory in a university hospital were retrospectively analyzed. In the study, anti-T. gondii IgM, anti-T. gondii IgG antibodies, and anti-T. gondii IgG avidity test results were investigated by the enzyme-linked fluorescent assay method. Additionally, seropositivity rates among immunosuppressed patients and pregnant women, which are risk groups for toxoplasmosis, were revealed. In the identification of the immunosuppressed patients, groups with significant immunosuppression were retrospectively determined by examining their files.

RESULTS

The serology of T. gondii was investigated in serum samples of a total of 20.875 individuals, among which 6.220 (29.8%) are males and 14.655 (70.2%) are females. Anti-T. gondii IgM and IgG positivity rates were significantly higher in women than in men. When all years are evaluated, IgM positivity in 16.448 patients and IgG positivity in 4.427 patients were investigated. In the 5-year period, T. gondii IgM seropositivity and T. gondii IgG seropositivity was among all the patients was 2.4% and 24.1%, respectively. While the rate of T. gondii IgG seropositivity in women of childbearing age was 36.1%, it was 42.4% in pregnant women and 14.6% in immunosuppressed patients.

CONCLUSION

T. gondii serology follow-up of pregnant women and immunosuppressed patients in terms of reactivity of latent infection should be advised and toxoplasmosis should be considered in suspicious clinical cases.

Detección molecular de Toxoplasma gondii en carnes para consumo humano en Ibagué, Colombia

Introducción. Toxoplasma gondii es un parásito con gran potencial zoonótico que puede infectar un amplio rango de huéspedes de sangre caliente, incluidos los animales del sector pecuario, lo que causa pérdidas a la industria. En el humano, es patógeno en personas inmunosuprimidas y afecta el desarrollo del feto en infecciones congénitas. Además, se asocia con diversos trastornos del comportamiento en personas sanas. El humano puede adquirir T. gondii al consumir carnes contaminadas mal cocidas.Objetivo. Determinar la positividad de T. gondii en carnes de consumo humano (res, pollo y cerdo) en Ibagué, Colombia.Materiales y métodos. Se utilizó la PCR convencional anidada y la secuencia del gen B1 de T. gondii como blanco de amplificación. Se tomaron 186 muestras de carne comercializada en la zona urbana de Ibagué (62 de res, 62 de pollo y 62 de cerdo) y se obtuvo el porcentaje de positividad en cada tipo de carne evaluada.Resultados. Se encontró un porcentaje de positividad de 18,8 % en las muestras, siendo la carne de cerdo la del mayor porcentaje (22,5 %; 14/62), seguida por las muestras de carne de res (19,3 %; 12/62) y de pollo (14,5 %; 9/62). Los mejores productos amplificados fueron secuenciados en Macrogen, y alineados con las secuencias del gen B1 depositadas en el GenBank, con lo que se confirmó su identidad.Conclusiones. Este es el primer estudio sobre prevalencia de T. gondii en carnes para consumo humano en Ibagué y el departamento del Tolima. Se demostró que los tres tipos de carne representan un riesgo para la infección en humanos a nivel local.

Toxoplasmosis: Targeting neurotransmitter systems in psychiatric disorders

The most common form of the disease caused by Toxoplasma gondii (T. gondii) is latent toxoplasmosis due to the formation of tissue cysts in various organs, such as the brain. Latent toxoplasmosis is probably a risk factor in the development of some neuropsychiatric disorders. Behavioral changes after infection are caused by the host immune response, manipulation by the parasite, central nervous system (CNS) inflammation, as well as changes in hormonal and neuromodulator relationships. The present review focused on the exact mechanisms of T. gondii effect on the alteration of behavior and neurotransmitter levels, their catabolites and metabolites, as well as the interaction between immune responses and this parasite in the etiopathogenesis of psychiatric disorders. The dysfunction of neurotransmitters in the neural transmission is associated with several neuropsychiatric disorders. However, further intensive studies are required to determine the effect of this parasite on altering the level of neurotransmitters and the role of neurotransmitters in the etiology of host behavioral changes.

Detection of Toxoplasma gondii oocysts on organic and conventionally grown produce

Toxoplasma gondii infection can result in toxoplasmosis and potential psychological effects. Research commonly focuses on infection through contact with cat fecal matter or consumption of contaminated meat. However, T. gondii oocysts can persist in the environment for years and may be present in soils and on soil-grown produce. Rates of oocyst DNA recovery from produce were high, with 18% of vegetable samples testing positive for T. gondii via PCR test and melt curve analysis. Radishes had significantly higher oocyst counts than arugula, collard greens, kale, lettuce, and spinach. There were no significant differences in oocyst detection rates between samples taken from organic farmer's markets and conventional grocery stores. This study demonstrates that these oocysts can transfer to produce grown both conventionally and using organic techniques.

Multi-pathogen infections and Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease associated with the overproduction and accumulation of amyloid-β peptide and hyperphosphorylation of tau proteins in the brain. Despite extensive research on the amyloid-based mechanism of AD pathogenesis, the underlying cause of AD is not fully understood. No disease-modifying therapies currently exist, and numerous clinical trials have failed to demonstrate any benefits. The recent discovery that the amyloid-β peptide has antimicrobial activities supports the possibility of an infectious aetiology of AD and suggests that amyloid-β plaque formation might be induced by infection. AD patients have a weakened blood-brain barrier and immune system and are thus at elevated risk of microbial infections. Such infections can cause chronic neuroinflammation, production of the antimicrobial amyloid-β peptide, and neurodegeneration. Various pathogens, including viruses, bacteria, fungi, and parasites have been associated with AD. Most research in this area has focused on individual pathogens, with herpesviruses and periodontal bacteria being most frequently implicated. The purpose of this review is to highlight the potential role of multi-pathogen infections in AD. Recognition of the potential coexistence of multiple pathogens and biofilms in AD's aetiology may stimulate the development of novel approaches to its diagnosis and treatment. Multiple diagnostic tests could be applied simultaneously to detect major pathogens, followed by anti-microbial treatment using antiviral, antibacterial, antifungal, and anti-biofilm agents.

Human Neural Stem Cell Systems to Explore Pathogen-Related Neurodevelopmental and Neurodegenerative Disorders

Building and functioning of the human brain requires the precise orchestration and execution of myriad molecular and cellular processes, across a multitude of cell types and over an extended period of time. Dysregulation of these processes affects structure and function of the brain and can lead to neurodevelopmental, neurological, or psychiatric disorders. Multiple environmental stimuli affect neural stem cells (NSCs) at several levels, thus impairing the normal human neurodevelopmental program. In this review article, we will delineate the main mechanisms of infection adopted by several neurotropic pathogens, and the selective NSC vulnerability. In particular, TORCH agents, i.e., Toxoplasma gondii, others (including Zika virus and Coxsackie virus), Rubella virus, Cytomegalovirus, and Herpes simplex virus, will be considered for their devastating effects on NSC self-renewal with the consequent neural progenitor depletion, the cellular substrate of microcephaly. Moreover, new evidence suggests that some of these agents may also affect the NSC progeny, producing long-term effects in the neuronal lineage. This is evident in the paradigmatic example of the neurodegeneration occurring in Alzheimer's disease.

Pathogenesis of cerebral toxocariasis and neurodegenerative diseases

Toxocara canis belongs to one of zoonotic parasites that commonly infects canines worldwide, and its eggs in host faeces may contaminate the food, water, soil and their fur as well as the larvae entrapped in the granuloma can infect paratenic hosts including mice and humans. Survivability of T. canis embryonated eggs under moist, cool conditions may be as long as 2-4 years or more. In paratenic hosts such as mice and humans, T. canis L3 larvae neither moult, grow, nor replicate and will wander through a number of internal organs in humans so as to cause Th2-dominant pathology in various internal organs as leading to neurotoxocariasis (NT), ocular toxocariasis (OT), or visceral larva migrans (VLM). Although the systemic immune response to T. canis has been widely reported, the immune response in the brain has received little attention. Differential cytokine expression and other brain injury-associated biomarkers or neurodegeneration-associated factors have been observed in infected versus uninfected outbred and inbred mice. Preliminary data have also suggested a possible link between significant memory impairment and cytokine production associated with T. canis infection in the hippocampus which has been long recognised as being responsible for learning and memory functions. Notably, it remains an enigma concerning cerebral invasion by T. canis larvae rarely induces a recognisable neurological syndrome or its involvement in neuropathological disorders in humans. Exploration of the relationship between host and parasite in the brain may elucidate the cryptic symptoms of human cerebral toxocariasis, with patients presenting with mental retardation, epilepsy, neurodegeneration and other central nervous system (CNS) disorders.

Human-leukocyte antigen class II genes in early-onset obsessive-compulsive disorder

Objective: The exact aetiology of obsessive-compulsive disorder (OCD) is unknown, although there is evidence to suggest a gene-environment interaction model. Several lines of evidence support a possible role of the immune system in this model. Methods: The present study explores the allele variability in HLA genes of class II (HLA-DRB1, HLA-DQB1) in a sample of 144 early-onset OCD compared with reference samples of general population in the same geographical area. Results: None of the 39 alleles identified (allele frequency >1%) showed significant differences between OCD and reference populations. Pooling the different alleles that comprised HLA-DR4 (including DRB1*04:01, DRB1*04:04 and DRB1*04:05 alleles) we observed a significantly higher frequency (X²₁ = 5.53, P = 0.018; OR = 1.64, 95% CI 1.08-2.48) of these alleles in the early-onset OCD sample (10.8%) than in the reference population (6.8%). Conclusions: Taking into account the role of HLA class II genes in the central nervous system, the results presented here support a role of the immune system in the pathophysiological model of OCD.

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.

Prevalence of toxoplasmosis and its association with dementia in older adults in Central Africa: a result from the EPIDEMCA programme

OBJECTIVE

We aimed at estimating the seroprevalence of Toxoplasma gondii (T. gondii) infection in older adults living in Central Africa and investigating its association with dementia using data from the Epidemiology of Dementia in Central Africa (EPIDEMCA) programme.

METHODS

A cross-sectional multicentre population-based study was carried out among participants aged 73 (±7) years on average, living in rural and urban areas of the Central African Republic and the Republic of Congo between November 2011 and December 2012. Blood samples were collected from each consenting participant. The detection of anti-T. gondii immunoglobulin G antibodies was performed in 2014 in France using a commercially available ELISA kit. Participants were interviewed using a standardised questionnaire including sociodemographic characteristics. DSM-IV criteria were required for a diagnosis of dementia. Multivariate binary logistic regression models were used to assess the association between toxoplasmosis infection and dementia.

RESULTS

Among 1662 participants, the seroprevalence of toxoplasmosis was 63.0% (95% confidence interval (CI): 60.7-65.3) overall, 66.6% (95%CI: 63.4-69.8) in Central African Republic and 59.4% (95%CI: 56.1-62.7) in the Republic of Congo. In multivariate analyses, toxoplasmosis status was significantly associated with increasing age (P = 0.006), Republic of Congo (P = 0.002), urban area (P = 0.001) and previous occupation (P = 0.002). No associations between dementia and toxoplasmosis status or anti-T. gondii IgG titres were found.

CONCLUSION

Toxoplasma gondii infection was not associated with dementia among older adults in Central Africa. Our findings are consistent with previous studies and add to the knowledge on the relationship between T. gondii infection and neurological disorders.

Toxoplasma gondii infection and behavioral outcomes in humans: a systematic review

Studies suggest that the protozoan Toxoplasma gondii can disturb human behavior. This study aimed to systematically review the scientific literature on the possible associations between Toxoplasma gondii infection and neurobehavioral abnormalities in humans. We reviewed and summarized the studies published since 1990. The descriptors used were related to T. gondii infection and behavioral outcomes in humans; the main databases of the medical literature were accessed. The results of eight original articles published between 1994 and 2016 were evaluated and described. The most common serological method was the enzyme immunoassay. Most of the researchers used validated instruments for behavioral evaluation. Seven studies reported some association between the prevalence of anti-T. gondii antibodies and some altered behavioral aspects in adult humans; these studies focused on adult population in Europe and the USA. The most reported behavioral deviations are related to greater impulsivity and aggressiveness. There are very few studies on this subject, which present some limitations for inference and conclusions: most were cross-sectional studies, with a small sample size and in similar populations. Investigations with a larger sample size of different population groups should be performed to evaluate multiple factors.

Potential impacts of poor communication on early diagnosis of HIV-associated neurocognitive disorder

AIM

To ascertain whether community-based healthcare providers were collecting appropriate information to identify patients at risk of HIV-associated neurocognitive disorder and whether related documentation was complete.

BACKGROUND

HIV-associated neurocognitive disorder is a treatable neurological condition that can affect more than 20% of those infected with the HIV. Signs and symptoms of cognitive impairment may be subtle; therefore, documentation of medical and social information could be beneficial in identifying those at risk.

DESIGN

Cross-sectional descriptive study.

METHODS

An audit of patient records was completed by two community-based interdisciplinary teams with particular attention to the documentation of clinical and social indicators for those at risk of HIV-associated neurocognitive disorder. Data were collected over weeks during 2015.

RESULTS

Data were retrieved from both electronic medical record systems and hard copy patient records. Documentation was incomplete in every patient record (N = 262), including the absence of important clinical data relating to nadir CD4 + T-cell count (91%), HIV viral load (36%), current caregiver (19%), and living circumstances (14%). Up to 40% of recorded medications and results were unconfirmed by the person's medical practitioner.

CONCLUSION

Poor documentation can lead to incomplete information, which can delay early intervention for those at risk of HIV-associated neurocognitive disorder. Collection and recording of patient data needs to be consistent, as complete documentation is essential for integrating care, provision of clinical support and, importantly, for identifying those at risk of developing HIV-associated neurocognitive disorder.

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

Recent evidence suggests the involvement of Toxoplasma gondii infection in the emergence of psychotic and affective disorders. In this report, we describe the case of a young Brazilian woman affected by recurrent ocular toxoplasmosis and presenting with a manic episode with psychotic features in the context of a diagnosis of Bipolar Disorder (BD), type I. We observed a relationship between ocular manifestations and the clinical course of bipolar illness, confirmed by molecular analyses (nested-PCR), as well as by the high level of T. gondii specific IgG. This case report is the first showing the presence of circulating parasite DNA at the time of occurrence of psychiatric symptoms, thus providing further support for a possible role of the parasite in the pathogenesis of some cases of BD.

Is Toxoplasma gondii a Trigger of Bipolar Disorder?

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

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

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

Humans as Superorganisms: How Microbes, Viruses, Imprinted Genes, and Other Selfish Entities Shape Our Behavior

Psychologists and psychiatrists tend to be little aware that (a) microbes in our brains and guts are capable of altering our behavior; (b) viral DNA that was incorporated into our DNA millions of years ago is implicated in mental disorders; (c) many of us carry the cells of another human in our brains; and (d) under the regulation of viruslike elements, the paternally inherited and maternally inherited copies of some genes compete for domination in the offspring, on whom they have opposite physical and behavioral effects. This article provides a broad overview, aimed at a wide readership, of the consequences of our coexistence with these selfish entities. The overarching message is that we are not unitary individuals but superorganisms, built out of both human and nonhuman elements; it is their interaction that determines who we are.

Hepatitis C virus antibody titers associated with cognitive dysfunction in an asymptomatic community-based sample

BACKGROUND

Hepatitis C virus (HCV) infection is associated with cognitive dysfunction in clinic-based studies. The risk could be attributed to factors such as antiviral medications, substance abuse, or coincidental infection.

AIM

The aim was to evaluate cognitive function in relation to HCV antibody titers in a community-based sample of asymptomatic individuals at low risk for substance abuse.

METHOD

Adults were ascertained from a community in Mansoura, Egypt, where HCV is endemic (n = 258). Cognitive performance was evaluated using the Arabic version of the Penn Computerized Neurocognitive Battery. Substance abuse and psychopathology were also assessed. Antibodies to HCV and Toxoplasma gondii (TOX), a common protozoan that can affect cognition, were estimated using serological IgG assays.

RESULTS

The prevalence of HCV and TOX infection was 17.6% and 52.9%, respectively. HCV antibody titers were significantly associated with worse function in four cognitive tests for accuracy and three tests for speed, after adjusting for covariates (p < .05, beta coefficients, 2.1-3.2). TOX antibody titers were associated with impaired accuracy in one test.

CONCLUSIONS

The association between HCV antibody titers and cognitive impairment is not mediated by antiviral treatment or substance abuse in this sample. Whether HCV has a causal role in the cognitive dysfunction should be investigated.

Cerebral Toxocariasis: Silent Progression to Neurodegenerative Disorders?

Toxocara canis and T. cati are highly prevalent nematode infections of the intestines of dogs and cats. In paratenic hosts, larvae do not mature in the intestine but instead migrate through the somatic tissues and organs of the body. The presence of these migrating larvae can contribute to pathology. Toxocara larvae can invade the brains of humans, and while case descriptions of cerebral toxocariasis are historically rare, improved diagnosis and greater awareness have contributed to increased detection. Despite this, cerebral or neurological toxocariasis (NT) remains a poorly understood phenomenon. Furthermore, our understanding of cognitive deficits due to toxocariasis in human populations remains particularly deficient. Recent data describe an enhanced expression of biomarkers associated with brain injury, such as GFAP, AβPP, transforming growth factor β1 (TGF-β1), NF-L, S100B, tTG, and p-tau, in mice receiving even low doses of Toxocara ova. Finally, this review outlines a hypothesis to explore the relationship between the presence of T. canis larvae in the brain and the progression of Alzheimer's disease (AD) due to enhanced AD-associated neurodegenerative biomarker expression.

Does the informal caregiver notice HIV associated mild cognitive impairment in people living with HIV?

HIV associated minor neurocognitive disorder (MND) may be difficult to identify as key signs and symptoms (S & S) may be due to other clinical conditions. Using a self-assessment booklet "HIV and associated MND" we recruited 123 people living with HIV (PLHIV) from three sites: two hospital HIV clinics and a sexual health clinic in Sydney, Australia. Patients may down play S & S. Caregivers may notice subtle changes. By including caregivers, we aimed to find whether the caregivers noticed S & S undetected by the PLHIV. This is a sub-study of a prospective observational multi-site study aimed to validate the usefulness of a patient self-assessment tool (HIV-associated MND booklet). Using the booklet, participants and their caregivers subsequently identified S & S of MND. Sixty-four per cent (79) did not nominate a caregiver to be contacted. Participants from 2 sites 44 (36%) nominated caregivers to be contacted. Twenty-five caregivers identified more than four S & S of MND. S & S reported most by caregivers related to participants being more tired at the end of the day (76%). Participants agreed (77%). Participants also reported that they found it more difficult to remember things such as taking medications or attending medical appointments (67%). The most agreed on symptom was the requirement for increased concentration to get the same things done (Kappa P 0.599 <0.001 and McNemar 0.289). For each question at least one caregiver identified a symptom when the PLHIV did not. Caregivers were more likely than participants to report irritability and communication difficulties. It is important to include caregivers when investigating PLHIV for MND, as caregivers may validate the experience of the patient, and may also be uniquely placed to identify S & S not otherwise identified.

Toxoplasma gondii-induced neuronal alterations

The zoonotic pathogen Toxoplasma gondii infects over 30% of the human population. The intracellular parasite can persist lifelong in the CNS within neurons modifying their function and structure, thus leading to specific behavioural changes of the host. In recent years, several in vitro studies and murine models have focused on the elucidation of these modifications. Furthermore, investigations of the human population have correlated Toxoplasma seropositivity with changes in neurological functions; however, the complex underlying mechanisms of the subtle behavioural alteration are still not fully understood. The parasites are able to induce direct modifications in the infected cells, for example by altering dopamine metabolism, by functionally silencing neurons as well as by hindering apoptosis. Moreover, indirect effects of the peripheral immune system and alterations of the immune status of the CNS, observed during chronic infection, might also contribute to changes in neuronal connectivity and synaptic plasticity. In this review, we will provide an overview and highlight recent advances, which describe changes in the neuronal function and morphology upon T. gondii infection.

Different presence of Chlamydia pneumoniae, herpes simplex virus type 1, human herpes virus 6, and Toxoplasma gondii in schizophrenia: meta-analysis and analytical study

In the present study we have performed both a meta-analysis and an analytical study exploring the presence of Chlamydia pneumoniae, herpes simplex virus type 1, human herpes virus 6, and Toxoplasma gondii antibodies in a sample of 143 schizophrenic patients and 143 control subjects. The meta-analysis was performed on papers published up to April 2014. The presence of serum immunoglobulin G and immunoglobulin A was performed by enzyme-linked immunosorbent assay test. The detection of microbial DNA in total peripheral blood was performed by nested polymerase chain reaction. The meta-analysis showed that: 1) C. pneumoniae DNA in blood and brain are more common in schizophrenic patients; 2) there is association with parasitism by T. gondii, despite the existence of publication bias; and 3) herpes viruses were not more common in schizophrenic patients. In our sample only anti-Toxoplasma immunoglobulin G was more prevalent and may be a risk factor related to schizophrenia, with potential value for prevention.

Spinal cord pathology in chronic experimental Toxoplasma gondii infection

Infection with the protozoan Toxoplasma (T.) gondii causes chronic infection of the central nervous system and can lead to life-threatening encephalomyelitis in immunocompromised patients. While infection with T. gondii has long time been considered asymptomatic in immunocompetent hosts, this view is challenged by recent reports describing links between seropositivity and behavioral alterations. However, past and current researches are mainly focused on the brain during Toxoplasma encephalitis, neglecting the spinal cord as a key structure conveying brain signals into motion. Therefore, our study aimed to fill the gap and describes the spinal cord pathology in an experimental murine model of toxoplasmosis. In the spinal cord, we found distinct histopathological changes, inflammatory foci and T. gondii cysts similar to the brain. Furthermore, the recruitment of immune cells from the periphery was detected. Moreover, resident microglia as well as recruited monocytes displayed an increased MHC classes I and II expression. Additionally, the expression of pro- and anti-inflammatory cytokines was enhanced in the brain as well as in the spinal cord. In summary, the pathology observed in the spinal cord was similar to the previously described changes in the brain during the infection. This study provides the first detailed description of histopathological and immunological alterations due to experimental T. gondii induced myelitis in mice. Thus, our comparison raises awareness of the importance of the spinal cord in chronic T. gondii infection.

Chronic murine toxoplasmosis is defined by subtle changes in neuronal connectivity

Recent studies correlate chronic Toxoplasma gondii (T. gondii) infection with behavioral changes in rodents; additionally, seropositivity in humans is reported to be associated with behavioral and neuropsychiatric diseases. In this study we investigated whether the described behavioral changes in a murine model of chronic toxoplasmosis are associated with changes in synaptic plasticity and brain neuronal circuitry. In mice chronically infected with T. gondii, magnetic resonance imaging (MRI) data analysis displayed the presence of heterogeneous lesions scattered throughout all brain areas. However, a higher density of lesions was observed within specific regions such as the somatosensory cortex (SSC). Further histopathological examination of these brain areas indicated the presence of activated resident glia and recruited immune cells accompanied by limited alterations of neuronal viability. In vivo diffusion-tensor MRI analysis of neuronal fiber density within the infected regions revealed connectivity abnormalities in the SSC. Altered fiber density was confirmed by morphological analysis of individual, pyramidal and granule neurons, showing a reduction in dendritic arbor and spine density within the SSC, as well as in the hippocampus. Evaluation of synapse efficacy revealed diminished levels of two key synaptic proteins, PSD95 and synaptophysin, within the same brain areas, indicating deficits in functionality of the synaptic neurotransmission in infected mice. Our results demonstrate that persistent T. gondii infection in a murine model results in synaptic deficits within brain structures leading to disturbances in the morphology of noninfected neurons and modified brain connectivity, suggesting a potential explanation for the behavioral and neuropsychiatric alterations.

Searching for the immune basis of obsessive-compulsive disorder

The etiopathogenesis of obsessive-compulsive disorder (OCD) remains elusive. Clinical observation of the elevated frequency of obsessive-compulsive symptoms in patients with rheumatic fever, a post-streptococcal autoimmune disease, prompted the study of immune parameters in OCD. Anti-basal ganglia antibodies have been described in a subset of OCD patients. The assessment of circulating cytokines and immune cells confirmed unequivocal changes in at least some patients, although it is difficult to establish a particular immune profile in OCD. Several factors, including the use of psychotropic drugs and the presence of comorbid conditions, seem to influence these immune parameters.

High prevalence of Toxoplasma gondii oocyst shedding in stray and pet cats (Felis catus) in Virginia, United States

Background

The protozoan Toxoplasma gondii is the causative agent of toxoplasmosis, with complications varying from mental disease to death. While human infection can occur via ingestion of tissue cysts from infected meat, most human infection comes from oocysts. Cats are the only definitive host, and thus shedding of oocysts by cats provides the ultimate source of toxoplasmosis.

Methods

While most studies in the area use seroprevalence to monitor Toxoplasma incidence in cat populations, this provides only a history of infection. This study used PCR detection of oocysts from cat feces to more accurately estimate the numbers of cats producing oocysts and thus posing an active health risk. DNA sequencing was use to confirm the identity of the PCR products.

Results

Of the 49 cats tested, 9 yielded PCR products of the expected size. Six of the nine were determined by sequence analysis to be false positives, while three products were true positives. Overall, 6% of cats examined were found to be actively shedding oocysts.

Conclusions

The incidence of oocyst shedding in the cat population studied was significantly higher than expected and higher than found in most cat populations world-wide. Of equal importance, the primers tested were shown to produce PCR products of multiple sizes and non-target products of expected size. We detected false positives at a higher rate than true positives, emphasizing the need for confirmatory analysis. Further research may produce better protocols for Toxoplasma detection from cat fecal samples.

A sero-survey of toxoplasmosis in farm and non-farm children from Wisconsin, United States, 1997-1999

BACKGROUND

Toxoplasmosis is among the most widespread and prevalent zoonosis in the world. People can become infected through ingestion of oocysts shed by felids or of tissue cysts contained in meat from infected animals. Acute infection can result in a wide spectrum of consequences, including flu-like illness and retinitis, as well as congenital infection in pregnant women. Severe disease can occur, especially if people are immunocompromised. Frequency of human infection varies substantially by region due to ecological, social, and cultural factors. The most recent nationwide prevalence estimates in children from United States were 3.6% in 6-11 year olds and 5.8% in 12-19 year olds. Because of the limited knowledge of the occurrence of common zoonotic pathogens in children in the United States, the objective of this study was to estimate the sero-prevalence of T. gondii-specific antibodies in children from the Marshfield area in Wisconsin and to examine the association between sero-positivity and farm living.

METHODS

Banked sera from 342 Wisconsin children collected in 1997-1999, aged 2 to 18 years, were tested for Toxoplasma gondii-specific IgG antibodies using ELISA. Recorded information included age, sex, and whether the child resided on a farm. Impact of assay accuracy, sensitivity and specificity, on sero-prevalence was examined using Bayesian methods.

RESULTS

Observed prevalence of T. gondii-specific antibodies was 10.8% (37/347). Adjusting for sensitivity and specificity of the assays yielded a prevalence estimate of 8.0% (95% probability interval: 4%-12.4%). Children living on a farm had a 5 times higher odds of T. gondii-specific antibodies than children not living on a farm (OR=5.08, 95% CI: 2.2-11.6).

CONCLUSION

Results suggest that even in apparently low-risk populations, the true extent of the infection in children is significant. In this study population, children living on farms were differentially exposed, with earlier and higher infection risk than children not living on farms. Findings highlight the need to increase awareness about toxoplasmosis acquired early in life and to improve our understanding of the ecology of T. gondii in rural environments from developed and developing countries.