Reviews – Toxoplasma gondii & Human Phenotype

Seroprevalence of Toxoplasma gondii infection in cancer patients: A systematic review and meta-analysis

February 4, 2020
Anvari, D., Sharif, M., Sarvi, S., Aghayan, S. A., Gholami, S., Pagheh, A. S., Hosseini, S. A., Saberi, R., Chegeni, T. N., Hosseininejad, Z., Daryani, A.
Microbial Pathogenesis 2019, 129: 30 - 42

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Relationship between toxoplasmosis and obsessive compulsive disorder: A systematic review and meta-analysis

February 1, 2020
Nayeri Chegeni, T., Sarvi, S. Amouei, A. Moosazadeh, M. Hosseininejad, Z. Aghayan, S. A. Daryani, A.
PLoS Neglected Tropical Diseases 19, 13

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Background A few studies investigated the relationship between toxoplasmosis and mental disorders, such as obsessive compulsive disorder (OCD). However, the specific nature of the association between Toxoplasma gondii (T. gondii) infection and OCD is not yet clear. The aim of this study was to collect information on the relationship between OCD and toxoplasmosis and assess whether patients with toxoplasmosis are prone to OCD. Methods For the purpose of this study, 6 major electronic databases and the Internet search engine Google Scholar were searched for the published articles up to July 30(th), 2018 with no restriction of language. The inverse variance method and the random effect model were used to combine the data. The values of odds ratio (OR) were estimated at 95% confidence interval (CI). Results A total of 9 case-control and 3 cross-sectional studies were included in our systematic review. However, 11 of these 12 articles were entered into the meta-analysis containing 9873 participants, out of whom 389 were with OCD (25.96% positive for toxoplasmosis) and 9484 were without OCD (17.12% positive for toxoplasmosis). The estimation of the random effect model indicated a significant common OR of 1.96 [95% CI: 1.32-2.90]. Conclusion This systematic review and meta-analysis revealed that toxoplasmosis could be as an associated factor for OCD (OR = 1.96). However, further prospective investigations are highly recommended to illuminate the underlying pathophysiological mechanisms of T. gondii infection in OCD and to better investigate the relationship between OCD and T. gondii infection. Author summary Toxoplasma gondii (T. gondii) is an obligate neurotropic parasite that infected about 25-30% of the total human population in the developed and developing countries. The obsessive compulsive disorder (OCD) is a psychiatric disease that affects the income and quality of life. Some studies confirmed an association between infectious agents as the associated or protective factors specifying the development of psychiatry diseases. Among various pathogens associated with psychological disorders, most of the attention is on T. gondii, which has a life-long asymptomatic latent phase after a short acute stage in healthy individuals. The detrimental effect of T. gondii on immunocompromised people and pregnant women is an important concern for public health. The correlation between toxoplasmosis and OCD is still relatively understudied with a paucity of documented findings. The previous meta-analysis reviewed only two studies and reported a 3.4-fold greater chance of OCD. The results of our study presented stronger evidence of a positive relationship between toxoplasmosis and OCD. Eventually, our research team hopes to present an overview of what is known and encourage more intensive research to determine the real impact of this parasite on the occurrence of OCD that may contribute to the prevention of OCD worldwid

Strategies developed by Toxoplasma gondii to survive in the host

January 31, 2020
Zhu, W. B., Li, J. Y., Pappoe, F., Shen, J. L., Yu, L.
Frontiers in Microbiology 2019, 10

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The relationship between obsessive compulsive disorder and Toxoplasma gondii : a systematic review and metaanalysis

November 20, 2018
Daryani Ahmad, N. C. T., Sharif Mehdi, Sarvi Shahabeddin, Moosazadeh Mahmood, A., Aghayan Sargis, Gholami Shirzad, Hosseininejad Zahra, Amouei Afsaneh
PROSPERO 2018

Toxoplasmosis seroprevalence in rheumatoid arthritis patients: A systematic review and meta-analysis

August 31, 2018
Hosseininejad, Z., Sharif, M., Sarvi, S., Amouei, A., Hosseini, S. A., Chegeni, T. N., Anvari, D., Saberi, R., Gohardehi, S., Mizani, A., Sadeghi, M., Daryani, A.
Plos Neglected Tropical Diseases 2018; 12

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The microbiome in psychology and cognitive neuroscience

February 12, 2018
Sarkar, A. , Harty, S., Lehto,S. M., Moeller, A. H. , Dinan, T. G. , Dunbar,R. I. M. , Cryan, J. F. ,Burnet, P. W. J.
Trends in Cognitive Sciences 2018; 22: 611-636

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

February 12, 2018
Martinez, V. O. , Lima, F. W. D., . de Carvalho, C. F, Menezes, J. A.
Parasitology Research 2018; 117: 3059-3065

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The potential risk of toxoplasmosis for traffic accidents: A systematic review and meta-analysis

February 12, 2018
Gohardehi, S. , Sharif, M. , Sarvi, S., Moosazadeh, M., Alizadeh-Navaei,R., Hosseini,S. A., Amouei,A. , Pagheh, A. , Sadeghi , M., Daryani, A.
Experimental Parasitology 2018; 191: 19-24

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Toxoplasmosis, the insidious parasitic infection: dangers of asymptomatic carrier state

December 8, 2017
Bognar, L., Izso, T., Szakos, D., Kasza, G.
Magyar Allatorvosok Lapja 2017;139:479-487

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Background: The highly prevalent parasitic infection of humans, toxoplasmosis, can have serious consequences even during an asymptomatic course of the disease. The causative agente of infection is Toxoplasma gondii, which proliferates in the intestine of cats. Risk of infection by direct contact with cats is low, but the infection can occur due to contaminated soil, water, unwashed vegetables and fruits, as well as insufficiently heat-treated meat. Objectives: The aim of this study was to synthesize the current knowledge about infection caused by Toxoplasma gondii in a brief review focusing on latent toxoplasmosis in humans. Materials and Methods: More than hundred articles, studies and reports from scientific journals were considered to summarize the infection's characteristics such as prevalence and symptoms in humans. Results and Discussion: The symptoms of acute toxoplasmosis are either featureless, or non-existent, although, for people with immunosuppression it can be fatal, and for expectants it can result in foetal harm. The detection of the infection is conducted with serology methods, however, only in a few European countries are general screenings present. The asymptomatic carrier state is dangerous as well, because the cysts subsist in the brain of the host, which affects behaviour, the regulation of emotions, and also the level of several hormones. The latent toxoplasmosis can be connected to aggression, anxiety, schizophrenia, bipolar personality disorder, suicidal inclination, depression, and the reduction in intelligence quotient. For the reason of the deterioration of reaction time, the disease increases the risk of traffic accidents. The latent toxoplasmosis also influences personality traits; for women and men the alteration of the personality change differs. There is no data on the current epidemiological situation in Hungary, and not even in Europe. A research regarding the extent of asymptomatic carrier state and about the psychological changes in the Hungarian population has not been conducted so far.

Sixty years (1957-2017) of research on toxoplasmosis in China-An overview

October 30, 2017
Pan, M., Lyu, C., Zhao, J., Shen, B.
Frontiers in Microbiology 2017; 8: 1825

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

October 2, 2017
de Barros, Jlvm, Barbosa, I. G., Salem, H., Rocha, N. P., Kummer, A., Okusaga, O. O., Soares, J. C., Teixeira, A. L.
Journal of Affective Disorders 2017; 209: 59-65

Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses

May 11, 2017
Bortolato, B., Kohler, C.A., Evangelou, E., Leon-Caballero, J., Solmi, M., Stubbs, B., Belbasis, L., Pacchiarotti, I., Kessing, L.V., Berk, M., Vieta, E., Carvalho, A.F.
Bipolar Disorder 2017; 19: 84-96

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Relationship between toxoplasmosis and schizophrenia: A review

May 4, 2017
Fuglewicz, A.J., Piotrowski, P., Stodolak, A.,
Advances in Clinical and Experimental Medicine 2017;26: 1031-1036

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Is chronic toxoplasmosis a risk factor for diabetes mellitus? A systematic review and meta-analysis of case-control studies

October 6, 2016
Majidiani, H., Datuand, S., Daryani, A., Galuan-Ramirez, M. D., Foroutan-Rad, M.
Brazilian Journal of Infectious Diseases 2016; 20: 605-609.

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Exposure to perinatal infections and bipolar disorder: A systematic review

May 24, 2016
Barichello, T., Badawy, M., Pitcher, M. R., Saigal, P., Generoso, J. S., Goularte, J. A., Simoes, L. R., Quevedo, J., Carvalho, A. F.
Curr Mol Med 2016; 16: 106-118

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Meta-analysis of anti-Toxoplasma gondii IgM antibodies in acute psychosis

October 6, 2015
Monroe, J.M., Buckley ,P.F., Miller, B.J.
Schizophrenia Bulletin 2015; 41: 989-998

Toxoplasmosis and epilepsy – systematic review and meta analysis

October 6, 2015
Ngoungou, E. B., Bhalla, D., Nzoghe, A., Darde, M. L., Preux, P. M.
PLoS Neglected Tropical Diseases 2015; 9

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

October 6, 2015
Sutterland, A. L., Fond, G., Kuin, A., Koeter, M. W. J., Lutter, R., van Gool, T., Yolken, R., Szoke, A., Leboyer, M., de Haan, L.
Acta Psychiatrica Scandinavica 2015; 132: 161-179.

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Neurological and neuropsychiatric consequences of chronic Toxoplasma infection

September 27, 2015
Flegr, J.
Clinical Microbiology Reports 2015; 2(4). DOI 10.1007/s40588-015-0024-0

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Schizophrenia and Toxoplasma gondii: an undervalued association?

September 27, 2015
Flegr, J.
Expert Review of Anti-infective Therapy 2015; 13: 817-820

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Transdiagnostic exploration of the association of Toxoplasma gondii with psychiatric disorders. A systematic review and meta analysis

May 29, 2015
Sutterland, A., Fond, G., Kuin, A., Koeter, M., Lutter, R., Van Gool, T., Yolken, R., Szoke, A., Leboyer, M., De Haan, L.
European Psychiatry 2015; 30: Doi 10.1016/S0924-9338(15)30059-6

Association between prenatal exposure to maternal infection and offspring mood disorders: A review of the literature

May 25, 2015
Simanek, A. M., Meier, H. C. S.
Current Problems in Pediatric and Adolescent Health Care 2015; 45: 325-364

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The “psychomicrobiotic”: Targeting microbiota in major psychiatric disorders: A systematic review

January 9, 2015
Fond, G., Boukouaci, W., Chevalier, G., Regnault, A., Eberl, G., Hamdani, N., Dickerson, F., Macgregor, A., Boyer, L., Dargel, A., Oliveira, J., Tamouza, R., Leboyer, M.
Pathologie Biologie 2015; 63: 35-42

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

January 9, 2015
Gutierrez-Fernandez, J., del Castillo, J. D. D., Mananes-Gonzalez, S., Carrillo-Avila, J. A., Gutierrez, B., Cervilla, J. A., Sorlozano-Puerto, A.
Neuropsychiatric Disease and Treatment 2015;11: 843-852

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Transdiagnostic exploration of the association of Toxoplasma gondii with psychiatric disorders: a systematic review and meta-analysis

October 9, 2014
Sutterland, A., Fond, G., Kuin, A., Koeter, M. Lutter, R., van Gool, T., Yolken, R., Szoke, A., Leboyer, M., de Haan, L.
Early Intervention in Psychiatry 2014; 8: 12-12

Toxoplasmosis can be a sexually transmitted infection with serious clinical consequences. Not all routes of infection are created equal

September 27, 2014
Flegr, J., Klapilova, K., Kankova, Š.
Medical Hypotheses 2014; 83: 286–289, 2014

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Toxoplasma gondii infects about 30% of the human population. Common sources of infection are oocysts in cat faeces contaminating drinking water or unwashed vegetables, undercooked meat containing tissue cysts, and organ transplants from infected donors containing tissue cysts. However, very often, it is not possible to identify any potential source of infection in mothers of children with congenital toxoplasmo- sis. Here we present a hypothesis suggesting that toxoplasmosis is transmitted from infected men to non- infected women during unprotected sexual intercourse, which can result in the most serious form of disease, congenital toxoplasmosis. Arguments for the hypothesis: (1) Toxoplasma tachyzoites are present in the seminal fluid and tissue of the testes of various animals including humans. In some species infec- tion of females by artificial insemination with semen from infected males has been observed. (2) Up to two thirds of Toxoplasma infections in pregnant women cannot be explained by the known risk factors. (3) Prevalence of toxoplasmosis in women in child-bearing age covaries with the incidence of sexually transmitted diseases in particular countries. (4) In some countries, an increased incidence of toxoplasmo- sis has been reported in women (but not men) aged 25–35 years. This second peak of infection could be associated with women having regular unprotected sex after marriage. (5) Toxoplasmosis triggers schizo- phrenia in predisposed subjects. Onset of schizophrenia is about 2–3 years earlier in men than in women. However, this difference in the onset can be found only between Toxoplasma -infected patients. The increased onset of schizophrenia in infected women could be associated with the already mentioned sec- ond peak of toxoplasmosis incidence. (6) The prevalence of toxoplasmosis decreases in developed coun- tries in last 20 years. This trend could be a result of decrease in promiscuity and increase in safe sex practices, both associated with the AIDS pandemics. (7) In women, probability of being Toxoplasma - infected correlates positively with the amount of unprotected sex with the child’s father before the con- ception. Evidence against the hypothesis: Questionnaire study showed negative association between Tox- oplasma infection and the number of earlier partners with whom the woman had unprotected sex. If our hypothesis turns out to be true, then sexual route of transmission, even if rare, could be responsible for a large part of cases of congenital toxoplasmosis. Women should be warned that having unprotected sex with men of positive or unknown toxoplasmosis status should be avoided during pregnancy.

Prenatal maternal infection, neurodevelopment and adult schizophrenia: a systematic review of population-based studies

October 11, 2013
Khandaker, G. M., Zimbron, J., Lewis, G., Jones, P. B.
Psychological Medicine 2013; 43: 239-257

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Toxoplasma oocysts as a public health problem

October 9, 2013
Torrey, E.F., Yolken, R.H.
Trends in Parasitology 2013; 29: 380-384

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How and why Toxoplasma makes us crazy

September 27, 2013
Flegr, J.
Trends in Parasitology, 29, 156-163. doi: 10.1016/j.pt.2013.01.007. ,2013

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Influence of latent Toxoplasma infection on human personality, physiology and morphology: pros and cons of the Toxoplasma-human model in studying the manipulation hypothesis

September 27, 2013
Flegr, J.
Journal of Experimental Biology 2013; 216: 127-133

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The parasitic protozoan Toxoplasma gondii infects about one-third of the population of developed countries. The life-long presence of dormant stages of this parasite in the brain and muscular tissues of infected humans is usually considered asymptomatic from the clinical point of view. In the past 20  years, research performed mostly on military personnel, university students, pregnant women and blood donors has shown that this ʻ asymptomatic ʼ disease has a large influence on various aspects of human life. Toxoplasma -infected subjects differ from uninfected controls in the personality profile estimated with two versions of Cattell ʼ s 16PF, Cloninger ʼ s TCI and Big Five questionnaires. Most of these differences increase with the length of time since the onset of infection, suggesting that Toxoplasma influences human personality rather than human personality influencing the probability of infection. Toxoplasmosis increases the reaction time of infected subjects, which can explain the increased probability of traffic accidents in infected subjects reported in three retrospective and one very large prospective case-contr ol study. Latent toxoplasmosis is associated with immunosuppression, which might explain the increased probability of giving birth to a boy in Toxoplasma- infected women and also the extremely high prevalence of toxoplasmosis in mothers of children with Down syndrome. Toxoplasma -infected male students are about 3  cm taller than Toxoplasma- free subjects and their faces are rated by women as more masculine and dominant. These differences may be caused by an increased concentration of testosterone. Toxoplasma also appears to be involved in the initiation of more severe forms of schizophrenia. At least 40 studies confirmed an increased prevalence of toxoplasmosis among schizophrenic patients. Toxoplasma- infected schizophrenic patients differ from Toxoplasma- free schizophrenic patients by brain anatomy and by a higher intensity of the positive symptoms of the disease. Finally, five independent studies performed in blood donors, pregnant women and military personnel showed that RhD blood group positivity, especially in RhD heterozygotes, protects infected subjects against various effects of latent toxoplasmosis, such as the prolongation of reaction times, an increased risk of traffic accidents and excessive pregnancy weigh t gain. The modern human is not a natural host of Toxoplasma . Therefore, it can only be speculated which of the observed effects of latent toxoplasmosis are the result of the manipulation activity of the Toxoplasma aimed to increase the probability of its transmission from a natural intermediate to the definitive host by predation, and which are just side effects of chronic infection