Skip to main content Accessibility help

Toxoplasma-Infected Subjects Report an Obsessive-Compulsive Disorder Diagnosis More Often and Score Higher in Obsessive-Compulsive Inventory

  • J. Flegr (a1) (a2) and J. Horáček (a2)



Latent toxoplasmosis, the life-long presence of dormant stages of Toxoplasma in immunoprivileged organs and of anamnestic IgG antibodies in blood, affects about 30% of humans. Infected subjects have an increased incidence of various disorders, including schizophrenia. Several studies, as well as the character of toxoplasmosis-associated disturbance of neurotransmitters, suggest that toxoplasmosis could also play an etiological role in Obsessive-Compulsive Disorder (OCD).


The aim of the present cross-sectional study performed on a population of 7471 volunteers was to confirm the association between toxoplasmosis and OCD, and toxoplasmosis and psychological symptoms of OCD estimated by the standard Obsessive-Compulsive Inventory-Revised (OCI-R).


Incidence of OCD was 2.18% (n = 39) in men and 2.28% (n = 83) in women. Subjects with toxoplasmosis had about a 2.5 times higher odds of OCD and about a 2.7 times higher odds of learning disabilities. The incidence of 18 other neuropsychiatric disorders did not differ between Toxoplasma-infected and Toxoplasma-free subjects. The infected subjects, even the OCD-free subjects, scored higher on the OCI-R.

Limitations: Examined subjects provided the information about their toxoplasmosis and OCD statuses themselves, which could result in underrating the strength of observed associations.


The results confirmed earlier reports of the association between toxoplasmosis and OCD. They also support recent claims that latent toxoplasmosis is in fact a serious disease with many impacts on quality of life of patients.


Corresponding author

*Corresponding author at: Division of Biology, Faculty of Science, Charles University, Vinicna 7, CZ-128 44 Prague, Czech Republic. E-mail (J. Flegr).


Hide All
[1]Tenter, A.M.Heckeroth, A.R.Weiss, L.M.Toxoplasma gondii: from animals to humans. Int J Parasitol 2000; 30: 12171258
[2]Flegr, J.Prandota, J.Sovickova, M.Israili, Z.H.Toxoplasmosis – a global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries. PLoS ONE 9 2014
[3]Prandota, J.Metabolic, immune, epigenetic, endocrine and phenotypic abnormalities found in individuals with autism spectrum disorders, Down syndrome and Alzheimer disease may be caused by congenital and/or acquired chronic cerebral toxoplasmosis. Res Autism Spectr Disord 2011; 5: 1459
[4]Torrey, E.F.Bartko, J.J.Yolken, R.H.Toxoplasma gondii and other risk factors for schizophrenia: an update. Schizophr Bull 2012; 38: 642647
[5]Flegr, J.How and why Toxoplasma makes us crazy. Trends Parasitol 2013; 29: 156163
[6]Sutterland, A.L.Fond, G.Kuin, A.Koeter, M.W.Lutter, R.van Gool, al.Beyond the association. Toxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta-analysis. Acta Psychiatr Scand 2015; 132: 16117910.1111/acps.12423
[7]Niebuhr, D.W.Cowan, D.N.Millikan, A.M.Yolken, R.Li, Y.Weber, N.Risk of schizophrenia and antibodies to Toxoplasma gondii among U.S. military personnel. Schizophr Bull 2007; 33: 243244
[8]Gaskell, E.A.Smith, J.E.Pinney, J.W.Westhead, D.R.McConkey, G.A.A unique dual activity amino acid hydroxylase in Toxoplasma gondii. PLoS ONE 4 2009 e4801
[9]Prandovszky, E.Gaskell, E.Martin, H.Dubey, J.P.Webster, J.P.McConkey, G.A.The neurotropic parasite Toxoplasma gondii increases dopamine metabolism. PLoS ONE 6 2011 e2386610.1371/journal.pone.0023866
[10]Martin, H.L.Alsaady, I.Howell, G.Prandovszky, E.Peers, C.Robinson, al.Effect of parasitic infection on dopamine biosznthesis in dopaminergic cells. Neuroscience 2015; 306: 506210.1016/j.neuroscience.2015.08.005
[11]Westenberg, H.G.M.Fineberg, N.A.Denys, D.Neurobiology of obsessive-compulsive disorder: serotonin and beyond. CNS Spectr 2007; 12: 1427
[12]Wittchen, H.U.Jacobi, F.Rehm, J.Gustavsson, A.Svensson, M.Jonsson, al.The size and burden of mental disorders and other disorders of the brain in Europe 2010. Eur Neuropsychopharmacol 2011; 21: 655679
[13]Stein, D.J.Obsessive-compulsive disorder. Lancet 2002; 360: 397405
[14]Miman, O.Mutlu, E.A.Ozcan, O.Atambay, M.Karlidag, R.Unal, S.Is there any role of Toxoplasma gondii in the etiology of obsessive-compulsive disorder?. Psychiatry Res 2010; 177: 263265
[15]Cong, W.Dong, W.Bai, L.Wang, X.Y.Ni, X.T.Qian, al.Seroprevalence and associated risk factors of Toxoplasma gondii infection in psychiatric patients: a case–control study in eastern China. Epidemiol Infect 2015; 143: 31033109
[16]Flegr, J.Neurological and neuropsychiatric consequences of chronic Toxoplasma infection. Parasitology 2015; 2: 163172
[17]Kankova, S.Flegr, J.Calda, P.The influence of latent toxoplasmosis on women’s reproductive function: four cross-sectional studies. Folia Parasitol 2015 62
[18]Villard, O.Cimon, B.L’Ollivier, C.Fricker-Hidalgo, H.Godineau, N.Houze, al.Serological diagnosis of Toxoplasma gondii infection recommendations from the French National Reference Center for Toxoplasmosis. Diagn Microbiol Infect Dis 2016; 84: 223310.1016/j.diagmicrobio.2015.09.009
[19]Foa, E.B.Huppert, J.D.Leiberg, S.Langner, R.Kichic, R.Hajcak, al.The obsessive-compulsive inventory: development and validation of a short version. Psychol Assess 2002; 14: 485496
[20]Flegr, J.Novotná, M.Fialová, A.Kolbeková, P.Gašová, Z.The influence of RhD phenotype on toxoplasmosis- and age-associated changes in personality profile of blood donors. Folia Parasitol 2010; 57: 14315010.14411/fp.2010.018
[21]van Grootheest, D.S.Cath, D.C.Beekman, A.T.Boomsma, D.I.Twin studies on obsessive-compulsive disorder: a review. Twin Res Hum Genet 2005; 8: 450458
[22]Olver, J.S.O’Keefe, G.Jones, G.R.Burrows, G.D.Tochon-Danguy, H.J.Ackermann, al.Dopamine D-1 receptor binding in the anterior cingulate cortex of patients with obsessive-compulsive disorder. Psychiat Res Neuroimaging 2010; 183: 858810.1016/j.pscychresns.2010.04.004
[23]Szechtman, H.Sulis, W.Eilam, D.Quinpirole induces compulsive checking behavior in rats: a potential animal model of obsessive-compulsive disorder (OCD). Behav Neurosci 1998; 112: 14751485
[24]Ducasse, D.Boyer, L.Michel, P.Loundou, A.Macgregor, A.Micoulaud-Franchi, al.D2 and D3 dopamine receptor affinity predicts effectiveness of antipsychotic drugs in obsessive-compulsive disorders: a metaregression analysis. Psychopharmacology (Berl) 2014; 231: 37653770
[25]Wu, M.Hanna, G.L.Rosenberg, D.R.Arnold, P.D.The role of glutamate signaling in the pathogenesis and treatment of obsessive-compulsive disorder. Pharmacol Biochem Behav 2012; 100: 726735
[26]Yucel, M.Wood, S.J.Wellard, R.M.Harrison, B.J.Fornito, A.Pujol, al.Anterior cingulate glutamate-glutamine levels predict symptom severity in women with obsessive-compulsive disorder. Aust N Z J Psychiatry 2008; 42: 467477
[27]Simpson, H.B.Shungu, D.C.Bender, J.Mao, X.L.Xu, X.Y.Slifstein, al.Investigation of cortical glutamate-gutamine and gamma-aminobutyric acid in obsessive-compulsive disorder by proton magnetic resonance spectroscopy. Neuropsychopharmacology 2012; 37: 26842692
[28]Zhu, Y.J.Fan, Q.Han, X.Zhang, H.Y.Chen, J.Wang, al.Decreased thalamic glutamate level in unmedicated adult obsessive-compulsive disorder patients detected by proton magnetic resonance spectroscopy. J Affect Disord 2015; 178: 193200
[29]Bloch, M.H.Wasylink, S.Landeros-Weisenberger, A.Panza, K.E.Billingslea, E.Leckman, al.Effects of ketamine in treatment-refractory obsessive-compulsive disorder. Biol Psychiatry 2012; 72: 964970
[30]Wang, Z.T.Harmon, S.O’Malley, K.L.Sibley, L.D.Reassessment of the role of aromatic amino acid hydroxylases and the effect of infection by Toxoplasma gondii on host dopamine. Infect Immun 2015; 83: 1039104710.1128/IAI.02465-14
[31]Flegr, J.Preiss, M.Klose, J.Havlíček, J.Vitáková, M.Kodym, P.Decreased level of psychobiological factor novelty seeking and lower intelligence in men latently infected with the protozoan parasite Toxoplasma gondii. Dopamine, a missing link between schizophrenia and toxoplasmosis?. Biol Psychol 2003; 63: 253268
[32]Skallová, A.Novotná, M.Kolbeková, P.Gašová, Z.Veselý, V.Flegr, J.Decreased level of novelty seeking in blood donors infected with Toxoplasma. Neuroendocrinol Lett 2005; 26: 480486
[33]Nagineni, C.N.Pardhasaradhi, K.Martins, M.C.Detrick, B.Hooks, J.J.Mechanisms of interferon-induced inhibition of Toxoplasma gondii replication in human retinal pigment epithelial cells. Infect Immun 1996; 64: 41884196
[34]Kessler, M.Terramani, T.Lynch, G.Baudry, M.A glycine site associated with N-methyl-d-aspartic acid receptors – characterization and identification of a new class of antagonists. J Neurochem 1989; 52: 13191328
[35]Eldefrawy, S.R.Boegman, R.J.Jhamandas, K.Beninger, R.J.The neurotoxic actions of quinolinic acid in the central-nervous-system. Can J Physiol Pharmacol 1986; 64: 369375
[36]Lim, A.Kumar, V.Hari Dass, S.A.Vyas, A.Toxoplasma gondii infection enhances testicular steroidogenesis in rats. Mol Ecol 2013; 22: 102110
[37]Flegr, J.Lindová, J.Kodym, P.Sex-dependent toxoplasmosis-associated differences in testosterone concentration in humans. Parasitology 2008; 135: 427431
[38]Holub, D.Flegr, J.Dragomirecka, E.Rodriguez, M.Preiss, M.Novak, al.Differences in onset of disease and severity of psychopathology between toxoplasmosis-related and toxoplasmosis-unrelated schizophrenia. Acta Psychiatr Scand 2013; 127: 227238
[39]Celik, T.Kartalci, S.Aytas, O.Akarsu, G.A.Gozukara, H.Unal, S.Association between latent toxoplasmosis and clinical course of schizophrenia – continuous course of the disease is characteristic for Toxoplasma gondii-infected patients. Folia Parasitol 62 2015
[40]Horacek, J.Flegr, J.Tintera, J.Verebova, K.Spaniel, F.Novak, al.Latent toxoplasmosis reduces gray matter density in schizophrenia but not in controls: voxel-based-morphometry (VBM) study. World J Biol Psychiatry 2012; 13: 501509
[41]Menzies, L.Chamberlain, S.R.Laird, A.R.Thelen, S.M.Sahakian, B.J.Bullmore, E.T.Integrating evidence from neuroimaging and neuropsychological studies of obsessive-compulsive disorder: the orbitofronto-striatal model revisited. Neurosci Biobehav Rev 2008; 32: 525549
[42]Koprivova, J.Horacek, J.Tintera, J.Prasko, J.Raszka, M.Ibrahim, al.Medial frontal and dorsal cortical morphometric abnormalities are related to obsessive-compulsive disorder. Neurosci Lett 2009; 464: 6266
[43]Koprivova, J.Congedo, M.Horacek, J.Prasko, J.Raszka, M.Brunovsky, al.EEG source analysis in obsessive-compulsive disorder. Clin Neurophysiol 2011; 122: 17351743
[44]Koprivova, J.Horacek, J.Raszka, M.Brunovsky, M.Prasko, J.Standardized low-resolution electromagnetic tomography in obsessive-compulsive disorder – a replication study. Neurosci Lett 2013; 548: 185189
[45]Kodym, P.Machala, L.Roháčová, H.Širocká, B.Malý, M.Evaluation of a commercial IgE ELISA in comparison with IgA and IgM ELISAs, IgG avidity assay and complement fixation for the diagnosis of acute toxoplasmosis. Clin Microbiol Infect 2007; 13: 4047
[46]Kolbeková, P.Kourbatova, E.Novotná, M.Kodym, P.Flegr, J.New and old risk-factors for Toxoplasma gondii infection: prospective cross-sectional study among military personnel in the Czech Republic. Clin Microbiol Infect 2007; 13: 10121017


Toxoplasma-Infected Subjects Report an Obsessive-Compulsive Disorder Diagnosis More Often and Score Higher in Obsessive-Compulsive Inventory

  • J. Flegr (a1) (a2) and J. Horáček (a2)


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed

Toxoplasma-Infected Subjects Report an Obsessive-Compulsive Disorder Diagnosis More Often and Score Higher in Obsessive-Compulsive Inventory

  • J. Flegr (a1) (a2) and J. Horáček (a2)
Submit a response


We encountered an error trying to retrieve Comments for this article. Please try again or contact Customer Services


Reply to: Submit a response

Your details

Conflicting interests

Do you have any conflicting interests? *