Relationship Between Mental Disorder and Chronic Toxoplasmosis in Iranian Soldiers


Kamran Anoshirvani 1 , Alireza Khoshdel 2 , Zahra Sadat Asadi ORCID 3 , Parviz Dabaghi 4 , Mohammad Emdadi Rad 1 , Minoo Shaddel ORCID 1 , *

1 Department of Parasitology and Mycology, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran

2 Department of Public Health, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran

3 Department of Community Medicine and Millitary Epidemiology Research Centre, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran

4 Department of Clinical Psychology, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran

How to Cite: Anoshirvani K , Khoshdel A, Asadi Z S, Dabaghi P, Emdadi Rad M , et al. Relationship Between Mental Disorder and Chronic Toxoplasmosis in Iranian Soldiers, Ann Mil Health Sci Res. 2019 ; 17(4):e100219. doi: 10.5812/amh.100219.


Annals of Military and Health Sciences Research: 17 (4); e100219
Published Online: December 22, 2019
Article Type: Research Article
Received: December 16, 2019
Accepted: December 16, 2019


Background: Toxoplasmosis, with worldwide distribution, may have tissue cyst in a different organ such the brain. The mental disorder associated with toxoplasmosis among soldiers has been poorly studied.

Objectives: The purpose of this study was to investigate mental disorders among soldiers with chronic toxoplasmosis.

Methods: A total of 239 soldier’s blood samples from one of the garrison in Tehran, Iran, were collected and sera were detected for IgG against T. gondii using the ELISA technique.

Results: Of all examined, sera 69 (28.87%) were positive, who were interpreted as the chronic toxoplasmosis. There was no significant association between mental disorders and chronic toxoplasmosis. The positive chronic toxoplasmosis was significantly higher in the consumption of unpasteurized milk, undercooked meat, and juicy and soil-related occupations.

Conclusions: It seems that the immune system may control the parasite completely and prevalence of chronic toxoplasmosis was high in the region.

Copyright © 2019, Annals of Military and Health Sciences Research. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

1. Background

Toxoplasma gondii is an intracellular protozoan that causes toxoplasmosis disease, which is a worldwide infection and has approximately infected one-third of the world’s population (1, 2). In humans, infection with this parasite is known as a risk factor for the development of schizophrenia and depression (3-6). The prevalence of toxoplasmosis is varied from 8.2% to 63.2% and 11.0% to 80% in Europe and American, respectively (7).

The prevalence of infection in different regions of Iran is varied based on weather conditions. Environmental conditions, such as the changes in humidity and temperature have a direct effect in maintaining sporulation of oocysts excreted by the final host cat (1). Studies in different regions in Iran show that the seroprevalence of T. gondii infection was at 39.3% among the general population (8).

The number of parasites, parasite virulence, genetic background, sex, and immunological status of individuals seem to affect the progression of the infection. Toxoplasmosis has two acute and chronic forms (9). The chronic form is seen in people who seem to be healthy (1). Typically, in people with an effective immune system, toxoplasmosis is a benign infection and does not cause a specific problem (2). The parasite develops cysts in various organs, including different anatomical places of the brain and various types of neurons. Consequently, the infection can cause various hormonal and mental disorders and probably some personality and behavioral changes (1, 6, 10) like obsessive-compulsive disorder, suicide, Alzheimer’s, Parkinson’s disease, epilepsy, migraine headaches, mental retardation, and behavioral and neurological disorders (3-6).

Previous studies have shown the relationship between toxoplasmosis and the phenomenon of anxiety and depression (5, 6).

2. Objectives

One of the most important pillars of human health is mental health, which is an aspect of the general concept of health. Since the study of the most common psychiatric disorders in soldiers with chronic toxoplasmosis has not been done yet, the aim of this study was to investigate the most common mental disorders in soldiers with chronic toxoplasmosis.

3. Methods

3.1. Study Design

In a cross-sectional study, a total of 239 blood samples were taken from the voluntary soldiers in one of the garrison in Tehran, Iran. Then, the MMPI-short form 71 questionnaires were filled by them.

3.2. Laboratory Tests

The blood samples were centrifuged (2000× g, 10 min) and the serum was separated and stored at -70ºC. Then, the serums were analyzed for anti-Toxoplasma gondii IgG antibodies using ELISA (Capitia TM. T.gondii (Toxo) IgG Capita TM) kits). IgG antibodies against T. gondii levels of > 1/1 UL/mL were considered to be seropositive. A positive IgG test was interpreted as chronic toxoplasmosis.

3.3. MMPI Tests

Then, seropositive and seronegative groups were defined and these two groups were compared for mental health using MMPI-short form 71 test. Depression, anxiety, and six other mental disorders were evaluated by this general mental health test.

3.4. Validity and Reliability of the Questionnaire

The validity and reliability of the MMPI questionnaire were measured in the different studies in Iran and around the world (11). In the current study, the alpha Cronbach’s coefficient of the hypochondria, depression, hysteria, psychopathic deviation, paranoia, psychasteria, schizophrenia, and mania were: 0.80,0.70, 0.85, 0.77, 0.87, 0.79, 0.82, and 0.71, respectively, and 0.78 totally.

3.5. Statistical Analysis

Kolmogorov-Smirnov test was used to check the normality of the data. Regarding the non-normalization of the data, the Mann-Whitney test was used for comparison the mean of score in mental disorders, and the chi-square test was used for analyzing the pattern of diet between groups. The significance level was considered to be P < 0.05. Analyses were performed using SPSS software version 16 (SPSS Inc., Chicago, IL, USA).

4. Results

A total of 69 (28.87%) out of 239 samples were seropositive. The seropositive was significantly higher in the ones who consumed unpasteurized milk, undercooked meat (juicy), and contacted with soil (Table 1) (using chi-square test, P < 0.05).

Table 1. Percentage of Seropositive Cases in Terms of the History of Occupational Contact with the Soil, How to Use Meat, and Milk
SerumIWOHOCSIWHOCSCooked MeatUndercooked MeatUnpasteurized MilkPasteurized Milk
Seropositive 69 (28.87%)
Seronegative 170 (71.13%)99.40.660.040.038.461.6

Abbreviations: IWHOCS, individuals with a history of occupational contact with the soil; IWOHOCS, individuals without a history of occupational contact with the soil

The MMPI-short form 71 test revealed that the mental disorders were not significantly different between the seropositive and seronegative groups (Table 2).

Table 2. Comparison of Different Mean of Indicators in Seropositive and Seronegative Groups
Groups, IndicatorSeropositive, Mean ± SDSeronegative, Mean ± SDP Value
Perfectionism and lying2.89 ± 1.442.87 ± 1.430.66
Mental disturbance and sense of cooperation2.46 ± 1.652.51 ± 1.850.26
Defense mechanism and security feeling9.99 ± 2.989.98 ± 2.860.83
Psychopathic deviation6.06 ± 2.66.08 ± 2.460.77
Hypochondria5.36 ± 2.35.36 ± 2.410.96
Paranoia4.99 ± 2.014.95 ± 1.980.72
Hysteria12.45 ± 3.6512.37 ± 3.400.61
Mania3.5 ± 1.983.47 ± 2.210.96
Psychasthenia5.47 ± 3.102.14 ± 3.280.68
Depression8.2 ± 3.183.26 ± 3.160.3
Schizophrenia6.37 ± 2.923.17 ± 3.250.82

5. Discussion

Toxoplasmosis have been hypothesized to be the etiology of some mental disorders. The effect of the toxoplasmosis on human personality, physiology, and morphology were assessed using the personality questionnaire and there was a significant difference between personality traumatized men and women (12); it is not consistent with the outcome of this study. As the questionnaire, the age, and sex of subjects are different in the current study, perhaps, these factors affected to obtain the different outcome.

The relationship between toxoplasmosis and schizophrenia, the proposed mechanisms of the pathogenesis of schizophrenia, the simultaneous participation of genetic, and infectious and environmental factors that cause brain growth and differentiation were assessed and recorded, which is capable of affecting some of the metabolic and coagulation pathways led to the development of the disease disorder (13). This result is not consistent with the present study and maybe, the involvement of other organs in seropositive cases (apart from brain) happened in the current study (10). According to the other studies, the involvement of the nervous system or brain in chronic toxoplasmosis occurred in the upper and middle ages more, consequently, neurological symptoms will appear more in older individuals. In the other words, as age increases, the likelihood of behavioral disorders increases (14, 15). Since the age of the soldiers in the current study were between 18 to 25 years old, it is supposed that the immune system could still suppress and control the parasite, and the neuritis has not taken place yet, or due to the gradual progression, symptoms has not been observed yet (14-16).

Another study recorded that chronic toxoplasmosis was significantly higher in patients with schizophrenia than in healthy ones; it disagreed on the result of the current study. It seems that the different outcome between two studies might be due to the different subjects of them. The study tried to detect the chronic toxoplasmosis in schizophrenic patients as a subject, however, in the present study, on the contrary, mental disorders were looked for in ones with chronic toxoplasmosis as subjects (6).

In the present study, 69 (28.8%) soldiers were seropositive, which was confirmed by some studies (17). According to the results of this study, how the meat and milk were consumed, and lack of hygiene in contact with the soil were the important ways to transmit the toxoplasmosis and should be of more concern.

5.1. Conclusions

Overall, the soldiers with chronic toxoplasmosis, as a young community, showed no significant mental disorders and similar research in older groups or females is suggested. There were chronic toxoplasmosis in soldiers and the prevalence of toxoplasmosis, especially chronic form was high. Therefore, the infection of toxoplasmosis should be considered. The strength of this study was the group that was considered (soldiers). In terms of their behavior, the results help us know which parts they should be employed in during their military service. The limitation of this study was “the lack of knowledge about the locality of tissue cysts in the body of ones with chronic toxoplasmosis”. If the brain was involved, the mental disorders would be followed better.




  • 1.

    Dalimi A, Abdoli A. Latent toxoplasmosis and human. Iran J Parasitol. 2012;7(1):1.

  • 2.

    Shaddel M, Mirzaii Dizgah I, Sharif F. The prevalence of toxoplasmosis in Imam Reza Hospital blood bank samples, Tehran, Iran. Transfus Apher Sci. 2014;51(2):181-3. doi: 10.1016/j.transci.2014.08.017. [PubMed: 25219635].

  • 3.

    Hinze-Selch D, Daubener W, Erdag S, Wilms S. The diagnosis of a personality disorder increases the likelihood for seropositivity to Toxoplasma gondii in psychiatric patients. Folia Parasitol (Praha). 2010;57(2):129-35. doi: 10.14411/fp.2010.016. [PubMed: 20608475].

  • 4.

    Arling TA, Yolken RH, Lapidus M, Langenberg P, Dickerson FB, Zimmerman SA, et al. Toxoplasma gondii antibody titers and history of suicide attempts in patients with recurrent mood disorders. J Nerv Ment Dis. 2009;197(12):905-8. doi: 10.1097/NMD.0b013e3181c29a23. [PubMed: 20010026].

  • 5.

    Henriquez SA, Brett R, Alexander J, Pratt J, Roberts CW. Neuropsychiatric disease and Toxoplasma gondii infection. Neuroimmunomodulation. 2009;16(2):122-33. doi: 10.1159/000180267. [PubMed: 19212132].

  • 6.

    Alipour A, Shojaee S, Mohebali M, Tehranidoost M, Abdi Masoleh F, Keshavarz H. Toxoplasma infection in schizophrenia patients: A comparative study with control group. Iran J Parasitol. 2011;6(2):31-7. [PubMed: 22347285]. [PubMed Central: PMC3279881].

  • 7.

    Passos ADC, Bollela VR, Furtado JMF, Lucena MM, Bellissimo-Rodrigues F, Paula JS, et al. Prevalence and risk factors of toxoplasmosis among adults in a small Brazilian city. Rev Soc Bras Med Trop. 2018;51(6):781-7. doi: 10.1590/0037-8682-0214-2017. [PubMed: 30517531].

  • 8.

    Khalili M, Mahami-Oskouei M, Shahbazi A, Safaiyan A, Mohammadzadeh-Gheshlaghi N, Mahami-Oskouei L. The correlation between serum levels of anti-Toxoplasma gondii antibodies and the risk of diabetes. Iran J Parasitol. 2018;13(4):637-42. [PubMed: 30697319]. [PubMed Central: PMC6348218].

  • 9.

    Shaddel M, Mehbod ASA, Karamy M. Toxoplasma gondii infection in neonates. Iran J Parasitol. 2007;2(3):34-7.

  • 10.

    Zareian P, Mirzaii Dizgah I, Shaddel M, Khodabandehloo F. Effects of Toxoplasma gondii infection on anxiety, depression and ghrelin level in male rats. J Parasit Dis. 2016;40(3):688-93. doi: 10.1007/s12639-014-0561-0. [PubMed: 27605768]. [PubMed Central: PMC4996174].

  • 11.

    Colligan RC, Osborne D, Swenson WM, Offord KP. The MMPI: Development of contemporary norms. J Clin Psychol. 1984;40(1):100-7. doi: 10.1002/1097-4679(198401)40:1<100::aid-jclp2270400118>;2-g.

  • 12.

    Flegr J. Influence of latent Toxoplasma infection on human personality, physiology and morphology: Pros and cons of the Toxoplasma-human model in studying the manipulation hypothesis. J Exp Biol. 2013;216(Pt 1):127-33. doi: 10.1242/jeb.073635. [PubMed: 23225875].

  • 13.

    Fuglewicz AJ, Piotrowski P, Stodolak A. Relationship between toxoplasmosis and schizophrenia: A review. Adv Clin Exp Med. 2017;26(6):1031-6. doi: 10.17219/acem/61435. [PubMed: 29068607].

  • 14.

    Pearce BD, Hubbard S, Rivera HN, Wilkins PP, Fisch MC, Hopkins MH, et al. Toxoplasma gondii exposure affects neural processing speed as measured by acoustic startle latency in schizophrenia and controls. Schizophr Res. 2013;150(1):258-61. doi: 10.1016/j.schres.2013.07.028. [PubMed: 23953218]. [PubMed Central: PMC3786776].

  • 15.

    Ling VJ, Lester D, Mortensen PB, Langenberg PW, Postolache TT. Toxoplasma gondii seropositivity and suicide rates in women. J Nerv Ment Dis. 2011;199(7):440-4. doi: 10.1097/NMD.0b013e318221416e. [PubMed: 21716055]. [PubMed Central: PMC3128543].

  • 16.

    Bhadra R, Cobb DA, Weiss LM, Khan IA. Psychiatric disorders in toxoplasma seropositive patients--the CD8 connection. Schizophr Bull. 2013;39(3):485-9. doi: 10.1093/schbul/sbt006. [PubMed: 23427221]. [PubMed Central: PMC3627775].

  • 17.

    Kolbekova P, Kourbatova E, Novotna 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(10):1012-7. doi: 10.1111/j.1469-0691.2007.01771.x. [PubMed: 17617185].