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Toxoplasma gondii & Human Phenotype

Compendium of Known Effects and Ongoing Research

gender differences

Economic holobiont: Influence of parasites, microbiota and chemosignals on economic behavior

September 3, 2018
Houdek, P.
Frontiers in Behavioral Neuroscience 2018; 12
Click for abstract
The article is a perspective on utilization of microorganisms and chemosignals in studying human economic behavior. Research in biological roots of economic development has already confirmed that parasitic pressure influenced the creation and development of cultural norms and institutions. However, other effects of microorganisms on human groups and individual decision-making and behavior are heavily understudied. The perspective discusses how parasitic infections, sexually transmitted organisms and microbiota (i.e., "human holobiont") could causally influence risk-seeking behavior, impulsivity, social dominance, empathy, political views and gender differences. As a case study, the parasite Toxoplasma gondii and its influence on economic preferences, personal characteristics and human appearance are examined. I also briefly review how chemosignals influence decision-making, particularly in the social preferences domain. I mention some predictions that arise from the paradigm of economic holobiont for the economic science. The conclusion summarizes limitations of the discussed findings and the stated speculations.

Tagged: chemosignaling, decreased level, economics, family ties, fatal attraction, gender differences, gut-brain axis, latent toxoplasmosis, master possible influence, microbiota, novelty seeking, parasites, personality-traits, risk preferences, social preferences, time preferences, Toxoplasma gondii, toxoplasma gondii infection

Behavior

Depressiveness and neuroticism in Bartonella seropositive and seronegative subjects-preregistered case-controls study

September 3, 2018
Flegr, J., Preiss, M., Balatova, P.
Frontiers in Psychiatry 2018; 9
Click for abstract
Several recent studies have demonstrated the association of cat-related injuries with major depression and with depressiveness in the general population. It was suggested that cat-scratch disease, the infection with the bacterium Bartonella henselae, can be responsible for the observed association. However, no direct evidence for the role of the Bartonella infection in this association has been published until now. In this preregistered case-controls study performed on 250 healthy subjects tested earlier for the presence of anti-Toxoplasma IgG antibodies, we searched for the positive association between presence of anamnestic anti-Bartonella IgG antibodies and depressiveness measured with Beck II inventory, depression subscale of neuroticism measured with N-70 questionnaire, and self-reported health problems. We found that that Bartonella seropositivity was positively correlated with Beck depression only in Toxoplasma-seronegative men and negatively correlated with health in Toxoplasma-seronegative women. Bartonella seropositivity expressed protective effects against Toxoplasma seropositivity-associated increased neuroticism in men while Toxoplasma-seropositivity expressed protective effects against Bartonella seropositivity-associated health problems in women. A comparison of the patterns of association of mental and physical health problems with Bartonella seropositivity and with reported cat-related injury suggests that different factor, possibly infection with different pathogen transmitted by cat related-injuries than the B. henselae, is responsible for the observed association of cat related-injuries with depressiveness and major depression. The existence of complex interactions between Bartonella seropositivity, Toxoplasma seropositivity, and sex also suggest that the effect of symbionts on the host's phenotype must by always studied in the context of other infections, and separately for men and women.

Tagged: animal-related injuries, Bartonella, bartonellosis, behavioral-changes, c-reactive protein, cat-scratch disease, depression, depressiveness, gender differences, health, infection, latent toxoplasmosis, major, Toxoplasma, Toxoplasma gondii, toxoplasmosis, women

Mental health

Puppet master: possible influence of the parasite Toxoplasma gondii on managers and employees

October 2, 2017
Houdek, P.
Academy of Management Perspectives 2017; 31: 63-81
Click for abstract
The article reviews recent literature on the effects of host manipulation by the parasite Toxoplasma gondii (prevalent in about a third of the world's population) on perception, cognition, and behavior of humans, and on the changes in their physical appearance and personality characteristics. I argue that the mind-affecting parasite paradigm offers many research opportunities for management sciences, especially for organizational psychology and neuroscience. The article summarizes the parasite's physiological mechanisms of affecting the host; highlights important behavioral effects of the infection in humans; and speculates on the possible impacts on skills and careers of employees and managers, organizational dynamics, intercultural management, and gender work roles. The conclusion shows limitations of the presented speculations and possible directions for future research on Toxoplasma's effect on organizational dynamics.

Tagged: cognitive function, dynamic capabilities, facial structure predicts, gender differences, general mental-ability, job-performance, latent toxoplasmosis, personality changes, positive organizational-behavior, risk factors

BehaviorPersonality

Toxoplasma gondii infection in schizophrenia and associated clinical features

October 6, 2016
Esshili, A., Thabet, S., Jemli, A., Trifa, F., Mechri, A., Zaafrane, F., Gaha, L., Juckel, G., Babba, H., Jrad, B. B. H.
Psychiatry Research 2016; 245: 327-332
Click for abstract
The belief that latent toxoplasmosis is asymptomatic has been questioned, in particular due to the repeated highlighted link between the Toxoplasma gondii infection and an increased incidence of schizophrenia. However, to understand this relationship, the effect of infection with Toxoplasma gondii on the severity of schizophrenia has been poorly studied. Our work focused on comparing the prevalence of Toxoplasma infection between schizophrenic patients and healthy controls, as well as comparing the clinical features and the demographic characteristics between Toxoplasma-seronegative and Toxoplasma-seropositive patients with schizophrenia. The rate of IgG antibody in the schizophrenia patients was 74.8% compared 53.8% in controls. Patients with schizophrenia had a significantly higher mean of serum IgG antibodies to T. gondii compared to controls. The seropositive male patients had a higher age of disease onset, a higher BPRS score, a greater negative PANSS score and a lower GAF score than the seronegative male patients. These results suggest a higher severity of clinical symptoms in the male patients with schizophrenia. This study provides further evidence to the hypothesis that exposure to Toxoplasma may be a risk factor for schizophrenia. Moreover, toxoplasmosis in men with schizophrenia may lead to more severe negative and cognitive symptoms and a less favorable course of schizophrenia.

Tagged: adult, bipolar disorder, bprs, childhood, gaf, gender differences, male gender, metaanalysis, nervous-system infection, onset of schizophrenia, onset schizophrenia, risk, s congenital toxoplasmosis, sans, Schizophrenia, serum igg, sex-differences, Toxoplasma gondii

Mental health

The influence of latent toxoplasmosis on women’s reproductive function: four cross-sectional studies

January 8, 2015
Kankova, S., Flegr, J., Calda, P.
Folia Parasitologica 2015; 62:
Click for abstract
Several studies have investigated the association between infection with Toxoplasma gondii (Nicolle et Manceaux, 1908), pregnancy and fertility, but the results of studies focused on the fertility are rather ambiguous. Here we report results of four new cross-sectional studies. The studies were performed in the General University Hospital, Prague (study A with n = 1 165, and study C with n = 317), in private clinics of the Centre of Reproductive Medicine, Prague (study B with n = 1 016), and in a population of Czech and Slovak volunteers from the Facebook page 'Guinea Pigs' willing to participate in various basic science studies (study D with n = 524). In studies A and B, the clinical records were used to assess the fertility problems, whereas in studies C and D, the women were asked to rate their fertility problems using a six-point scale. Pregnant T. gondii-infected women were older than T. gondii-free women (study A: 33.1 vs 31.2, P < 0.001; study B: 30.6 vs 29.6, P = 0.012) and more often used assisted reproductive technology to conceive (study A: 17.2% vs 12.4%, P = 0.041; study B: 13.4% vs 9.2%, P = 0.317). Pregnant T. gondii-infected primiparous women were older than T. gondii-free primiparas (study A: 31.1 vs 29.5, P < 0.001; study B: 29.7 vs 28.9, P = 0.064) and more often used assisted reproductive technology to conceive (study A: 24.7% vs 14.4%, P = 0.010; study B: 15.9% vs 15.5%, P = 0.888). T. gondii-infected women reported to take a longer time to conceive than T. gondii-free women (P = 0.015). They also claimed to have more fertility problems than T. gondii-free women (P < 0.0001). Our results suggest that 'asymptomatic' latent toxoplasmosis could be a more serious source of fertility problems and health-associated burden than more severe but far rarer congenital toxoplasmosis.

Tagged: age, asymptomatic toxoplasmosis, behavioral-changes, gender differences, gondii, hypothesis, infertility, manipulation hypothesis, mice, Parasite, psychiatric-disorders, Schizophrenia, sex ratio, testosterone, Toxoplasma gondii

Reproduction

Latent Toxoplasmosis gondii: Emerging Evidence for Influences on Neuropsychiatric Disorders

October 16, 2012
Hurley, R. A., Taber, K. H.
Journal of Neuropsychiatry and Clinical Neurosciences 2012; 24: 376-383
Tagged: antibody-titers, behavioral-changes, central-nervous-system, Cerebral toxoplasmosis, gender differences, infected mice, risk factors, suicide attempts, tissue cysts, traffic accidents

Mental health

The relation of cortisol and sex hormone levels to results of psychological, performance, IQ and memory tests in military men and women

January 9, 2012
Flegr, J., Hampl, R., Černochová, D., Preiss, M., Bičíkova, M., Sieger, L., Příplatová, L., Kaňková, S., Klose, J.
Neuroendocrinology Letters 2012; 33: 224-235
Click for abstract
BACKGROUND: Cortisol, along with other hormones of hypothalamo-pituitary-adrenal axis, belongs to one of the main factors influencing psychological and pathognomic factors, intelligence, and memory. METHODS: The aim of our study was to review a large battery of psychological, performance, IQ and memory tests as to their relation with cortisol, testosterone and estrogen levels in groups of 100 men and 93 women who attended the Central Military Hospital in Prague for regular entrance psychological examinations for military personnel. RESULTS: In men, we detected positive correlations between cortisol and emotional lability, and negative correlations with impulsivity, while in women hypochondria and psychopathology were negatively correlated, and aggression measured with the Meili selective memory test had a positive relation to cortisol level. Testosterone correlated positively with emotional liability and negatively with impulsivity in men, and negatively with hypochondria and psychasteny, indirect aggression, irritability and paranoia in women. Estradiol correlated positively with psychopathology in men, and negatively with phobia. It was positively correlated with negativism in women. No clear correlation was observed between the concentration of steroid hormones and psychomotor performance or intelligence. CONCLUSIONS: Concentrations of steroid hormones correlate with results of several psychological tests, the sign and magnitude of these correlations, however, very often differ in military men and women.

Tagged: aggression, bdi, behavior, cortisol, dominance, estrogen, gender differences, hypothesis, intelligence, meili test, memory, miller 2009, n-70, od-1, otis test, personality, personality tests, psychology, questionnaire, responses, stress, supports, testosterone, testosterone concentration, topp, toxoplasmosis, wmt

Cognitive functionsPersonality

Potential immunomodulatory effects of latent toxoplasmosis in humans

January 9, 2011
Flegr, J., Striz, I.
Bmc Infectious Diseases 2011; 11: Artn 274 10.1186/1471-2334-11-274
Click for abstract
Background: About 30% of the population worldwide are infected with the protozoan parasite Toxoplasma gondii. Latent toxoplasmosis has many specific behavioral and physiological effects on the human organism. Modified reactivity of the immune system has been suggested to play a key role in many of these effects. For example, the immunosuppression hypothesis explains the higher probability of the birth of male offspring observed in Toxoplasma-positive humans and mice by the protection of the (more immunogenic) male embryos against abortion. Methods: Here we searched for indices of immunosuppression in Toxoplasma-positive subjects by comparing clinical records of immunology outpatients. Results: Our cohort study showed that the male patients with latent toxoplasmosis had decreased and the Toxoplasma-positive women had increased leukocyte, NK-cell and monocyte counts in comparison with controls. The B-cell counts were reduced in both Toxoplasma-positive men and women. The difference between Toxoplasma-positive and Toxoplasma-negative subjects diminished with the decline of the specific Toxoplasma antibody titre (a proxy for the length of infection), which is consistent with the observed decreasing strength of the effect of latent toxoplasmosis on human reproduction. The prevalence of toxoplasmosis in 128 male patients was unusually low (10.9%) which contrasted with normal prevalence in 312 female patients (23.7%) and in general population Prague (20-30%). Conclusions: Latent toxoplasmosis has immunomodulatory effects in human and probably protects men against some classes of immunopathological diseases. The main limitation of the present study was the absence of the data on the immunoreactivity of immune cells subpopulations. Therefore further studies are needed to search for indices of immunosuppression in human using more specific markers.

Tagged: antibodies, behavioral-changes, communication, gender differences, gondii, hypothesis, mice, sex ratio, testosterone concentration, traffic accidents

Physical health

Pattern of money allocation in experimental games supports the stress hypothesis of gender differences in Toxoplasma gondii-induced behavioural changes

September 26, 2010
Lindová, J., Kubena, A.A., Sturcová, H., Krivohlavá, R., Novotná, M., Rubesová, A., Havlícek, J., Kodym, P. , Flegr, J.
Folia Parasitologica 2010; 57: 136-142
Click for abstract
Latent toxoplasmosis has been previously found to cause behavioural and personality changes in humans, which are specific for each gender. Here we tested the stress hypothesis of these gender differences based on the assumption that latent toxo - plasmosis causes long-term subliminal stress. In line with this hypothesis, the gender difference will appear specifically in situations with interpersonal context because in contrast to the typical individualistic coping style of men, women have a tendency to express elevated prosocial behaviour under stress. Altogether 295 biology students (29/191 females and 27/104 males infected by T. gondii ) played a modified version of the Dictator Game and the Trust Game. As predicted, a gender difference in the effect of latent toxo - plasmosis was found for the measure of reciprocal altruism in the Trust Game ( p = 0.016), but both genders appeared less generous when infected in the Dictator Game modified to minimize social connotation ( p = 0.048).

Tagged: coping, experimental games, gender differences, stress hypothesis, Toxoplasma

BehaviorPersonality

Brief communication: Latent toxoplasmosis and salivary testosterone concentration-important confounding factors in second to fourth digit ratio studies

January 9, 2008
Flegr, J., Lindova, J., Pivonkova, V., Havlicek, J.
American Journal of Physical Anthropology 2008; 137: 479-484
Click for abstract
A sexually dimorphic characteristic, the second to fourth digit ratio (2D:4D ratio), has been shown to reflect the prenatal concentration of sex steroid hormones and to correlate with many personality, physiological, and life history traits. The correlations are usually stronger for the right than the left hand. Most studies have shown that the 2D:4D ratio does not vary with age or postnatal concentration of sex steroid hormones. Recently, a strong association between left hand 2D:4D ratio and infection with a common human parasite Toxoplasma has been reported. We hypothesized that the confounding effect of Toxoplasma infection on left hand 2D:4D ratio could be responsible for the stronger association between different traits and right hand rather than left hand 2D:4D ratio. This confounding effect of toxoplasmosis could also be responsible for the difficulty in finding an association between 2D:4D ratio and age or postnatal steroid hormone concentration. To test this hypothesis, we analyzed the association between sex and age and 2D:4D ratio in a population of 194 female and 106 male students with and without controlling for the confounding variables of Toxoplasma infection and testosterone concentration. Our results showed that the relationship between age and sex and 2D:4D ratio increased sharply when Toxoplasma infection and testosterone concentration were controlled. These results suggest that left hand 2D:4D ratio is more susceptible to postnatal influences and that the confounding factors of Toxoplasma infection, testosterone concentration and possibly also age, should be controlled in future 2D:4D ratio studies. Because of a stronger 2D:4D dimorphism in Toxoplasma-infected than Toxoplasma-free subjects, we predict that 2D:4D ratio dimorphism as well as right hand/left hand 2D:4D ratio dimorphism will be higher in countries with a high prevalence of Toxoplasma infection than in those with a low prevalence. Am J Phys Anthropol 137:479-484, 2008. (C) 2008 Wiley-Liss, Inc.

Tagged: 2D:4D, 2nd-digit, 4th digit ratio, androgens, asymmetry, finger-length ratios, gender differences, infection, jamaican children, men, orientation, postnatal changes, sexual-dimorphism, Toxoplasma, women

BehaviorMorphology

Topics

  • Behavior 105
  • Cognitive functions 64
  • Mental health 439
  • Morphology 6
  • Motor functions 10
  • Personality 36
  • Physical health 134
  • Reproduction 36
  • Reviews 40
  • Sensory functions 3
  • Uncategorized 2

Archives

Recent articles

  • Mortality Patterns of Toxoplasmosis and Its Comorbidities in Tanzania: A 10-Year Retrospective Hospital-Based Survey February 6, 2020
  • The role of latent toxoplasmosis in the aetiopathogenesis of schizophrenia–the risk factor or an indication of a contact with cat? February 6, 2020
  • The Association between Toxoplasma gondii Infection and Risk of Parkinson’s Disease: A Systematic Review and Meta-Analysis February 6, 2020

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