Human

Latent Toxoplasma gondii infection leads to deficits in goal-directed behavior in healthy elderly

October 10, 2014
Beste, C., Getzmann, S., Gajewski, P. D., Golka, K., Falkenstein, M
Neurobiology of Aging 2014; 35: 1037-1044.

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The parasite Toxoplasma gondii has been found to manipulate the behavior of its secondary hosts to increase its own dissemination which is commonly believed to be to the detriment of the host (manipulation hypothesis). The manipulation correlates with an up-regulation of dopaminergic neurotransmission. In humans, different pathologies have been associated with T. gondii infections but most latently infected humans do not seem to display overt impairments. Since a dopamine plus does not necessarily bear exclusively negative consequences in humans, we investigated potential positive consequences of latent toxoplasmosis (and the presumed boosting of dopaminergic neurotransmission) on human cognition and behavior. For this purpose, we focused on action cascading which has been shown to be modulated by dopamine. Based on behavioral and neurophysiological (EEG) data obtained by means of a stop-change paradigm, we were able to demonstrate that healthy young humans can actually benefit from latent T. gondii infection as regards their performance in this task (as indicated by faster response times and a smaller P3 component). The data shows that a latent infection which is assumed to affect the dopaminergic system can lead to paradoxical improvements of cognitive control processes in humans.

Tagged: action cascading, animal behavior, attention, basal ganglia, cognitive flexibility, Dopamine, eeg, error, event-related potentials, executive function, executive functions, Human, latent toxoplasmosis, manipulation hypothesis, modulation, Parasite, parkinson's disease, stop-change paradigm, toxoplama gondii

Mental health

Latent Toxoplasma gondii infection leads to improved action control

October 10, 2014
Stock, A. K., von Heinegg, E. H., Kohling, H. L., Beste, C.
Brain Behavior and Immunity 2014; 37: 103-108

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Cognitive functions Mental health Motor functions

Parasitic infections and pregnancy complications

October 29, 2011
Pavlinova, J., Kincekova, J., Ostro, A., Saksun, L., Vasilkova, Z., Konigova, A.
Helminthologia 2011; 48: 8-12

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Infections of various aetiology during pregnancy present a serious risk factor that can lead to abortion, premature birth, stillbirth, birth of newborn with genetic developmental defects, or seemingly healthy infant that may develop symptoms later in life. A total of 530 sera of patients from gynaecology departments were examined for antibodies against Toxoplasma gondii, Toxocara spp. and Listeria monocytogenes using ELISA (IgG, IgM). In women with habitual abortions we determined up to 42.1 % seroprevalence of IgG antibodies against T. gondii. The prevalence of antibodies was statistically significant (p < 0.0004) when compared to control group (25.1 %). In the patients diagnosed with sterility the prevalence of antibodies (26.3 %) was similar to that of control group. The prevalence of antibodies against Toxocara spp. (5.5 %) and Listeria monocytogenes (2.3 %) in patients with habitual abortions were similar to those of women in the general population.

Tagged: abortion, elisa, Human, listeria monocytogenes, listeriosis, population, pregnancy, prevalence, risk factors, seroprevalence, toxocara spp., Toxoplasma gondii, toxoplasma-gondii antibodies, women

Physical health Reproduction

Higher perceived dominance in Toxoplasma infected men – a new evidence for role of increased level of testosterone in toxoplasmosis-associated changes in human behavior

September 26, 2007
Hodková, H., Kolbeková, P., Skallová, A., Lindová, J. , Flegr, J.
Neuroendocrinology Letters 2007; 28: 110-114

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Toxoplasma is parasite of cats that uses any warm-blooded animals as intermediate hosts. It is known to induce shifts in behavior, physiology and even morphology of its intermediate hosts, including humans. The lower second to fourth digit ratio (2D:4D ratio) in infected man and women, and higher height in infected man sug - gest that sex steroid hormones like testosterone could play a role in these shifts. Here, we searched for another indirect indication for a higher postnatal testosterone level, i.e. increased perceived dominance and masculinity in infected men. We showed portrait pictures of 89 male students of which 18 were Toxoplasma - infected to 109 female students. When we statistically corrected for age, men with latent toxoplasmosis were perceived as more dominant (p=0.009) and masculine (p=0.052). These results support the idea that the higher level of testosterone could be responsible for at least some of the toxoplasmosis-associated shifts in human and animal behavior.

Tagged: Human, masculinity, Parasite

Behavior Morphology Personality

Gender differences in behavioural changes induced by latent toxoplasmosis

September 26, 2006
Lindová, J., Novotná, M., Havlícek, J., Smídová, E., Skallová, A., Kolbeková, P., Hodný, Z., Kodym, P. , Flegr, J.
International Journal for Parasitology 2006; 36: 1485-1492

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There is growing evidence that the protozoan Toxoplasma gondii modifies behaviour of its intermediate hosts, including humans, where it globally infects about 20–60% of the population. Although it is considered asymptomatic in its latent stage, it was previously found to have remarkable and gender different effects on the personality factors A (warmth), G (rule consciousness), L (vigilance, mis- trust) and Q3 (self-control, self-image) from Cattell’s 16PF Questionnaire. We performed a double blind experiment testing 72 and 142 uninfected men and women, respectively, and 20 and 29 infected men and women, respectively, in order to verify these gender differences using behavioural experiments. Our composite behavioural variables Self-Control and Clothes Tidiness (analogue to the 16PF factors G – conscientiousness and Q3 – self-control) showed a significant effect of the toxoplasmosis–gender interaction with infected men scoring significantly lower than uninfected men and a trend in the opposite direction in women. The effect of the toxoplasmosis–gender inter- action on our composite behavioural variable Relationships (analogue to factor A – warmth) approached significance; infected men scored significantly lower than uninfected men whereas there was no difference in women. In the composite behavioural variable Mistrust (analogue to factor L), the pattern was affected by environment (rural versus urban). Possible interpretations of the gender differences are discussed.

Tagged: 16PF, Human, manipulation hypothesis, Toxoplasma

Behavior Personality

Decrease of psychomotor performance in subjects with latent “asymptomatic” toxoplasmosis

September 26, 2001
Havlícek, J., Gasová, Z., Smith, A. P. , Zvára, K, J. Flegr, J.
Parasitology 2001; 122: 515-520

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Toxoplasma gondii is known to induce speciÆc behavioural changes in its intermediate hosts. This is usually considered to be an evolutionary adaptation aimed to increase the probability of transmission of the parasite into its deÆnitive host, the cat, by predation. In rodents an increase of reaction time as well as many other speciÆc behavioural patterns have been observed. Here we report the results of our double blind study showing the signiÆcantly longer reaction times of 60 subjects with latent toxoplasmosis in comparison with those of 56 controls. Moreover, the existence of a positive correlation between length of infection and mean reaction time suggested that slow and cumulative effects of latent toxoplasmosis rather than a one-step (and possibly transient) effect of acute toxoplasmosis disease are responsible for the decrease of psychomotor performance of infected subjects. To our knowledge, this is the Ærst study conÆrming the existence of such parasite-induced changes in human behaviour that could be considered in evolutionary history of the human species as adaptive from the point of view of parasite transmission.

Tagged: behaviour, evolution, Human, manipulation hypothesis, Parasite, reaction times, Toxoplasma gondii

Cognitive functions Motor functions

Correlation of duration of latent Toxoplasma gondii infection with personality changes in women

September 26, 2000
Flegr, J., Kodym, P.,Tolarová, V.
Biological Psychology 2000; 53: 57-68

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Many parasites induce characteristic changes in behavior of their hosts. In humans latent toxoplasmosis is associated with changes in personality profiles. It has been already shown that a decrease in superego strength is correlated with duration of toxoplasmosis in men. Here we studied changes in personality profiles with Cattell’s 16 PF questionnaire in Toxoplasma -infected women. The changes were measured as differences in personality factors between Toxoplasma -infected subjects and uninfected controls of the same age. The low-rate changes were studied in 230 women diagnosed with acute toxoplasmosis during past 14 years. The results showed the correlation between duration of toxoplasmosis and level of factors G (high superego strength) and Q3 (high strength of self sentiment). The high-rate changes were estimated by measuring the correlation between level of Toxoplasma -antibody titers (which rapidly decline after the end of acute phase of toxoplasmosis) and personality factors in an experimental set of 55 young mothers with latent toxoplasmosis. Again, certain factors, namely A (affectothymia), F (surgence), G (high superego strength), H (parmia), and L (protension), correlated with the length of the infection. We suggest that the parasite induced the changes in the personality profiles of the women because of our observation of an increasingly different personality profile over time between women with latent infection and controls. The same evidence questions the view that women with a particular personality profile are more prone to acquisition

Tagged: 16PF, behavior, Cattell's questionnaire, Human, manipulation hypothesis, Parasite, Toxoplasma gondii

Personality

Toxoplasma gondii & Human Phenotype

Compendium of Known Effects and Ongoing Research

Human

Parasitic infections and pregnancy complications

Higher perceived dominance in Toxoplasma infected men – a new evidence for role of increased level of testosterone in toxoplasmosis-associated changes in human behavior

Gender differences in behavioural changes induced by latent toxoplasmosis

Decrease of psychomotor performance in subjects with latent “asymptomatic” toxoplasmosis

Correlation of duration of latent Toxoplasma gondii infection with personality changes in women