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Toxoplasma gondii & Human Phenotype

Compendium of Known Effects and Ongoing Research

Morphology

No association between latent toxoplasmosis and multiple body measures in US adults

October 6, 2016
Berrett, A. N., Gale, S. D., Erickson, L. D., Brown, B. L., Hedges, D. W.
Folia Parasitologica 2016; 63: 034, 10.14411/Fp.2016.034
Click for abstract
Toxoplasma gondii (Nicolle et Manceaux, 1908) is an intracellular parasite that can cause ongoing latent infection persisting for the duration of a non-definitive host's life. Affecting approximately one-third of the world's population, latent toxoplasmosis has been associated with neuropsychological outcomes and a previous report suggested an association between latent toxoplasmosis and adult height. Given the large number of people with latent toxoplasmosis and its potential associations with human height, we sought to better understand the association between latent toxoplasmosis and human morphology by evaluating seropositivity for T. gondii and multiple body measures reported in the National Health and Nutrition Examination Survey III (NHANES III) and in the more recent continuous NHANES data sets from the United States Centers for Disease Control and Prevention for which data on T. gondii are available. In these analyses, latent toxoplasmosis was not associated with any of the body measures assessed in the NHANES datasets even after taking into account interactions between latent toxoplasmosis and testosterone suggesting that in these samples, latent toxoplasmosis is not associated with adult morphology including height.

Tagged: bmi, gondii, height, seroprevalence, testosterone, Toxoplasma gondii, united-states

Morphology

Increased body mass index in Toxoplasma gondii positive patients with schizophrenia

October 12, 2012
Mazaheri, S., Okusaga, O., Reeves, G., Giegling, I., Hartmann, A. M., Konte, B., Friedl, M., Rujescu, D., Postolache, T. T.
Biological Psychiatry 2012; 71: 280S-280S
Tagged: bmi, immune activation, Schizophrenia, Toxoplasma gondii

Mental healthMorphology

Latent toxoplasmosis and salivary testosterone concentration – important confounding factors in second to fourth digit ratio studies

September 26, 2008
Flegr, J., Lindová, J., Pivonkova, V. , Havlicek, J.
American Journal of Physical Anthropology 2008; 20: 487-489
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 ste- roid 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 hypothe- sized 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 confound- ing effect of toxoplasmosis could also be responsible for the difficulty in finding an association between 2D:4D ratio and age or postnatal steroid hormone concentra- tion. 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 infec- tion and testosterone concentration were controlled. These results suggest that left hand 2D:4D ratio is more susceptible to postnatal influences and that the con- founding 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 Toxo- plasma -free subjects, we predict that 2D:4D ratio dimor- phism 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

Tagged: 2D:4D, androgens, infection, postnatal changes, Toxoplasma

MorphologyPhysical health

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

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
Click for abstract
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

BehaviorMorphologyPersonality

Body height, body mass index, waist-hip ratio, fluctuating asymmetry and second to fourth digit ratio in subjects with latent toxoplasmosis

September 26, 2005
Flegr, J. Hrusková, M., Hodný, Z., Hanusová, J.
Parasitology 2005; 130: 621-628
Click for abstract
Between 20% and 60% of the population of most countries are infected with the protozoan Toxoplasma gondii . Subjects with clinically asymptomatic life-long latent toxoplasmosis differ from those who are Toxoplasma free in several behavioural parameters. Case-control studies cannot decide whether these differences already existed before infection or whether they were induced by the presence of Toxoplasma in the brain of infected hosts. Here we searched for such morphological differences between Toxoplasma -infected and Toxoplasma -free subjects that could be induced by the parasite (body weight, body height, body mass index, waist-hip ratio), or could rather correlate with their natural resistance to parasitic infection (fluctuating asymmetry, 2D : 4D ratio). We found Toxoplasma -infected men to be taller and Toxoplasma -infected men and women to have lower 2D : 4D ratios previously reported to be associated with higher pre-natal testosterone levels. The 2D : 4D ratio negatively correlated with the level of specific anti- Toxoplasma antibodies in Toxoplasma -free subjects. These results suggest that some of the observed differences between infected and non-infected subjects may have existed before infection and could be caused by the lower natural resistance to Toxoplasma infection in subjects with higher pre-natal testosterone levels.

Tagged: (2D : 4D), ds: human, immunity, immunocompetence handicap hypothesis, resistance, testosterone, Toxoplasma

Morphology

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

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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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