Lower performance of Toxoplasma-infected, Rh-negative subjects in the weight holding and hand-grip tests

Abstract

Toxoplasma, a protozoan parasite of cats, infects many species of intermediate and paratenic hosts, including about one-third of humans worldwide. After a short phase of acute infection, the tissue cysts containing slowly dividing bradyzoites are formed in various organs and toxoplasmosis proceeds spontaneously in its latent form. In immunocompetent subjects, latent toxoplasmosis was considered asymptomatic. However, dozens of studies performed on animals and humans in the past twenty years have shown that it is accompanied by a broad spectrum of specific behavioural, physiological and even morphological changes. In human hosts, the changes often go in the opposite direction in men and women, and are mostly weaker or non-existent in Rh-positive subjects. Here, we searched for the indices of lower endurance of the infected subjects by examining the performance of nearly five hundred university students tested for toxoplasmosis and Rh phenotype in two tests, a weight holding test and a grip test. The results confirmed the existence of a negative association of latent toxoplasmosis with the performance of students, especially Rh-negative men, in these tests. Surprisingly, but in an accordance with some already published data, Toxoplasma-infected, Rhpositive subjects expressed a higher, rather than lower, performance in our endurance tests. Therefore, the results only partly support the hypothesis for the lower endurance of Toxoplasma infected subjects as the performance of Rh-positive subjects (representing majority of population) correlated positively with the Toxoplasma infection.Keywords: Toxoplasmosis; behaviour; endurance; performance; psychology; grip holding test.. CC-BY-NC-ND 4.0 International license not peer-reviewed) is the author/funder. It is made available under aThe copyright holder for this preprint (which was . http://dx.doi.org/10.1101/264093 doi: bioRxiv preprint first posted online Feb. 13, 2018; 3 Introduction About one third of the world population are infected with the protozoan parasite Toxoplasma gondii (Tenter et al., 2000). In immunocompetent subjects, after a short phase of acute toxoplasmosis promoted by tachyzoites, the disease spontaneously proceeds into its latent phase, which is characterized by the presence of tissue cysts with a slowly dividing form of the parasite, bradyzoites, in various organs and anamnestic IgG antibodies in blood (Pappas et al., 2009). Latent toxoplasmosis has been considered asymptomatic for a long time, however, during the past 20 years, about one hundred papers have been published showing that Toxoplasma seropositive and seronegative subjects differ in many personality traits (Flegr & Hrdý, 1994;Flegr et al., 2003), performance in certain psychomotor tests (Havlíček et al., 2001;Pearce et al., 2013), cognitive tests (Dickerson et al., 2014;Ferreira et al., 2013;Flegr et al., 2012;Pearce et al., 2014) and also in the incidence and form of many diseases and disorders (Flegr & Escudero, 2016;Flegr et al., 2014). In some tests, however, Toxoplasma-i...

The role of balancing selection in maintaining human RhD blood group polymorphism: A preregistered cross‐sectional study

“…(2008) showed that in a Toxoplasma ‐free people, RhD‐positive homozygotes performed slightly worse on psychomotor tasks than RhD‐positive heterozygotes but much worse than RhD‐negative homozygotes. In Toxoplasma ‐infected subjects, on the other hand, RhD‐positive homozygotes performed equally poorly as RhD‐negative homozygotes, and much worse than RhD‐positive heterozygotes (see also Flegr et al., 2018, for a confirmatory study).…”

“…Several papers showed that subjects with the RhD‐positive phenotype—and especially heterozygotes with one D and one d allele—are protected against certain adverse factors. Most prominent is protection against the health impact of toxoplasmosis, a common chronic infection by a protist parasite, but various studies also found indications of protection against the effects of fatigue, smoking and ageing (Flegr et al., 2010, 2012, 2018; Holub et al., 2011; Kaňková et al., 2010; Novotná et al., 2008). More recently, an ecological correlative study performed in 66 countries for which allele frequencies and WHO data on the incidence of 125 disorders were available (WHO, 2008) showed that the incidence of many disorders correlates positively with the frequency of RhD‐negative subjects and negatively with the frequency of RhD‐positive heterozygotes in the population (Flegr, 2016).…”

Rhesus-minus phenotype as a predictor of sexual desire and behavior, wellbeing, mental health, and fecundity

“…It will be therefore necessary to repeat the study on the population of people with empirically examined Rh phenotype, or preferably genotype. Such studies have been already done for other traits demonstrating, for example, the association between Rh phenotype and performance in weight-holding and handgrip tests [ 14 ], intelligence [ 13 ], psychomotor performance [ 10 – 12 ], and several personality traits [ 32 ]. It must be mentioned, however, that a large binational cohort study found no difference in mortality of Rh-positive and Rh-negative subjects [ 33 ].…”

“…With the exception of this immunological effect and sporadic reports about the possible association of Rh negativity with certain personality traits [ 9 ], no effects of the Rh genotype on human phenotype have been described. Recently, however, several studies suggested the existence of specific effects of Rh phenotype and genotype on human psychomotor performance [ 10 – 14 ] and health [ 15 – 17 ]. Generally, Rh-negative subjects have worse health, score worse in some performance tests, and express higher sensitivity to various negative environmental factors, such as Toxoplasma infection and smoking.…”

ABO blood type analysis in patients with chronic obstructive pulmonary disease

“…The results of this study might also point to such conclusions (Rh negative A blood type is most prevalent in subjects in a very severe stage of COPD), but this should be investigated in more detail. The Rhnegative phenotype was associated with a slower response to Toxoplasma gondii infection in the study of soldiers in the Czech Republic (FLEGR et al, 2009;FLEGR et al, 2018). A study conducted in Spain (Basque Country) highlighted the negative correlation between Rh-negative factor and liver transplantation (HANVESAKUL et al, 2008).…”