Increased incidence of traffic accidents in Toxoplasma-infected military drivers and protective effect RhD molecule revealed by a large-scale prospective cohort study

Department of philosophy, Faculty of Science, Charles University, Prague, Czech Republic.
BMC Infectious Diseases (Impact Factor: 2.61). 02/2009; 9(1):72. DOI: 10.1186/1471-2334-9-72
Source: PubMed


Latent toxoplasmosis, protozoan parasitosis with prevalence rates from 20 to 60% in most populations, is known to impair reaction times in infected subjects, which results, for example, in a higher risk of traffic accidents in subjects with this life-long infection. Two recent studies have reported that RhD-positive subjects, especially RhD heterozygotes, are protected against latent toxoplasmosis-induced impairment of reaction times. In the present study we searched for increased incidence of traffic accidents and for protective effect of RhD positivity in 3890 military drivers.
Male draftees who attended the Central Military Hospital in Prague for regular entrance psychological examinations between 2000 and 2003 were tested for Toxoplasma infection and RhD phenotype at the beginning of their 1 to 1.5-year compulsory military service. Subsequently, the data on Toxoplasma infection and RhD phenotype were matched with those on traffic accidents from military police records and the effects of RhD phenotype and Toxoplasma infection on probability of traffic accident was estimated with logistic regression.
We confirmed, using for the first time a prospective cohort study design, increased risk of traffic accidents in Toxoplasma-infected subjects and demonstrated a strong protective effect of RhD positivity against the risk of traffic accidents posed by latent toxoplasmosis. Our results show that RhD-negative subjects with high titers of anti-Toxoplasma antibodies had a probability of a traffic accident of about 16.7%, i.e. a more than six times higher rate than Toxoplasma-free or RhD-positive subjects.
Our results showed that a common infection by Toxoplasma gondii could have strong impact on the probability of traffic accident in RhD negative subjects. The observed effects could provide not only a clue to the long-standing evolutionary enigma of the origin of RhD polymorphism in humans (the effect of balancing selection), but might also be the missing piece in the puzzle of the physiological function of the RhD molecule.


Available from: Jaroslav Flegr
  • Source
    • "Parasitism is one of the most important driving forces in ecology because it affects the distribution and abundance of organisms on local and global scales (Piersma, 1997; Tompkins & Begon, 1999) and many ecosystem processes (Marcogliese, 2004). Parasites potentially affect the life and death of essentially every organism (Price, 1980), from insects (Worden, Parker & Pappas, 2000) to humans (Fl egr et al., 2009). Accordingly, parasite–host systems are a subject of coevolution, with many particular adaptations for successful parasitism or, conversely, for the avoidance of parasitism (Combes, 2001). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Parasitic species can affect host behaviour in various ways. Freshwater mussels of the superfamily Unionoidea have a glochidia larva that is parasitic on fish. Our aim was to evaluate whether fish exposed to glochidia have distinct behaviour that could affect the upstream dispersal of the parasite.Many freshwater mussels are highly endangered, and understanding the relationships with their hosts is important for their conservation. However, research on the behavioural effects of parasitism on fish host activity and/or the upstream dispersal of mussel larvae in nature has received little attention.Specifically, we examined a fish (the chub, Squalius cephalus) that hosts the larval stage of a freshwater bivalve (Anodonta anatina) and investigated alterations in host behaviour induced by the parasite. One laboratory and two field experiments were conducted using passive integrated transponder systems and radio-telemetry.Infected fish were generally less active in the laboratory and, in the field, dispersed less far upstream. Moreover, radio-telemetry revealed a habitat shift by the infected fish, which were found further from the riverbank.We suggest that behavioural changes in the fish that are induced by glochidia do not facilitate the long-distance dispersal of the mussel but rather cause reductions in fish activity and slight habitat shifts. Possible consequences of such behavioural alterations are discussed.
    Freshwater Biology 03/2014; 59(7). DOI:10.1111/fwb.12357 · 2.74 Impact Factor
  • Source
    • "Our findings support previous observations in this new but growing research area [14-16]. Taken together, this study and previous findings suggests that the increased risk of traffic accidents could possibly be the consequence of acute toxoplasmosis, rather than the increasing effect of latent toxoplasmosis, a hypothesis previously proposed by studies conducted in the Czech Republic and Turkey [14-16]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background The prevalence of toxoplasmosis in the general population of Guadalajara, Mexico, is around 32%. Toxoplasmosis can cause ocular lesions and slowing of reaction reflexes. Latent toxoplasmosis has been related with traffic accidents. We aimed to assess the prevalence of anti-Toxoplasma gondii antibodies and visual impairments related with traffic accidents in drivers from the metropolitan Guadalajara. Methods We prospectively evaluated the prevalence of IgG and IgM anti-T. gondii antibodies in 159 individuals involved in traffic accidents, and in 164 control drivers never involved in accidents. Cases of toxoplasmosis reactivation or acute infection were detected by PCR in a subset of 71 drivers studied for the presence of T. gondii DNA in blood samples. Ophthalmologic examinations were performed in drivers with IgG anti-T. gondii antibodies in search of ocular toxoplasmosis. Results Fifty-four (34%) traffic accident drivers and 59 (36%) controls were positive to IgG anti-T. gondii antibodies (p = 0.70). Among the 113 seropositive participants, mean anti-T. gondii IgG antibodies titers were higher in traffic accident drivers than in controls (237.9 ± 308.5 IU/ml vs. 122.9 ± 112.7 IU/ml, respectively; p = 0.01 by Student’s t test, p = 0.037 by Mann–Whitney U test). In multivariate analyses, anti-T. gondii IgG antibody titers were consistently associated with an increased risk of traffic accidents, whereas age showed an inverse association. The presence of IgM-anti-T. gondii antibodies was found in three (1.9%) subjects among traffic accident drives, and in two (1.2%) controls. Three (4.2%) samples were positive for the presence of T. gondii DNA, all among seropositive individuals. No signs of ocular toxoplasmosis were found in the entire cohort. Moreover, no other ocular conditions were found to be associated with the risk of traffic accidents in a multivariate analysis. Conclusions Anti-T. gondii antibody titers are associated with the risk of traffic accidents. We could not determine any association of ocular toxoplasmosis with traffic accidents. Our results warrant further analyses in order to clarify the link between toxoplasmosis and traffic accidents.
    Parasites & Vectors 10/2013; 6(1). DOI:10.1186/1756-3305-6-294 · 3.43 Impact Factor
  • Source
    • "Existence of the interaction between toxoplasmosis, RhD phenotype and human behaviour has been confirmed in four studies. Two of them have shown resistance of RhD-positive subjects, especially the RhD-positive heterozygotes, to impairment of reaction times after Toxoplasma infection [27], [28] and one prospective study performed on 3900 military drivers has found an increased risk of traffic accidents in Toxoplasma-infected, RhD-negative subjects [30]. The fourth study has reported opposite relation of toxoplasmosis with Cattell's ego strength, praxernia, and ergic tension and Cloninger's cooperativeness in RhD-positive and RhD-negative blood donors [29]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The parasite Toxoplasma gondii influences the behaviour of infected animals and probably also personality of infected humans. Subjects with a Rhesus-positive blood group are protected against certain behavioural effects associated with Toxoplasma infection, including the deterioration of reaction times and personality factor shift. Here, we searched for differences in the toxoplasmosis-associated effects between RhD-positive and RhD-negative subjects by testing 502 soldiers with two personality tests and two intelligence tests. The infected subjects expressed lower levels of all potentially pathognomic factors measured with the N-70 questionnaire and in neurasthenia measured with NEO-PI-R. The RhD-positive, Toxoplasma-infected subjects expressed lower while RhD-negative, Toxoplasma-infected subjects expressed higher intelligence than their Toxoplasma-free peers. The observed Toxoplasma-associated differences were always larger in RhD-negative than in RhD-positive subjects. RhD phenotype plays an important role in the strength and direction of association between latent toxoplasmosis and not only psychomotor performance, but also personality and intelligence.
    PLoS ONE 04/2013; 8(4):e61272. DOI:10.1371/journal.pone.0061272 · 3.23 Impact Factor
Show more