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

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>Male draftees who attended the Central Military Hospital in Prague for regular entrance psychological examinations between 2000 and 2003 were tested for <it>Toxoplasma </it>infection and RhD phenotype at the beginning of their 1 to1.5-year compulsory military service. Subsequently, the data on <it>Toxoplasma </it>infection and RhD phenotype were matched with those on traffic accidents from military police records and the effects of RhD phenotype and <it>Toxoplasma </it>infection on probability of traffic accident was estimated with logistic regression.</p> <p>Results</p> <p>We confirmed, using for the first time a prospective cohort study design, increased risk of traffic accidents in <it>Toxoplasma</it>-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-<it>Toxoplasma </it>antibodies had a probability of a traffic accident of about 16.7%, i.e. a more than six times higher rate than <it>Toxoplasma</it>-free or RhD-positive subjects.</p> <p>Conclusion</p> <p>Our results showed that a common infection by <it>Toxoplasma gondii </it>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.</p

Longer pregnancy and slower fetal development in women with latent "asymptomatic" toxoplasmosis

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to confirm that women with latent toxoplasmosis have developmentally younger fetuses at estimated pregnancy week 16 and to test four exclusive hypotheses that could explain the observed data.</p> <p>Methods</p> <p>In the present retrospective cohort study we analysed by the GLM (general linear model) method data from 730 <it>Toxoplasma</it>-free and 185 <it>Toxoplasma</it>-infected pregnant women.</p> <p>Results</p> <p>At pregnancy week 16 estimated from the date of the last menstruation, the mothers with latent toxoplasmosis had developmentally younger fetuses based on ultrasound scan (<it>P </it>= 0.014). Pregnancy of <it>Toxoplasma</it>-positive compared to <it>Toxoplasma</it>-negative women was by about 1.3 days longer, as estimated both from the date of the last menstruation (<it>P </it>= 0.015) and by ultrasonography (<it>P </it>= 0.025).</p> <p>Conclusion</p> <p>The most parsimonious explanation for the observed data is retarded fetal growth during the first weeks of pregnancy in <it>Toxoplasma</it>-positive women. The phenomenon was only detectable in multiparous women, suggesting that the immune system may play some role in it.</p

Probable neuroimmunological link between Toxoplasma and cytomegalovirus infections and personality changes in the human host

BACKGROUND: Recently, a negative association between Toxoplasma-infection and novelty seeking was reported. The authors suggested that changes of personality trait were caused by manipulation activity of the parasite, aimed at increasing the probability of transmission of the parasite from an intermediate to a definitive host. They also suggested that low novelty seeking indicated an increased level of the neurotransmitter dopamine in the brain of infected subjects, a phenomenon already observed in experimentally infected rodents. However, the changes in personality can also be just a byproduct of any neurotropic infection. Moreover, the association between a personality trait and the toxoplasmosis can even be caused by an independent correlation of both the probability of Toxoplasma-infection and the personality trait with the third factor, namely with the size of living place of a subject. To test these two alternative hypotheses, we studied the influence of another neurotropic pathogen, the cytomegalovirus, on the personality of infected subjects, and reanalyzed the original data after the effect of the potential confounder, the size of living place, was controlled. METHODS: In the case-control study, 533 conscripts were tested for toxoplasmosis and presence of anti-cytomegalovirus antibodies and their novelty seeking was examined with Cloninger's TCI questionnaire. Possible association between the two infections and TCI dimensions was analyzed. RESULTS: The decrease of novelty seeking is associated also with cytomegalovirus infection. After the size of living place was controlled, the effect of toxoplasmosis on novelty seeking increased. Significant difference in novelty seeking was observed only in the largest city, Prague. CONCLUSION: Toxoplasma and cytomegalovirus probably induce a decrease of novelty seeking. As the cytomegalovirus spreads in population by direct contact (not by predation as with Toxoplasma), the observed changes are the byproduct of brain infections rather than the result of manipulation activity of a parasite. Four independent lines of indirect evidence, namely direct measurement of neurotransmitter concentration in mice, the nature of behavioral changes in rodents, the nature of personality changes in humans, and the observed association between schizophrenia and toxoplasmosis, suggest that the changes of dopamine concentration in brain could play a role in behavioral changes of infected hosts

Chronic Toxoplasma Infection Modifies the Structure and the Risk of Host Behavior

The intracellular parasite Toxoplasma has an indirect life cycle, in which felids are the definitive host. It has been suggested that this parasite developed mechanisms for enhancing its transmission rate to felids by inducing behavioral modifications in the intermediate rodent host. For example, Toxoplasma-infected rodents display a reduction in the innate fear of predator odor. However, animals with Toxoplasma infection acquired in the wild are more often caught in traps, suggesting that there are manipulations of intermediate host behavior beyond those that increase predation by felids. We investigated the behavioral modifications of Toxoplasma-infected mice in environments with exposed versus non-exposed areas, and found that chronically infected mice with brain cysts display a plethora of behavioral alterations. Using principal component analysis, we discovered that most of the behavioral differences observed in cyst-containing animals reflected changes in the microstructure of exploratory behavior and risk/unconditioned fear. We next examined whether these behavioral changes were related to the presence and distribution of parasitic cysts in the brain of chronically infected mice. We found no strong cyst tropism for any particular brain area but found that the distribution of Toxoplasma cysts in the brain of infected animals was not random, and that particular combinations of cyst localizations changed risk/unconditioned fear in the host. These results suggest that brain cysts in animals chronically infected with Toxoplasma alter the fine structure of exploratory behavior and risk/unconditioned fear, which may result in greater capture probability of infected rodents. These data also raise the possibility that selective pressures acted on Toxoplasma to broaden its transmission between intermediate predator hosts, in addition to felid definitive hosts

Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads

<p>Abstract</p> <p>Background</p> <p>Fornicata is a relatively recently established group of protists that includes the diplokaryotic diplomonads (which have two similar nuclei per cell), and the monokaryotic enteromonads, retortamonads and <it>Carpediemonas</it>, with the more typical one nucleus per cell. The monophyly of the group was confirmed by molecular phylogenetic studies, but neither the internal phylogeny nor its position on the eukaryotic tree has been clearly resolved.</p> <p>Results</p> <p>Here we have introduced data for three genes (SSU rRNA, α-tubulin and HSP90) with a wide taxonomic sampling of Fornicata, including ten isolates of enteromonads, representing the genera <it>Trimitus </it>and <it>Enteromonas</it>, and a new undescribed enteromonad genus. The diplomonad sequences formed two main clades in individual gene and combined gene analyses, with <it>Giardia </it>(and <it>Octomitus</it>) on one side of the basal divergence and <it>Spironucleus</it>, <it>Hexamita </it>and <it>Trepomonas </it>on the other. Contrary to earlier evolutionary scenarios, none of the studied enteromonads appeared basal to diplokaryotic diplomonads. Instead, the enteromonad isolates were all robustly situated within the second of the two diplomonad clades. Furthermore, our analyses suggested that enteromonads do not constitute a monophyletic group, and enteromonad monophyly was statistically rejected in 'approximately unbiased' tests of the combined gene data.</p> <p>Conclusion</p> <p>We suggest that all higher taxa intended to unite multiple enteromonad genera be abandoned, that <it>Trimitus </it>and <it>Enteromonas </it>be considered as part of Hexamitinae, and that the term 'enteromonads' be used in a strictly utilitarian sense. Our result suggests either that the diplokaryotic condition characteristic of diplomonads arose several times independently, or that the monokaryotic cell of enteromonads originated several times independently by secondary reduction from the diplokaryotic state. Both scenarios are evolutionarily complex. More comparative data on the similarity of the genomes of the two nuclei of diplomonads will be necessary to resolve which evolutionary scenario is more probable.</p

Decrease of psychomotor performance in subjects with latent 'asymptomatic' toxoplasmosis

Toxoplasma gondii is known to induce specific 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 definitive host, the cat, by predation. In rodents an increase of reaction time as well as many other specific behavioural patterns have been observed. Here we report the results of our double blind study showing the significantly 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 first study confirming 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

High seroprevalence of Toxoplasma gondii infection in a subset of Mexican patients with work accidents and low socioeconomic status

<p>Abstract</p> <p>Background</p> <p><it>Toxoplasma gondii </it>has been associated with reflex impairment and traffic accidents. It is unknown whether <it>Toxoplasma </it>infection might be associated with work accidents. Therefore, using a case-control seroprevalence study design, 133 patients with a recent work accident and 266 control subjects of the general population from the same region were examined with enzyme-linked immunoassays for the presence and levels of anti-<it>Toxoplasma </it>IgG antibodies and anti-<it>Toxoplasma </it>IgM antibodies. Socio-demographic, work, clinical and behavioral characteristics from each worker were obtained.</p> <p>Results</p> <p>Eleven (8.3%) of 133 patients, and 14 (5.3%) of 266 controls had anti-<it>T. gondii </it>IgG antibodies. Anti-<it>T. gondii </it>IgG levels were higher than 150 IU/ml in 8 (6%) patients and 10 (3.8%) controls. Anti-<it>T. gondii </it>IgM antibodies were found in one (0.8%) of the workers, and in 6 (2.3%) of the controls. No statistically significant differences in the IgG seroprevalences, frequencies of high IgG levels, and IgM seroprevalences among patients and controls were found. In contrast, a low socio-economic level in patients with work accidents was associated with <it>Toxoplasma </it>seropositivity (<it>P </it>= 0.01). Patients with work accidents and low socioeconomic status showed a significantly (OR = 3.38; 95% CI: 0.84-16.06; <it>P </it>= 0.04) higher seroprevalence of <it>T. gondii </it>infection than controls of the same socioeconomic status (15.1% vs. 5%, respectively). Multivariate analysis showed a positive association of <it>T. gondii </it>infection with boar meat consumption (OR = 3.04; 95% CI: 1.03-8.94; <it>P </it>= 0.04). In contrast, a negative association between <it>T. gondii </it>infection and national trips (OR = 0.40; 95% CI: 0.17-0.96; <it>P </it>= 0.04), sausage consumption (OR = 0.20; 95% CI: 0.05-0.68; <it>P </it>= 0.01), and ham consumption (OR = 0.16; 95% CI: 0.05-0.51; <it>P </it>= 0.002) was found.</p> <p>Conclusions</p> <p>In the study described here seropositivity to <it>T. gondii </it>was associated to work accidents in a subset of patients with low socioeconomic status. This is the first report of an association of <it>T. gondii </it>infection and work accidents. Further studies to confirm our results are needed. Results may help in designing optimal prevention strategies to avoid <it>T. gondii </it>infection.</p

Toxoplasma and coxiella infection and psychiatric morbidity: A retrospective cohort analysis

BACKGROUND: It has been suggested that infection with Toxoplasma gondii is associated with slow reaction and poor concentration, whilst infection with Coxiella burnetii may lead to persistent symptoms of fatigue. METHODS: 425 farmers completed the Revised Clinical Interview Schedule (CIS-R) by computer between March and July 1999 to assess psychiatric morbidity. Samples of venous blood had been previously collected and seroprevalence of T. gondii and C. burnetii was assessed. RESULTS: 45% of the cohort were seropositive for T. gondii and 31% were positive for C. burnetii. Infection with either agent was not associated with symptoms reflecting clinically relevant levels of concentration difficulties, fatigue, depression, depressive ideas or overall psychiatric morbidity. CONCLUSIONS: We do not provide any evidence that infection with Toxoplasma gondii or Coxiella burnetii is associated with neuropsychiatric morbidity, in particular with symptoms of poor concentration or fatigue. However, this is a relatively healthy cohort with few individuals reporting neuropsychiatric morbidity and therefore the statistical power to test the study hypotheses is limited