Probable neuroimmunological link between Toxoplasma and cytomegalovirus

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Sorry posted wrong title in previous post, here is the toxo/CMV article

Nelly

BMC Infectious Diseases 2005, 5:54 doi:10.1186/1471-2334-5-54Published 6 July 2005Abstract (provisional) BackgroundRecently, a negative association between Toxoplasma-infection and noveltyseeking was reported. The authors suggested that changes of personalitytrait were caused by manipulation activity of the parasite, aimed atincreasing the probability of transmission of the parasite from anintermediate to a definitive host. They also suggested that low noveltyseeking indicated an increased level of the neurotransmitter dopamine in thebrain of infected subjects, a phenomenon already observed in experimentallyinfected rodents. However, the changes in personality can also be just abyproduct of any neurotropic infection. Moreover, the association between apersonality trait and the toxoplasmosis can even be caused by an independentcorrelation of both the probability of Toxoplasma-infection and thepersonality trait with the third factor, namely with the size of livingplace of a subject. To test these two alternative hypotheses, we studied theinfluence of another neurotropic pathogen, the cytomegalovirus, on thepersonality of infected subjects, and reanalyzed the original data after theeffect of the potential confounder, the size of living place, wascontrolled.MethodsIn the case-control study, 533 conscripts were tested for toxoplasmosis andpresence of anti-cytomegalovirus antibodies and their novelty seeking wasexamined with Cloninger's TCI questionnaire. Possible association betweenthe two infections and TCI dimensions was analyzed.ResultsThe decrease of novelty seeking is associated also with cytomegalovirusinfection. After the size of living place was controlled, the effect oftoxoplasmosis on novelty seeking increased. Significant difference innovelty seeking was observed only in the largest city, Prague.ConclusionsToxoplasma and cytomegalovirus probably induce a decrease of noveltyseeking. As the cytomegalovirus spreads in population by direct contact (notby predation as with Toxoplasma), the observed changes are the byproduct ofbrain infections rather than the result of manipulation activity of aparasite. Four independent lines of indirect evidence, namely directmeasurement of neurotransmitter concentration in mice, the nature ofbehavioral 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 arole in behavioral changes of infected hosts. http://www.biomedcentral.com/1471-2334/5/54/abstract