Folia Parasitologica, vol. 57 (2010), issue 2

Influence of latent toxoplasmosis on the phenotype of intermediate hosts

Jaroslav Flegr

Folia Parasitologica 57[2] 81-87 (2010) | 10.14411/fp.2010.010

Manipulation of host behaviour by Toxoplasma gondii: what is the minimum a proposed proximate mechanism should explain?

Ajai Vyas, Robert Sapolsky

Folia Parasitologica 57[2] 88-94 (2010) | 10.14411/fp.2010.011

The behavioural manipulation hypothesis posits that parasites can change the behaviour of hosts to increase the reproductive fitness of the parasite. The protozoan parasite Toxoplasma gondii fits this description well. Sexual reproduction occurs in the cat intestine, from which highly stable oocysts are excreted in faeces. Grazing animals, including rodents, can then ingest these oocysts. The parasite has evolved the capacity to abolish the innate fear that rodents have of the odours of cats, and to convert that fear into an attraction. This presumably increases the likelihood of the rodent being predated, thereby completing the parasite's life...

Toxoplasma gondii-altered host behaviour: clues as to mechanism of action

Joanne P. Webster, Glenn A. McConkey

Folia Parasitologica 57[2] 95-104 (2010) | 10.14411/fp.2010.012

A convincing body of evidence now exists, from both human and animal studies, and encompassing epidemiological to experimental, to indicate that the common protozoan Toxoplasma gondii can cause specific behavioural changes in its host. Such behavioural alterations are likely to be the product of strong selective pressures for the parasite to enhance transmission from its intermediate host reservoir, primarily rodent, to its feline definitive host, wherein sexual reproduction can occur and the parasite's life cycle completed. Here we consider what the available data to date may reveal about the potential mechanisms involved, the future research...

Toxoplasmosis as a cause for behaviour disorders - overview of evidence and mechanisms

Abebaw Fekadu, Teshome Shibre, Anthony J. Cleare

Folia Parasitologica 57[2] 105-113 (2010) | 10.14411/fp.2010.013

Background - There is growing interest in the role of microbial agents in the causation of psychiatric disorders. The neurotropic protozoan parasite Toxoplasma gondii is one of the main candidates and has been associated with various psychiatric conditions, including schizophrenia. Methods - A narrative review of the literature from the main medical databases (Medline, PubMed, PsycINFO), Google Scholar and Google using combinations of applicable terms. Results - T. gondii affects the brain in both the acute and the latent stages of infection causing apparent brain pathologies in infected rodents and both immuno-compromised and immuno-competent...

Potential solutions to problems posed by the offspring sex ratios of people with parasitic and viral infections

William H. James

Folia Parasitologica 57[2] 114-120 (2010) | 10.14411/fp.2010.014

I have hypothesized that mammalian offspring sex ratios (proportions male at birth) are partially controlled by the hormone levels of both parents around the time of conception. Recently data have been published (privately) which impugn suggestions of mine (based on that hypothesis) relating to the offspring sex ratios of people who are carriers of hepatitis B virus; and (publicly) to hormone profiles of women who are infected with the protozoan parasite Toxoplasma gondii. Here these data are reviewed in the light of data on offspring sex ratios of people infected with hepatitis C, and cytomegalovirus and T. gondii; and of mice with T....

The role of latent toxoplasmosis in the aetiopathogenesis of schizophrenia - the risk factor or an indication of a contact with cat?

Pelin Yuksel, Nihat Alpay, Cahit Babur, Reha Bayar, Suat Saribas, Ali Riza Karakose, Cana Aksoy, Mustafa Aslan, Seyfi Mehmetali, Selcuk Kilic, Ibrahim Balcioglu, Ozlem Hamanca, Ahmet Dirican, Omer Kucukbasmaci, Ali Oner, Muzeyyen Mamal Torun, Bekir Kocazeybek

Folia Parasitologica 57[2] 121-128 (2010) | 10.14411/fp.2010.015

We assessed IgG antibody to Toxoplasma gondii in 300 inpatients with schizophrenia (SG), 150 outpatients with anxiety and depressive disorders (PCG), and 150 healthy blood donors (HCG). Seropositivity rates were 60.7% for SG, 36.7% for PCG, and 45.3% for HCG (p<0.001). The seropositivity rate for anti-Toxoplasma IgG antibodies in SG was significantly higher that in PCG (X2=23.11, OR=2.66, p=0.001) and HCG (X2=9.52, OR=1.86, p=0.002). Among SG, 85% of those who reported close cat contact had IgG antibodies to T. gondii. Close cat contacts were reported by 59% of SG, 6% of PCG, and 9% of HCG (p<0.001)....

The diagnosis of a personality disorder increases the likelihood for seropositivity to Toxoplasma gondii in psychiatric patients

Dunja Hinze-Selch, Walter Däubener, Sükran Erdag, Sibylle Wilms

Folia Parasitologica 57[2] 129-135 (2010) | 10.14411/fp.2010.016

Individuals serologically positive for the chronic infection with the parasite Toxoplasma gondii (TG) display certain personality traits differently from uninfected individuals. Experimental data in mice demonstrate that TG infection modulates behaviour. However, psychiatric patients with a personality disorder have not yet been investigated systematically. In our sample containing 896 psychiatric inpatients with the primary diagnoses of schizophrenia, major depression, schizoaffective or bipolar disorder and 214 psychiatrically unaffected controls (same geographic region, sampled during same time period) we analysed for effects of the additional...

Pattern of money allocation in experimental games supports the stress hypothesis of gender differences in Toxoplasma gondii-induced behavioural changes

Jitka Lindová, Aleš A. Kuběna, Hana Šturcová, Romana Křivohlavá, Martina Novotná, Anna Rubešová, Jan Havlíček, Petr Kodym, Jaroslav Flegr

Folia Parasitologica 57[2] 136-142 (2010) | 10.14411/fp.2010.017

Latent toxoplasmosis has been previously found to cause behavioural and personality changes in humans, which are specific for each gender. Here we tested the stress hypothesis of these gender differences based on the assumption that latent toxoplasmosis causes long-term subliminal stress. In line with this hypothesis, the gender difference will appear specifically in situations with interpersonal context because in contrast to the typical individualistic coping style of men, women have a tendency to express elevated prosocial behaviour under stress. Altogether 295 biology students (29/191 females and 27/104 males infected by T. gondii) played...

The influence of RhD phenotype on toxoplasmosis- and age-associated changes in personality profile of blood donors

Jaroslav Flegr, Martina Novotná, Anna Fialová, Petra Kolbeková, Zdeňka Gašová

Folia Parasitologica 57[2] 143-150 (2010) | 10.14411/fp.2010.018

Toxoplasma gondii, a parasite infecting 20-60% of humans in various countries, influences the behaviour of infected animal and human hosts. Infected human subjects have changes in several of Cattell's and Cloninger's personality factors. Recently, three independent studies have shown that Rh-positive subjects are protected against the T. gondii-induced changes of reaction times and increased risk of traffic accidents. Here we searched for evidence of similar effects of RhD phenotype on toxoplasmosis- or aging-associated changes in the personality profile of about 302 blood donors. We found that Rh-positive and Rh-negative subjects responded...

Toxoplasma gondii strain-dependent effects on mouse behaviour

Geetha Kannan, Krisztina Moldovan, Jian-Chun Xiao, Robert H. Yolken, Lorraine Jones-Brando, Mikhail V. Pletnikov

Folia Parasitologica 57[2] 151-155 (2010) | 10.14411/fp.2010.019

Toxoplasma gondii reportedly manipulates rodent behaviour to increase transmission to its definitive feline host. We compared the effects of mouse infection by two Type II strains of T. gondii, Prugniaud (PRU) and ME49, on attraction to cat odour, locomotor activity, anxiety, sensorimotor gating, and spatial working and recognition memory 2 months post-infection (mpi). Attraction to cat odour was reassessed 7 mpi. At 2 mpi, mice infected with either strain exhibited significantly more attraction to cat odour than uninfected animals did, but only PRU-infected mice exhibited this behaviour 7 mpi. PRU-infected mice had significantly greater...

In Memoriam - Dr. Jiří Lom: October 24, 1931 - April 9, 2010

Vladimír Bukva, Libor Grubhoffer

Folia Parasitologica 57[2] 156 (2010) | 10.14411/fp.2010.020