Special Issue. Effects of Latent Toxoplasmosis: Three Decades of Studies
Special Issue: Toxoplasma gondii and suicidal behaviour: discovery, cross-diagnostic confirmation and pathway exploration
Teodor T. Postolache
Folia Parasitologica 72:025 (2025) | DOI: 10.14411/fp.2025.025 
Our team's discovery of the link between chronic "latent" infection with Toxoplasma gondii (Nicolle et Manceaux, 1908) and suicidal behaviour, and our subsequent cross-diagnostic confirmatory work and mechanistic extensions, evolved from our neuroimmunology studies on affective and behavioural dysregulation exacerbated by allergic sensitisation and allergen exposure. Another root was studying behavioural changes and cytokine gene expression in the brain of rodents sensitised and exposed to aeroallergens. We "piggy-backed" our project funded to study coupling between aeroallergen sensitisation and exposure in patients with recurrent mood...
Special Issue: Association between type-2 diabetes and Toxoplasma gondii seropositivity: a systematic review and meta-analysis
Ashley Catchpole, Brinley N. Zabriskie, Bradley Embley, Hannah Kharazi, Rachelle Clarke, Grace Templeton, Christopher Hunt, Shawn D. Gale, Dawson W. Hedges
Folia Parasitologica 72:024 (2025) | DOI: 10.14411/fp.2025.024
A metabolic disease resulting in elevated blood glucose levels, type-2 diabetes affects approximately 462 million people globally. Although its prevalence appears to be increasing, type-2 diabetes has been associated with various potentially preventable risk factors, including infectious diseases. The protozoal infection with Toxoplasma gondii (Nicolle et Manceaux, 1908) has been associated with type-2 diabetes in two previous meta-analyses. Since the publication of the last meta-analysis supporting an association between type-2 diabetes and T. gondii, several new primary studies have investigated this association. In this meta-analysis,...
Special Issue: Chronic inflammation in pregnant women with latent toxoplasmosis and explanation of discordant results of serological tests for toxoplasmosis
Jana Ullmann, Jaroslav Flegr, Kamila Nouzová, Josef Včelák, ©árka Kaňková
Folia Parasitologica 72:021 (2025) | DOI: 10.14411/fp.2025.021
Toxoplasma gondii (Nicolle et Manceaux, 1908), an intracellular parasite that causes toxoplasmosis, infects a third of the human population. Latent toxoplasmosis has been linked to altered immune responses, including elevated proinflammatory cytokines. In early pregnancy, the immune system adapts to balance inflammation and foetal tolerance. This study assessed whether pregnant women in the first trimester infected with Toxoplasma gondii have different cytokine levels than uninfected women. This study also examined whether women with discordant test results for toxoplasmosis represent a distinct group or a mixed group composed...
Special Issue: Who makes the decisions? Uncovering the evolutionary implications and clinical applications of Toxoplasma gondii's Fatal Feline Attraction
Joanne P. Webster
Folia Parasitologica 72:016 (2025) | DOI: 10.14411/fp.2025.016
Here I recount my research journey on the coccidian protist Toxoplasma gondii (Nicolle et Manceaux, 1908), a ubiquitous parasite capable of infecting all warm-blooded animals as intermediate or secondary host, but with only members of the Felidae as its definitive host. I describe my initial studies into its epidemiology and persistence within the UK, and how this led on to a series of biologically and ethically appropriate studies into T. gondii's apparent specific manipulation of its rat intermediate host to facilitate transmission to its feline definitive host. I then describe how this prompted searches into the potential mechanisms...
Special Issue: Re-assessing host manipulation in Toxoplasma: the underexplored role of sexual transmission - evidence, mechanisms, implications
Ashkan Latifi, Jaroslav Flegr, ©árka Kaňková
Folia Parasitologica 72:015 (2025) | DOI: 10.14411/fp.2025.015
Latent infection with Toxoplasma gondii (Nicolle et Manceaux, 1908) has been repeatedly correlated with behavioural and physiological changes in both humans and animals. While classically regarded as a parasite transmitted via ingestion or vertical (transplacental) transmission, accumulating evidence suggests that sexual transmission may also contribute to its epidemiology. This review explores the hypothesis that some behavioural effects of toxoplasmosis - especially those related to attraction, sexual activity, and mate choice - may have evolved to facilitate sexual transmission of the parasite. We summarise findings from animal models and...
Special Issue: Thirty years of studying latent toxoplasmosis: behavioural, physiological, and health insights
Jaroslav Flegr
Folia Parasitologica 72:005 (2025) | DOI: 10.14411/fp.2025.005
In this article, I recount the journey of discovering the effects of latent toxoplasmosis on human psychology, behaviour, morphology, and health as I observed it from the closest perspective over the past 30+ years, during which our laboratory has been intensely focused on this research. I trace how we moved from the initial observations of differences between infected and uninfected individuals in certain personality traits to the systematic study of similar differences in behaviour, both in the laboratory and in everyday life, as well as in physiological and even morphological traits. This eventually led us to investigate the causal relationships...
Special Issue: Toxoplasma gondii, suicidal behaviour and suicide risk factors in US Veterans enrolled in mental health treatment
Teodor T. Postolache, Erica Duncan, Poyu Yen, Eileen Potocki, Meghan Barnhart, Amanda Federline, Nicholas Massa, Aline Dagdag, Joshua Joseph, Abhishek Wadhawan, Colt D. Capan, Cameron Forton, Christopher A. Lowry, Heidi K. Ortmeyer, Lisa A. Brenner
Folia Parasitologica 72:002 (2025) | DOI: 10.14411/fp.2025.002
Markers of chronic infection Toxoplasma gondii (Nicolle et Manceaux, 1908) have been associated with suicidal self-directed violence (SSDV). We present the results of the first study relating T. gondii IgG serology with suicide attempts and suicidal ideation in United States Veterans, known to have higher suicide rates than members of the general population. We also related T. gondii serology to SSDV risk factors, including valid and reliable measures of trait impulsivity, aggression, self-reported depression, and sleep disturbance. We recruited 407 Veterans enrolled at three Veterans Affairs Medical Centers with mean (S.D.)...
Special Issue: Nuts and bolts of the behavioural manipulation by Toxoplasma gondii
Ajai Vyas
Folia Parasitologica 71:017 (2024) | DOI: 10.14411/fp.2024.017
In this review, I take the first-person perspective of a neuroscientist interested in Toxoplasma gondii (Nicolle et Manceaux, 1908). I reflect on the value of behavioural manipulation as a perturbation tool to understand the organisation of behaviour within the brain. Toxoplasma gondii infection reduces the aversion of rats to the olfactory cues of cat presence. This change in behaviour is one of the often-discussed exemplars of host-parasite coevolution, culminating in the manipulation of the host behaviour for the benefit of the parasite. Such coevolution also means that we can use host-parasite systems as tools to derive fundamental...
Special Issue: The linking of toxoplasmosis and schizophrenia
Edwin Fuller Torrey
Folia Parasitologica 71:016 (2024) | DOI: 10.14411/fp.2024.016
Toxoplasmosis is caused by Toxoplasma gondii (Nicolle et Manceaux, 1908), a coccidian protist (Apicomplexa). It has a strong predilection for infecting the central nervous system. Researchers have therefore investigated its association with several neurological and psychiatric disorders, including Alzheimer's disease, attention-deficit hyperactivity disorder, autism, bipolar disorder, cerebral palsy, depression, Guillain-Barre syndrome, multiple sclerosis, obsessive compulsive disorder, Parkinson's disease, personality disorders, and schizophrenia. Among these disorders the strongest evidence for a role of T. gondii exists for psychosis...