Large-scale study of Toxoplasma and Cytomegalovirus shows an association between infection and serious psychiatric disorders

Kristoffer Sølvsten Burgdorf, Betina B. Trabjerg, Marianne Giørtz Pedersen, Janna Nissen, Karina Banasik, Ole Birger Pedersen, Erik Sørensen, Kaspar René Nielsen, Margit Hørup Larsen, Christian Erikstrup, Peter Bruun-Rasmussen, David Westergaard, Lise Wegner Thørner, Henrik Hjalgrim, Helene Martina Paarup, Søren Brunak, Carsten B. Pedersen, E. Fuller Torrey, Thomas Werge, Preben Bo MortensenRobert H. Yolken, Henrik Ullum

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Background: Common infectious pathogens have been associated with psychiatric disorders, self-violence and risk-taking behavior. Methods: This case-control study reviews register data on 81,912 individuals from the Danish Blood Donor Study to identify individuals who have a psychiatric diagnosis (N = 2591), have attempted or committed suicide (N = 655), or have had traffic accidents (N = 2724). For all cases, controls were frequency matched by age and sex, resulting in 11,546 participants. Plasma samples were analyzed for immunoglobulin G (IgG) antibodies against Toxoplasma gondii and cytomegalovirus (CMV). Results: T. gondii was detected in 25·9% of the population and was associated with schizophrenia (odds ratio [OR], 1·47; 95% confidence interval [CI], 1·03–2·09). Accounting for temporality, with pathogen exposure preceding outcome, the association was even stronger (IRR, 2·78; 95% CI, 1·27–6·09). A very weak association between traffic accident and toxoplasmosis (OR, 1·11; 95% CI, 1·00–1·23, p = 0.054) was found. CMV was detected in 60·8% of the studied population and was associated with any psychiatric disorder (OR, 1·17; 95% CI, 1·06–1·29), but also with a smaller group of neurotic, stress-related, and somatoform disorders (OR, 1·27; 95% CI, 1·12–1·44), and with attempting or committing suicide (OR, 1·31; 95% CI, 1·10–1·56). Accounting for temporality, any psychiatric disorder (IRR, 1·37; 95% CI, 1·08–1·74) and mood disorders (IRR, 1·43; 95% CI, 1·01–2·04) were associated with exposure to CMV. No association between traffic accident and CMV (OR, 1·06; 95% CI, 0·97–1·17) was found. Conclusions: This large-scale serological study is the first study to examine temporality of pathogen exposure and to provide evidence of a causal relationship between T. gondii and schizophrenia, and between CMV and any psychiatric disorder.

Original languageEnglish (US)
Pages (from-to)152-158
Number of pages7
JournalBrain, Behavior, and Immunity
StatePublished - Jul 2019


  • Antibodies
  • Cytomegalovirus
  • Infection
  • Parasite, psychiatric disorders
  • Serology
  • Suicide
  • Toxoplasma gondii
  • Toxoplasmosis
  • Traffic accidents

ASJC Scopus subject areas

  • Immunology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience


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