Folia Parasitologica 68:005 (2021) | DOI: 10.14411/fp.2021.005

Latent toxoplasmosis and vitamin D concentration in humans: three observational studies

Šárka Kaňková^1,2, Marie Bičíková³, Ludmila Máčová³, Jana Hlaváčová¹, Kateřina Sýkorová¹, Dobroslava Jandová⁴, Jaroslav Flegr^1,2

¹ Department of Philosophy and History of Science, Faculty of Science, Charles University, Prague, Czech Republic;

² Applied Neurosciences and Brain Imaging, National Institute of Mental Health, Klecany, Czech Republic;

³ Institute of Endocrinology, Prague, Czech Republic;

⁴ Third Faculty of Medicine of Charles University, Prague, Czech Republic

Numerous recent studies show that vitamin D deficiency potentiates various chronic physical and psychiatric disorders and diseases. It has been shown that a similar range of disorders is also associated with latent infection with Toxoplasma gondii (Nicolle et Manceaux, 1908). For instance, among cancer, diabetes and schizophrenia patients, we find a higher prevalence of both toxoplasmosis and vitamin D deficiency. Theoretically, therefore, vitamin D deficiency could be the missing link between toxoplasmosis and these disorders. We tested this hypothesis by searching for decreased vitamin D levels in the serum of subjects infected with T. gondii (furthermore called Toxoplasma-infected subjects) in two cross-sectional and one case-control study. Results of the first cross-sectional study (N = 72) suggest that Toxoplasma-infected neurasthenic patients have non-significantly lower levels of calcidiol than Toxoplasma-free patients (study A: P = 0.26 in women, P = 0.68 in men). However, two other studies (study B: N = 400; study C: N = 191) showed a non-significantly higher concentration of vitamin D in Toxoplasma-infected subjects than in Toxoplasma-free subjects both in men (study B: P = 0.70, study C: P = 0.55) and in women (study B: P = 0.64, study C: P = 0.12). Taken together, our preliminary results thus do not support the hypothesis that toxoplasmosis could be associated with vitamin D decrease.

Keywords: Toxoplasma gondii, calcidiol, depression, mental disorders, schizophrenia.

Received: August 7, 2020; Revised: October 28, 2020; Accepted: November 11, 2020; Published online: February 12, 2021  Show citation