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. 2025 Aug;30(34):2500069.
doi: 10.2807/1560-7917.ES.2025.30.34.2500069.

Systematic review and modelling of Toxoplasma gondii seroprevalence in humans, Europe, 2000 to 2021

Ingrid Hm Friesema  1 , Helga Waap  1   2 , Arno Swart  1 , Adriana Györke  3 , Delphine Le Roux  4 , Francisco Md Evangelista  5   6 , Furio Spano  7 , Gereon Schares  8 , Gunita Deksne  9 , Maria João Gargaté  10 , Rafael Calero-Bernal  11 , Pikka Jokelainen  12 , Frank Seeber  13 , Jacek Sroka  14 , Anna Lundén  15 , Oda van den Berg  1 , Solveig Jore  16 , Henk J Wisselink  17 , Filip Dámek  4 , Lasse S Vestergaard  18 , Marieke Opsteegh  1
Affiliations

Systematic review and modelling of Toxoplasma gondii seroprevalence in humans, Europe, 2000 to 2021

Ingrid Hm Friesema et al. Euro Surveill. 2025 Aug.

Abstract

BACKGROUNDToxoplasma gondii is a zoonotic protozoan capable of infecting warm-blooded animal species and humans. Although toxoplasmosis presents mostly as mild or asymptomatic infection in immunocompetent individuals, in unborn children and people with weakened immune systems, the disease can be severe with ocular, neurological or multi-systemic manifestations and even death.AIMWe aimed to collate and analyse data on T. gondii seroprevalence in humans to model and compare age-dependent prevalence in geographic regions in Europe.METHODSA systematic review identified 1,822 scientific publications, from which seroprevalence data were extracted from 69 studies. Data were analysed using a Bayesian hierarchical model.RESULTSThe modelling of the seroprevalence indicated the highest incidence rates in eastern (50%) and western (48%) Europe, with the lowest estimates in northern Europe (18%) and the United Kingdom (UK) (18%). Eastern and western Europe were regions where T. gondii infections occurred earliest in life, with half of the population expected to be seropositive by the age of 44 and 47 years, respectively. In contrast, in northern Europe and the UK the modelled median time to infection exceeded 170 years.CONCLUSIONResults of the study provide a robust baseline for future epidemiological research on human T. gondii infections in Europe and may be useful to validate subsequent research, such as risk assessment studies.

Keywords: Europe; Human; Seroprevalence; Systematic review; Toxoplasma gondii.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

This figure shows the curves of seroprevalence of Toxoplasma gondii by age. Separate figures are given for western, eastern, northern, southwestern, southeastern Europe and the United Kingdom (UK). The lines start at 0% seroprevalence and age of 0 years, and confidence bands of the estimates are given. The raw data points are overlaid. The increase in seroprevalence with age is lowest in northern Europe and the UK. Highest increase with age is seen in eastern and western Europe.
Figure 1
Susceptible-Infected-Susceptible (SIS) model fit for age-dependent seroprevalence of Toxoplasma gondii in humans, Europe, 2000–2021
This figure consists of three parts. Panel A shows the posterior distribution of the baseline force of infection as a probability function with additional confidence intervals. Panel B shows the region/country-dependent (y axis) force of infection (x axis). The highest force of infection is seen in eastern Europe, followed by western Europe. Lowest force of infection is seen in northern Europe and the United Kingdom. Panel C is similar to Panel A but shows the inversion rate. The best estimate of the reversion rate exceeds a human lifespan. However, the uncertainty in the estimate is large.
Figure 2
Bayesian hierarchical model outcomes (i.e. posterior probabilities) for the force of infection (λ) and reversion rate (γ) to seronegative status of Toxoplasma gondii in humans, Europe, 2000–2021
See this image and copyright information in PMC

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