Comparison of Direct and Indirect Toxoplasma gondii Detection and Genotyping in Game: Relationship and Challenges.

Kaya C Stollberg,Nadja S Bier,Annette Johne,Iryna Hrushetska,Anne Mayer-Scholl,Susanne Diescher,Gereon Schares,Martin H Richter

doi:10.3390/microorganisms9081663

Kaya C Stollberg, Nadja S Bier + Show 6 more

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https://doi.org/10.3390/microorganisms9081663

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Abstract

The importance of game as a source of Toxoplasma gondii (T. gondii) infection in humans is largely unknown. New data on the presence of T. gondii in game hunted in the Federal State of Brandenburg, Germany, were obtained by direct and indirect detection (ELISA). DNA extracted either directly (5 g heart or foreleg muscle, DE) or after acid pepsin digestion (50 g heart, PD) or enriched by magnetic capture (50 g heart, MC) was examined by real-time PCR (qPCR). ELISA revealed seroprevalences of 20% in wild boar (Sus scrofa), 11% in roe deer (Capreolus capreolus) and 6% in red deer (Cervus elaphus). T. gondii DNA was detected by at least one direct detection method in 12% of wild boar, 6% of roe deer, 2% of fallow deer (Dama dama) and 2% of red deer. In both, positive wild boar and roe deer, T. gondii type II specific alleles were the most prevalent, as assessed by PCR-restriction fragment length polymorphism. The highest proportion of positive animals was detected by MC qPCR, followed by PD qPCR with a similar proportion of positive findings. Investigation of 50 g of heart muscle revealed a significantly higher proportion of positive qPCR results than analysis of 5 g (p = 0.048). An association between seropositivity and direct detection was evident in wild boar and roe deer (p < 0.001). Infectivity of T. gondii DNA–positive samples was confirmed by bioassay (4/4), providing evidence that game could represent a relevant source of viable T. gondii posing a risk for human infection.

Highlights

German Federal Institute for Risk Assessment (BfR), Department for Safety in the Food Chain, National Reference Laboratory for Toxoplasmosis, Institute of Epidemiology, Friedrich-Loeffler-Institut (FLI), German Federal Institute for Risk Assessment (BfR), Department for Biological Safety, 12277 Berlin, Germany; Abstract: The importance of game as a source of Toxoplasma gondii (T. gondii) infection in humans is largely unknown
During the hunting seasons 2019/2020 and 2020/2021, T. gondii–specific antibodies were detected in 14.3% (18/126; 95% CI: 8.7–21.6%) of wild boar, 6.8% (4/59; 95% CI: 1.9–16.5%) of roe deer and 5.6% (1/18; 95% CI: 0.1–27.3%) of red deer
No T. gondii–specific antibodies were found in fallow deer (0/80; 95% CI: 0–4.5%)

Summary

Introduction

ELISA revealed seroprevalences of 20% in wild boar (Sus scrofa), 11% in roe deer (Capreolus capreolus) and. T. gondii DNA was detected by at least one direct detection method in 12% of wild boar, 6% of roe deer, 2% of fallow deer (Dama dama) and 2% of red deer. Positive wild boar and roe deer, T. gondii type II specific alleles were the most prevalent, as assessed by PCR-restriction fragment length polymorphism. An association between seropositivity and direct detection was evident in wild boar and roe deer (p < 0.001). It is the cause of toxoplasmosis, one of the most common parasitic zoonoses worldwide [1]. The general assumption is that one-third of the worldwide human population is chronically infected with the parasite [2]. While acquired toxoplasmosis is mostly asymptomatic in immunocompetent persons, it can cause a more severe or even fatal course of disease in immunocompromised individuals, with chorioretinitis, encephalitis and pneumonia as potential outcomes [5,6]

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