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Thesis summary

Toxoplasma gondii (T. gondii) is a single-celled parasite, which has a worldwide distribution and can infect virtually all warm-blooded animals. Toxoplasmosis ranks in the top 3 when comparing the disease burden of 14 foodborne diseases in the Netherlands and Europe.

Quantitative microbial risk assessment (QMRA) is a source attribution method, which aggregates all available data on different aspects to compare the importance of different sources of infection. This thesis focuses on the assessment of relative attribution of meat products and soil to human T. gondii infection in the Netherlands by using QMRA models. In addition, the QMRA model of meat-borne T. gondii infection from the Netherlands was adapted for the mainland of China, where consumers have different consumption habits.

In the Netherlands, a raw processed beef product was predicted to contribute most to the infections via meat. For the mainland of China, the model identified pork as the main source. The importance of meat products differs, for example, based on differences in the prevalence of infection in livestock, and consumption and preparation habits. Results from the developed model for T. gondii infections of oocyst exposure via soil indicate this environmental route could be more important than transmission via meat. However, both QMRA models overestimated the number of infections when compared to epidemiological data. The models need to be updated regularly when new or missing data become available.

The findings in this thesis can aid science-based decision-making on where to target interventions, thereby, in the end, reducing the disease burden of toxoplasmosis.