Modelling the risk of food-borne transmission of Toxocara spp. to humans.

Human toxocariasis is a worldwide parasitic disease caused by zoonotic roundworms of the genus Toxocara, which can cause blindness and epilepsy. The aim of this study was to estimate the risk of food-borne transmission of Toxocara spp. to humans in the UK by developing mathematical models created in a Bayesian framework. Parameter estimation was based on published experimental studies and field data from southern England, with qPCR Cq values used as a measure of eggs in spinach portions and ELISA optical density data as an indirect measure of larvae in meat portions. The average human risk of Toxocara spp. infection, per portion consumed, was estimated as 0.016% (95% CI: 0.000-0.100%) for unwashed leafy vegetables and 0.172% (95% CI: 0.000-0.400%) for undercooked meat. The average proportion of meat portions estimated positive for Toxocara spp. larvae was 0.841% (95% CI: 0.300-1.400%), compared to 0.036% (95% CI: 0.000-0.200%) of spinach portions containing larvated Toxocara spp. eggs. Overall, the models estimated a low risk of infection with Toxocara spp. by consuming these foods. However, given the potentially severe human health consequences of toxocariasis, intervention strategies to reduce environmental contamination with Toxocara spp. eggs and correct food preparation are advised.