Modelling the risk of food-borne transmission of <i>Toxocara</i> spp. to humans

Human toxocariasis is a worldwide parasitic disease caused by zoonotic roundworms of the genus <i>Toxocara</i>, which can cause blindness and epilepsy. The aim of this study was to estimate the risk of food-borne transmission of <i>Toxocara</i> 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 <i>Toxocara</i> 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 <i>Toxocara</i> 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 <i>Toxocara</i> spp. eggs. Overall, the models estimated a low risk of infection with <i>Toxocara</i> spp. by consuming these foods. However, given the potentially severe human health consequences of toxocariasis, intervention strategies to reduce environmental contamination with <i>Toxocara</i> spp. eggs and correct food preparation are advised.