Assessing food-borne risks of Toxocara infection in support of public health and food quality assurance

Toxocariasis, caused by infection with the zoonotic nematode parasite Toxocara spp., is an increasing public health concern. Evidence for clinical and subclinical impacts, e.g. through neurological and respiratory disease and impaired cognitive development, is increasing (Ma et al. 2018 Lancet Infectious Diseases 18, E14-E24). High seroprevalence suggests a significant burden of disease (Rostami et al. 2019 Inf Gen Evol 74, UNSP 104002). Infection is supposed to be mostly from contact with soil contaminated by eggs shed in the faeces of infected dogs, cat and foxes. A wide range of animals species can also act as transport hosts, and this includes livestock. Up to 47% of sheep in the UK, for example, have tested positive for specific anti-Toxocara antibodies (Lloyd et al. 2006 Vet Parasitol 137, 269-272). This raises the possibility of meat-borne transmission. Beyond some case reports linked to consumption of undercooked bird liver, however, this route has largely been ignored in public health risk assessments. Furthermore, contamination of vegetables could occur but evidence of the level of hazard has not been published