The latest Paper of the Month for Parasitology is “Brain Food: rethinking food-borne toxocariasis” and is freely available.

Toxocara canis and T. cati are parasitic roundworms, primarily affecting dogs, cats and foxes. When these animals are infected, they pass Toxocara eggs in their faeces, which then contaminate the environment and can survive there for long periods. In around a month, the larvae contained in these eggs develop to become infective and are ready to be ingested by another host. If the new host is not a dog, cat or fox, the larvae migrate out of the gut and around the body to settle in various tissues. In humans, infection with Toxocara (or ‘toxocariasis’) is often not symptomatic, however severe disease can result from the larval migration, including various brain disorders, blindness and organ damage.

Despite recognition of its clinical impact, and recent estimates of over a billion people infected with Toxocara worldwide, toxocariasis remains a much-neglected disease. There is still a great deal we don’t yet know about the epidemiology of this parasite. Whilst it is widely accepted that humans can become infected with Toxocara by accidentally ingesting eggs from contaminated soil, little is known about food-borne transmission. We eat vegetables grown in soil, so if consumed raw and unwashed, could we also be eating Toxocara eggs? And with the potential for eggs to be eaten by grazing livestock, could contaminated meat tissues transmit Toxocara larvae to humans if not cooked sufficiently?

This review highlights the key knowledge gaps in our understanding of food-borne toxocariasis, assessing the evidence for this route of transmission by means of published human cases, antibody studies and the recovery of Toxocara from foods.  The ability of current food safety measures to prevent toxocariasis is discussed, alongside future research avenues to determine appropriate prevention strategies for this overlooked, but potentially significant issue. 

Toxocara sp. eggs, 400x magnification, 50 μm scale bar (© Lance Wheeler, 2018 | Photographer: Lance Wheeler | Owner of Specimen: Texas A&M College of Veterinary Medicine, Department of Veterinary Pathobiology)

The paper “Brain food: rethinking food-borne toxocariasis” by Sara R. Healy, Eric R. Morgan, Joaquin M. Prada and Martha Betson, published in Parasitology, is freely available.