Toxocariasis

Abstract

Toxocara canis and Toxocara cati are ubiquitous gastrointestinal parasites of dogs and cats, respectively, worldwide. Due to widespread environmental contamination with their eggs, which are shed in the faeces of infected animals, other hosts such as humans can become infected. In these accidental hosts, the parasites do not develop into adults but remain as larvae, migrating through different organs of the body giving rise to a number of clinical syndromes including visceral larva migrans, ocular larva migrans and neurotoxocariasis. Seroprevalence studies indicate high levels of human exposure worldwide, yet the risks of Toxocara spp. infection remain relatively unknown amongst the general public, and toxocariasis is considered a classic neglected disease. This chapter reviews the life cycles and transmission routes of T. canis and T. cati, along with the different clinical syndromes that manifest during infection, with particular emphasis on neurotoxocariasis and the subsequent implications of this syndrome. Current diagnostic methods are reviewed, and the drawbacks and need for standardisation are discussed, particularly with reference to the present difficulties in distinguishing between T. canis and T. cati infections.