Detection and identification of Toxocara canis DNA in bronchoalveolar lavage of infected mice using a novel real-time PCR

Abstract

Toxocarosis is a zoonosis with worldwide distribution caused by Toxocara spp. of dogs and cats. In humans, diagnosis relies mainly on detection of parasite-specific antibodies. Although serological assays in current use have defined sensitivity and specificity, the problem of cross-reactivity still remains, particularly in areas of endemic polyparasitism. Microscopic detection of the parasite in tissue biopsies is not recommended for diagnosis because larvae can be difficult to locate, and finding the parasite eggs in faeces is not applicable since the larvae do not develop to the adult stage in the human host. In this study we describe a novel real-time PCR (‘Nemo-PCR’) that, in combination with DNA sequencing, allows the detection and identification of Toxocara canis and other nematodes in the Superfamily Ascaridoidea. Results indicate that this approach can detect Toxocara spp. DNA in bronchoalveolar lavage (BAL) of experimentally-infected mice. For diagnostic purposes further studies are necessary to evaluate this assay including testing human BAL fluid. The availability of such a direct assay would improve diagnosis of toxocarosis particularly for patients with pulmonary signs and symptoms.