Evaluation of diagnostic assays for Toxocara canis infection in humans

Abstract

Toxocara canis (T. canis) is the common roundworm of dogs and other Canidae. Seroprevalence surveys suggest that human infection with this parasite is second only the pinworm in developed countries. Human infection with T. canis is difficult to demonstrate because infecting larvae remain developmentally arrested within the tissues. The current diagnosis of toxocariasis is based on clinical findings correlated with the detection of specific antibodies in the serum. However, many seroresponders show no evidence of clinical infection which questions the relevance of detecting an antibody response to T. canis in these people. T. canis larvae are known to release excretory-secretory antigens in vivo and in vitro. The detection of these antigens in serum potentially provides a marker for current infection. The aim of this research was the development and evaluation of an ELISA capable of detecting circulating ED antigens in human serum. Four assays for ES antigen detection were evaluated using both polyclonal antisera produced against T. canis and a T. canis-specific monoclonal antibody.