Clinical pathology of larval toxocariasis.

Human toxocariasis is a worldwide helminth zoonosis caused by roundworms of the genus Toxocara. Toxocariasis is the most common helminth infection in many countries. Disease caused by Toxocara can be classified into five clinical forms: generalised, neurological, ocular, covert, and asymptomatic. The clinical pathology of toxocariasis largely depends on the form of infection, the intensity of the infection, the larvae localisation, and the age of the host. Because histological and molecular examination of toxocariasis is limited by difficulties in obtaining material to analyse, clinical diagnosis is often based on nonspecific tests, such as the detection of eosinophilia and hyperimmunoglobulinemia E (Hyper-IgE). Specific analysis uses an initial ELISA test to detect anti-Toxocara IgG and requires confirmation for all positive results via Western blot. This strategy does not distinguish between actual and recent infections, making the monitoring of disease a challenge for clinicians. Additional research will be required to distinguish active disease from the presence of recent infection.