In human
toxocariasis, there are few approaches using immunological markers for diagnosis and therapeutic assessment. An immunoblot (IB) assay using excretory-secretory Toxocara canis
antigen was standardized for monitoring
IgG,
IgE and
IgA antibodies in 27 children with
toxocariasis (23 visceral, three mixed visceral and ocular, and one ocular form) for 22-116 months after
chemotherapy. IB sensitivity was 100% for
IgG antibodies to bands of molecular weight 29-38, 48-54, 95-116, 121-162, >205 kDa, 80.8% for
IgE to 29-38, 48-54, 95-121, > 205 kDa, and 65.4% for
IgA to 29-38, 48-54, 81-93 kDa. Candidates for diagnostic markers should be
IgG antibodies to bands of low molecular weight (29-38 and 48-54 kDa). One group of patients presented the same antibody reactivity to all bands throughout the follow-up study; in the other group,
antibodies decayed partially or completely to some or all bands, but these changes were not correlated with time after
chemotherapy. Candidates for monitoring patients after
chemotherapy may be
IgG antibodies to > 205 kDa fractions,
IgA to 29-38, 48-54, 81-93 kDa and
IgE to 95-121 kDa. Further identification of
antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of
toxocariasis.