Human cystic echinococcosis is a zoonosis occurring due to dogs handling and exposure to
Echinococcus granulosus ova in their stools being an accidental intermediate host. Serology
remains the only sure and important tool to diagnose this disease. We aimed to improve the
detection of circulating antigen by sandwich ELISA through its binding to gold nanoparticle
and proving the role of minute nanoparticles in serodiagnosis. Gold nanoparticles (AuNPs)
were employed for the capture of the antigens of protoscolices (pAg) in the patient's serum by
sandwich ELISA. Cross-reactivity for antigens from Hymenolepis nana, Entrobius vermicularis,
and Fasciola gigantica was ruled out by using anti-protoscolices polyclonal IgG antibodies
(ppAb). Antigen of sonicated protoscolices which were removed from camel lung
cysts, was purified and injected to a New-zealand white rabbit giving ppAb which then loaded
on AuNPs being used as a diagnostic indicator for circulating pAg by both sandwich ELISA
and nanogold sandwich ELISA techniques. Nanogold sandwich ELISA was able to give positive
results with 96.3% of hydatid patients and 5% of non-hydatid patients while sandwich
ELISA showed 81.4% and 20% positive cases of the same groups respectively. The sensitivity
and specificity of nanogold sandwich ELISA were 96.3% & 95% against 81.5% & 80% for
those of sandwich ELISA respectively. The conjugation of AuNPs to anti-Echinococcus IgG
antibodies seems to be beneficial to increase PPV, NPV, and efficiency and reduce the overall
cost of the assay as less antibody was needed.