From the Guidelines
Serological tests, specifically the enzyme-linked immunosorbent assay (ELISA) followed by a confirmatory test such as immunoblotting or indirect hemagglutination assay (IHA), are essential for diagnosing hydatid disease, as recommended for donors from areas of endemicity with suggestive imaging 1.
Diagnosis Approach
The diagnostic approach for hydatid disease involves:
- Initial screening with ELISA due to its high sensitivity
- Confirmation with immunoblotting or IHA to improve diagnostic accuracy
- Detection of specific antibodies against Echinococcus antigens, particularly IgG antibodies, in the patient's serum
Important Considerations
- False negatives can occur in cases of isolated pulmonary cysts, early infection, or immunocompromised patients
- Cross-reactivity with other helminthic infections may cause false positives
- Serological results should always be interpreted alongside clinical findings and imaging studies such as ultrasound, CT, or MRI
Additional Diagnostic Information
- Testing for circulating Echinococcus antigens using AgB ELISA may provide additional diagnostic information in endemic areas or when diagnostic uncertainty persists
- Serological monitoring can also be valuable for post-treatment follow-up, with declining antibody titers generally indicating successful treatment According to the provided evidence, organ affected by hydatidosis should not be used in transplantation except if cyst is very localized, inactive or calcified and may be radically excised 1.
From the Research
Serological Tests for Hydatid Disease
- Various serological tests have been developed for the diagnosis of hydatid disease, including ELISA, IHA, and IgE and IgG enzyme-linked immunosorbent assay (ELISA) tests 2.
- The sensitivity and specificity of these tests vary, with specific IgG ELISA AgB (antigen B-rich fraction) being the most sensitive test (96.5%) and specific IgE ELISA (24.1%) and IEP (25.8%) being the least sensitive tests 2.
- The use of purified antigens, such as the antigen-B-rich fraction, has been shown to improve the sensitivity and specificity of ELISA tests 2, 3.
Evaluation of ELISA and IHA Tests
- Studies have evaluated the validity of ELISA and IHA tests for the serological diagnosis of hydatidosis, with sensitivity and specificity rates ranging from 73.6% to 96.7% and 83.3% to 98.3%, respectively 4, 5.
- The combination of multiple tests, such as ELISA and IHA, has been shown to improve the sensitivity of diagnosis, with a combined sensitivity of up to 94.7% 5.
Antigens and Diagnostic Markers
- Antigen B (AgB) and its subunits, such as the 8 kDa subunit, have been identified as promising antigens for the diagnosis of hydatid disease 3.
- The detection of specific antibodies, such as IgG subclasses, has also been shown to improve the efficacy of immunodiagnostic tests, with IgG2 and IgG4 being considered good markers for diagnosis and IgG4 being a suitable marker for follow-up of patients 3.