What are the best serological tests for diagnosing amoebic liver abscess, such as Enzyme-Linked Immunosorbent Assay (ELISA) or Enzyme Immunoassay (EIA)?

From the Guidelines

The best serological diagnosis for amoebic liver abscess is Indirect Haemagglutination, which has over 90% sensitivity. This is based on the study by 1, which recommends performing amoebic serology in patients with a neutrophil leucocytosis of >10 109 /L, raised inflammatory markers, and deranged liver function tests.

Key Points to Consider

• Indirect Haemagglutination has high sensitivity for amoebic liver abscess, making it a reliable diagnostic tool.
• Faecal microscopy is usually negative in patients with ALA, so serological testing is preferred.
• An abdominal ultrasound may be indicated to support the diagnosis.
• While Enzyme-Linked Immunosorbent Assay (ELISA) and Enzyme Immunoassay (EIA) are also useful tests, the study by 1 specifically mentions Indirect Haemagglutination as a sensitive test for amoebic liver abscess.

Clinical Considerations

• Serology should be interpreted alongside clinical presentation and imaging findings, as antibodies may persist after treatment.
• In patients with diagnostic uncertainty, a percutaneous aspiration may be warranted, as mentioned in the study by 1.
• It's essential to consider the patient's travel history and exposure to endemic areas when interpreting serological results.

From the Research

Serological Diagnoses of Amoebic Liver Abscess

The best serological diagnoses of amoebic liver abscess can be determined by evaluating the sensitivity, specificity, and predictive values of various tests.

• ELISA (Enzyme-Linked Immunosorbent Assay) is a commonly used test for the serodiagnosis of amoebic liver abscess.
• The sensitivity and specificity of ELISA for the diagnosis of amoebic liver abscess have been reported to be high, with values ranging from 95.7% to 100% and 96% to 100%, respectively 2, 3, 4.
• Enzyme immunoassay is another test that has been used for the diagnosis of amoebic liver abscess, but its sensitivity and specificity are not as well established as those of ELISA.
• A study comparing ELISA and counterimmunoelectrophoresis (CIE) found that ELISA was more sensitive than CIE for the diagnosis of amoebic liver abscess, with a sensitivity of 100% versus 66% 4.
• Another study found that ELISA made with antigens preserved without using enzymatic inhibitors had valuable serodiagnostic value to diagnose acute amoebic liver abscess, even in populations living in endemic zones of amoebiasis carrying antibodies against amoebas 3.
• However, a negative serologic test does not rule out the diagnosis of invasive amoebiasis 3, 5.
• The TechLab E. histolytica II ELISA was found not to be useful for serological diagnosis of ALA at Hospital Universiti Sains Malaysia (HUSM), Kelantan, Malaysia, due to its low sensitivity and poor agreement with IHA results 6.

Comparison of Diagnostic Tests

• The diagnostic parameters of ELISA, including sensitivity, specificity, positive predictive value, and negative predictive value, are generally higher than those of other tests, such as IHA and CIE 2, 3, 4.
• ELISA has been found to be more sensitive and specific than IHA for the diagnosis of amoebic liver abscess, especially in endemic areas 3.
• The use of antigens preserved without enzymatic inhibitors in ELISA has been shown to improve the diagnostic parameters of the test 3.
• PCR (polymerase chain reaction) may be used as an alternative test to anti-amoebic antibody in the diagnosis of ALA, especially in patients who have received prior anti-amoebic treatment 5.