An ELISA test for the serological diagnosis of amoebic liver
abscess (ALA) was standardized and evaluated in sera from
three groups of patients: (1) three patients with diagnosis
confirmed by isolation of the parasite, (2) thirty seven
patients with diagnosis established by clinical findings and
ultrasound studies and (3) seven patients whose diagnosis were
established by clinical findings and a positive double
immunodifusion test. Ninety one serum samples from healthy
subjects and 22 from patients with other liver or parasitic
diseases were also included in the study.
The optimum concentration of Entamoeba histolytica antigen
was 1.25 ug/ml and optimum dilutions of serum and anti-human
IgG -alkaline phosphatase conjugate were 1:400 and 1:4000
respectively. The cut-off point of the ELISA test in this
study was an absorbance value of 0.34. The test parameters
were: sensitivity = 95.7%, specificity = 100%, positive
predictive value = 100% and negative predictive value = 98.2%.
The ELISA test was found to be of great use as a
diagnostic tool for the establishment of amoebic etiology in
patients with clinical supposition of ALA. The test could also
be used for seroepidemiological surveys of the prevalence of
invasive amoebiasis in a given population, since it allows the
processing of a greater number of samples at a lower cost than
other serological tests.