The serodiagnosis of amoebiasis by enzyme-linked immunosorbent assay

We attempt to detect antibodies against Entamoeba histolytica in sera obtained from both healthy individuals and hospitalized patients by an enzyme-linked immunosorbent assay (ELISA). The limiting value for ELISA-positive was established on the basis of serologic results of 1869 healthy persons living in a non-endemic area (Japan)> The ELISA then was applied to 61 patients in 5 hospitals in Myanmar who were suspected of having amoebiasis. The ELISA results were compared with those of stool examinations, and evaluated for sensitivity. Using the llimiting value for the ELISA, there was an 83 Percent agreement of positivity between the ELISA tests and microscopic examinations. Specific anti-E-histolytica IgM was observed in the sera of 44 patients; IgG in all of the 61 patients. Since high titers of specific IgM were not observed in both stool-positive and stool-negative patients, we judged that patients with early stages of amoebic infections were not included in this population. In our ELISA, the sera of the patients did not exhibit crosss-reactions betweeen antigens prepared from the HK-9 strain of E. histolytica and antigens prepared from Trichomonas vaginalis and Giardia lamblia. On the basis of these results, we suggest that it is necessary to do two or more different examinations in order to make a definite diagnosis of amoebic infection.