Diagnosis of invasive amebiasis by enzyme-linked immunosorbent assay of saliva to detect amebic lectin antigen and anti-lectin immunoglobulin G antibodies

Saliva from subjects with amebic liver abscess (ALA), acute amebic colitis, asymptomatic infection with Entamoeba histolytica or Entamoeba dispar, and uninfected controls was tested by enzyme-linked Immunosorbent assay (ELISA ) for the presence off. histolytica galactose-inhibitable lectin antigen an d salivary immunoglobulin (IgG) antibodies to a recombinant cysteine-rich l ectin-derived protein (LC3). Salivary lectin antigen was found in 65.8% of subjects with acute colitis, compared to 22.2% of those convalescent from A LA, 10.0% with asymptomatic E. histolytica infection, 9.8% with E, dispar i nfection, and 2.6% of controls (subjects from the United States and study p atients with nonamebic diarrhea) (P < 0.001 for each compared to values for subjects with colitis). Salivary anti-LC3 IgG antibodies were found in 92% of ALA patients regardless of duration of illness and in 83.3% of colitis patients who were symptomatic for at least 7 days (P < 0.001 compared to ot her study groups). Serum anti-LC3 IgG antibodies were detected in 56.3% of subjects with acute colitis, 100% of subjects with ALA or prolonged colitis , 45% of subjects with asymptomatic E. histolytica infection, 32.3% of subj ects with E. dispar infection, and 23.4% of diarrhea controls. In compariso n to ELISA for serum anti-LC3 IgG antibodies, the salivary lectin antigen a ssay is a more sensitive and specific test for acute amebic colitis, Detect ion of salivary anti-LC3 IgG antibodies by ELISA is an effective means for the diagnosis of ALA and prolonged cases of amebic colitis.