Diagnosis of multiple enteric protozoan infections by enzyme-linked immunosorbent assay in the Guatemalan highlands.

We tested a prototype stool enzyme-linked immunosorbent assay (ELISA) (TRI-COMBO) that is simultaneously diagnostic for Giardia lamblia, Cryptosporidium parvum, and Entamoeba histolytica in a rural pediatric clinic in Guatemala. We compared its results to those of three individual ELISAs for these parasites, assessed the prevalence of these parasites, and compared our findings to those found by stool microscopy. We tested 620 non-diarrheal stools. The TRI-COMBO diagnosed 57 positive samples and 52 (91%) had a correlating positive result in an individual assay, giving a kappa coefficient of 0.90. Giardia spp., E. histolytica, and Cryptosporidium spp. were detected in 52 (8.4%), 2 (0.3%), and 3 (0.5%) samples, respectively. Twenty-three (40%) samples positive by ELISA for Giardia spp. were identified by microscopy. This study is the first to test the TRI-COMBO in this setting and, to our knowledge, represents the first assessment of these parasites in Guatemala by stool ELISA.