Comparative study between immunohistochemical grading and giardia genotyping among symptomatic and asymptomatic humans.

In the last years, multiple studies indicated the potential effectiveness of the polymerase chain reaction (PCR) for detection of Giardia in pathological specimens. By using the difference at the triose phosphate isomerase (tpi) gene locus, we investigated the genotype groups of Giardia lamblia isolated directly from fecal specimens collected from humans living in Dakahlia Governorate, Egypt. Immunohistochemical staining for detection of Giardia local antigenic and cellular immune-determinants focusing on CD4 and CD8 T-lymphocytes was also applied. The sensitivity of the ABC (avidine-biotin-peroxidase complex) immunoperoxidase technique for detection of the antigen was 97.3% and the specificity was 100%. Our study clearly demonstrated a highly significant difference between patients and controls as regards the grade of CD4 and CD8 lymphocyte infiltration (p < 0.001 for each correlation) but no significant difference was found between Giardia symptomatic and asymptomatic patients. Using the PCR technique, 89.3% sensitivity, 100% specificity and diagnostic accuracy of 92% were reached. Nevertheless, there was statistically insignificant difference between symptomatic and asymptomatic groups regarding the prevalence of different Giardia genotypes and the prevalence of CD4 and CD8 lymphocyte infiltration grading in different Giardia genotypes.