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. 2017 Oct;141:35-41.
doi: 10.1016/j.mimet.2017.07.004. Epub 2017 Jul 14.

Stool Antigen Immunodetection for Diagnosis of Giardia Duodenalis Infection in Human Subjects With HIV and Cancer

Free PMC article

Stool Antigen Immunodetection for Diagnosis of Giardia Duodenalis Infection in Human Subjects With HIV and Cancer

Maryam Nooshadokht et al. J Microbiol Methods. .
Free PMC article


Human infection with the protozoan parasite Giardia duodenalis is one the most common parasitic diseases worldwide. Higher incidence rates of giardiasis have been reported from human subjects with multiple debilitating chronic conditions, including hypogammaglobulinemia and common variable immunodeficiency (CVID). In the current study, stool specimens were collected from 199 individuals diagnosed with HIV or cancer and immunocompetent subjects. The sensitivity of microscopy-based detection on fresh stool preparations, trichrome staining and stool antigen immunodetection for the diagnosis of G. duodenalis were 36%, 45.5% and 100%, respectively when compared with a highly sensitive stool-based PCR method as the gold standard. Further multilocus molecular analyses using glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) loci demonstrated that the AI genotype of G. duodenalis was the most prevalent, followed by the AII genotype and mixed (AI+B) infections. We concluded that stool antigen immunodetection-based immunoassays and stool-based PCR amplification had comparable sensitivity and specificity for the diagnosis of G. duodenalis infections in these populations. Stool antigen detection-based diagnostic modalities are rapid and accurate and may offer alternatives to conventional microscopy and PCR-based diagnostic methods for the diagnosis of G. duodenalis in human subjects living with HIV or cancer.

Keywords: Assemblage; Cancer; Genotype; Giardia duodenalis; Giardiasis; HIV.

Conflict of interest statement

Conflict of Interest: The authors declare that they have no conflict of interest.


CD4+ T cell absolute counts in HIV-positive human subjects with or without concomitant enteric parasitic infections. Peripheral CD4+ T cell counts were determined using a Partec CD4 Easy Count kit. *p < 0.05 (a two-tailed Mann-Whitney U test). Scatter plots represent Mean ± SEM.
Gel electrophoresis of the semi-nested PCR amplification of a 432-bp fragment of the gdh locus of G. duodenalis. M, DNA ladder (Thermo Scientific); lane 1, positive control; lanes 2–5 patient’s clinical samples; lane 6, negative control (no DNA) (A). The restriction enzyme digestion of the PCR product targeting the G. duodenalis gdh locus using BspLI (NlaIV). Lanes 1 and 2, AI genotype; lane 3, AI+B; lane 4, undigested PCR product; M, DNA ladder (B). Gel electrophoresis of the semi-nested PCR amplification of a 476-bp fragment of the tpi gene of G. duodenalis (C). M, DNA ladder; lane 1, no DNA; lanes 2, 3 undigested PCR products (assemblage A); lanes 4, 5 AII genotypes; lanes 6, 7 AI genotypes. The characteristic band of 15-bp is not visible. Sizes in base pairs are represented by the numbers on the left.

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