Background: Giardia duodenalis is one of the most common human intestinal protozoan
parasites worldwide and is endemic throughout the world with a vast range
of mammalian hosts. The present study aimed to identify the prevalence of G. duodenalis
isolates and determine the most common of its assemblages in the patients
referring to health centers and hospitals in Fars province, Iran that will be subjected
to further molecular investigation.
Methods: We collected 1000 human fecal samples from health centers and hospitals
in Shiraz, Iran in a one year period from September 2009 to August 2010. Microscopic
examination for the presence of G. duodenalis cysts and trophozoites was
performed by direct wet mount before and after the concentration techniques. Extraction
of DNA was performed by Phenol-Chloroform-Isoamylalcohol (PCI). G.
duodenalis-positive specimens were analyzed by PCR. A fragment of the SSU-rDNA
(292 bp) gene was amplified by PCR using the forward primer RH11 and the reverse
primer RH4. Genotyping was performed using sequence analysis of G. duodenalis
glutamate dehydrogenase gene using primers GDHeF, GDHiF, and GDHiR.
Results: The prevalence of Giardia infection was 10.7% (107/1000) examined
based on microscopic examination. PCR identified 80% (40/50) of the samples as
positive for G. duodenalis based on SSU-rDNA amplification on sucrose gradient
samples. Besides, genotyping results indicated 32 isolates (80%) as assemblage AII
and 8 isolates (20%) as assemblage BIII and BIV based on the DNA sequence
analysis of the glutamate dehydrogenase locus of G. duodenalis.
Conclusion: The findings of this study emphasize that Iran (Fars Province) is a
favorable area for giardiasis with an anthroponotic infection route