Genotyping of G. duodenalis in the People Referred to Health Centers of Semnan City.

Giardia duodenalis (G. duodenalis), is one of the major causes of gastrointestinal disorders worldwide, infecting the small intestine of humans and animals. Based on the genetic characteristics of the parasite, eight genotypes (A to H) have been identified in clinical samples. The main purpose of the present study was to find the genetic diversity of Giardia in people referred to health centers in Semnan, Iran, using PCR. Totally, 300 stool samples were collected from people referred to health centers in Semnan. The stool samples were first examined using the microscopic method (direct method and Lugol staining), and the samples were checked with trichrome staining. After DNA extraction, the GDH gene of positive samples was amplified by the semi-nested PCR method. The genotype of positive samples was determined by the sequencing method. Out of 300 samples, only 20 (6.66%) samples were found to be positive in the microscopic examination of the stool. In the PCR test, only 13 (4.33%) of the samples were positive. According to the multiple alignment results, it was found that the isolates belonged to AII, BIII, and BIV genotypes. Most of which are related to people without clinical symptoms of diarrhea. Identification of AII, BIV, and BIII genotypes indicates the anthroponotic and anthropozoonotic transmission cycle of Giardia infection in Semnan.