Genetic variation of Giardia lamblia isolates from food-handlers in Kashan, Central Iran

<p><strong><em>Background:</em></strong> Based on genotyping study of human isolates of <em>Giardia lamblia</em>; humans are mainly infected by two assemblages A and B. The present study was carried out to determine the sub-assemblages of <em>G. lamblia</em> isolated from food handlers referred to Kashan health centers, central Iran, 2015.</p><p><strong><em>Methods:</em></strong> In this cross-sectional<strong> </strong>study,<strong> </strong>3653 stool samples collected from food-handlers that annually refer to health center for getting a health certification and examined microscopically for <em>G. lamblia</em> cyst. Totally, 44 isolates were selected from 47 <em>Giardia</em> positive samples. Cysts were partially purified by the sucrose density gradient method. After freeze-thaw cycles, genomic DNA was extracted using QIAamp Stool Mini kit. A single step PCR-RFLP method was used to amplify a 458bp fragment at the glutamate dehydrogenase <em>(gdh</em>) locus, restriction enzymes <em>BspLI </em>and <em>RsaI</em> were used for distinguish between genotypes A and B and their subgroups.</p><p><strong><em>Results:</em></strong> Of 44 isolates, 24(54.5%) were sub-assemblage AII, 9(20.5%) group B including 7(15.9%) BIII and 2(4.6%) BIV sub-assemblage and 11(25%) isolates showed a mixed pattern of AII and B. Sub-assemblage AI was not detected in this study.</p><strong><em>Conclusion:</em></strong> The higher rate of sub-assemblage AII demonstrated an anthroponotic origin of the infection so infected food-handlers could directly transmit this protozoan to consumers via contaminated food and water. For finding of pattern of transmission and distribution of <em>Giardia</em> assemblages and sub-assemblage, more studies in human and animal population in different regions are necessary