Molecular detection of glutamate dehydrogenase gene of Giardia lamblia isolated from food handlers in Erbil city

Background and objective: Giardia lamblia is the intestinal flagellated protozoan parasite that infects vertebrates, including humans. Giardiasis is the major diarrheal disease found worldwide. It can be symptomatic or may be an asymptomatic carrier that led to chronic disease. This study aimed to determine the proportion of giardiasis among food handlers and evaluate the correlation between two laboratory methods for identifying the Giardia lamblia. Methods: A total of 308 stool samples were collected from food handlers that annually attend the central laboratory in Erbil City. Wetmount microscopic examination was performed for the diagnosis of cysts and trophozoites of the Giardia parasite. Molecular analysis done for positive samples, DNA extraction performed using the QIAamp Fast DNA Stool Mini Kit (Qiagen Company, Germany). Nested PCR analysis was done targeting the Glutamate dehydrogenase gene using two sets of primers for amplification of 734bp fragment. Gel electrophoresis was performed for visualizing the amplified DNA by Ultraviolet light. Results: The mean age of food handler participants was 29 years. Most (93.8%) of the food handlers were males, and the majority (98.6%) of the participants did not have any signs and symptoms. Four (7.4%) microscopy positive sample participants were highly educated. There was no association between educational level and positive rate by microscopy (P = 0.066). The majority of participants did not receive treatments, particularly most of the microscopic positive samples. The food handlers did not take any antiparasitic treatments 9 (3.4%) (P = 0.676). From 11 (3.6%) microscopically positive samples, 10 (90.9%) Giardia lamblia gdh gene 734 bp fragments were amplified by nested PCR. Conclusion: Amplification of 734bp of gdh gene by the nested PCR is the most specific and sensitive method for identifying Giardia lamblia. Food handlers were important people to care about sanitation and preparing food, particularly for avoiding diseases transmitted by food. Keywords: Giardiasis; Genetic characterization; gdh gene; Nested PCR.