Human Noroviruses (NoVs) are the leading cause of gastroenteritis in all age groups worldwide. NoV is a small, non-enveloped virus that belongs to the family Calciviridae and is characterized by high infectivity and stability. NoVs are genetically and antigenically diverse and have been divided into seven genogroups (GI-GVII) on the basis of nucleotide and amino acid sequences and each genogroup can be further divided into genotypes. The aim of this study was to determine the presence of NoVs Genogroup II in samples from Tehran and Alborz provinces residents with acute gastroenteritis symptoms.

A molecular epidemiological study of NoVs prevalence was performed in two provinces of Iran (Tehran and Alborz) from November 2017 to June 2018. A total of 120 stool specimens were collected from hospitalized patients with acute gastroenteritis and stored at -70oc until use. Viral RNA was extracted and reverse transcription Nested-PCR was employed to amplify and detect NoV genome. The N-terminal/Core region of NoV genome was amplified, then the nucleotide sequences were determined and phylogenetic analysis was performed.

The study population comprised of 54 males (45%) and 66 females (55%) with the age range from 1 month to 68 years. Main clinical symptoms were diarrhea, nausea, vomiting, abdominal pain and malaise. Totally, 6 of 120 samples (5%) were positive for GII NoVs infection. No difference in GII NoVs infection frequency was observed between male or female groups (4.8% vs 5.9% respectively, P value=0.801).

The findings indicate that GII NoVs is one of the most important etiologies of acute gastroenteritis among patients from Tehran and Alborz provinces. Although the prevalence of GII NoVs is lower than other developing countries, promoting public health education and preparation of health care setting for controlling the Norovirus sporadic cases and outbreaks are strongly recommended.