Determining the Prevalence of Norovirus Infection in Diarrheal Patients and Evaluation of Different Diagnostic Methods

Norovirus is one of the viruses that cause gastroenteritis in humans, characterized by symptoms of vomiting and diarrhea. The prevalence of norovirus, known as the leading cause of epidemic gastroenteritis, is remarkable in sporadic cases. Easy-to-apply diagnostic methods based on antigen detection such as enzyme immunoassay (EIA) and immunochromatography (ICG) used to diagnose norovirus infections generally have high specificity rates but lower sensitivity rates that can change according to the conditions. In this study it was aimed to determine the prevalence of norovirus and other gastroenteritis causative viruses in diarrheal patients and determine the sensitivity and specificity rates of EIA and ICG methods in sporadic cases by the chosen gold standard molecular reference method real-time reverse transcriptase polymerase chain reaction (rRT-PCR). In this study, 184 stool samples that met the study criteria and sent to İstanbul University İstanbul Faculty of Medicine Medical Microbiology Laboratory for routine bacteriological culture between January-July 2018 were included. All samples were evaluated with diagnostic kits BD MAX Enteric Viral Panel (Becton Dickinson, Canada) for rRT-PCR, RIDASCREEN Norovirus 3rd Generation (C1401) (R-Biopharm, Germany) for EIA, RIDAQUICK Norovirus Test (N1402) (R-Biopharm, Germany) for ICG, according to the manufacturer instructions. In terms of the presence of norovirus in 184 stool samples, 7 (3.8%) positive results were obtained by EIA method, 8 (4.3%) by ICG method, and 14 (7.6%) by rRT-PCR method. By accepting the rRT-PCR as a reference method, the sensitivity and specificity of the EIA method were determined as 50% and 100% and of the ICG method as 57% and 100%, respectively. The numbers and percentages of positivity for rotavirus, sapovirus, astrovirus and adenovirus, including coinfections were 30 (16.3%), 5 (2.7%), 2 (1%), 1 (0.5%), respectively. In this study, it was determined that norovirus, alone or together with other viral agents is frequently detected in patients with diarrhea and there was no difference in the frequency between age groups and genders. This causative agent which is not routinely investigated in our country should be considered when evaluating patients with diarrhea and/or vomiting. It seems that EIA and ICG methods are easy to apply, have high specificity but have limited sensitivity in sporadic cases in the diagnosis of norovirus. It is thought that the detection of the true frequency o