Abstract
Aim:The aim of the present study was to detect the prevalence of norovirus and genotypes determination by real-time PCR among children below 18 years as an etiology of acute gastroenteritis and to compare rapid detection of norovirus by Enzyme-Linked Immunoassay (ELISA) to virus detection by real-time PCR.Methods:The research was a cross-sectional study conducted on children below 18 years complaining of community-acquired acute gastroenteritis. A stool sample was subjected to direct-antigen detection by ELISA for norovirus and molecular study by real-time polymerase chain reaction.Results:The study included 200 children with acute gastroenteritis with a mean age of 6.7±3.8 years. Norovirus antigen was detected by EIA in 34.5% and by real-time PCR in 30.5% of studied children with genotype GII, the predominant detected genotype (80.97%). Both real-time PCR and antigen detection of norovirus were positive in 43 (70.5%) of the children and negative in 113(81.3%) of the studied children. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for antigen detection by ELISA were 70.5%, 81.3%, 62.3%, 86.3% and 78%, respectively. Comparison between patients positive for norovirus and those negative for norovirus by real-time PCR revealed non-significant difference as regards age, sex, the season of occurrence and residence.Conclusion:The present study highlights that norovirus prevalence is common among pediatric patients with gastroenteritis above 5 years with GII genotype as the prevalent genotype. There was a significant correlation between positive and negative results of antigen detection of norovirus by ELISA and detection of RNA of norovirus by real-time PCR in stool samples. However, the screening for norovirus by ELISA has limited sensitivity and needs to be associated with a molecular method for accurate diagnosis of sporadic cases of gastroenteritis.
Highlights
Acute diarrhea is a common cause of morbidity in children worldwide
The accuracy of Enzyme-Linked Immunoassay (ELISA) depends upon factors such as the number of samples used for each patient and the time of the sample obtaining after infection
The research was a cross-sectional study conducted on children below 18 years complaining of community-acquired acute gastroenteritis recruited from Mansoura University Children Hospital outpatient clinics, Egypt from January 2018 till May 2019
Summary
Acute diarrhea is a common cause of morbidity in children worldwide. Rotavirus, as an etiology of acute diarrhea, has been decreased after the implementation of vaccine and norovirus has become the most prevalent viral etiology of acute gastroenteritis [1].Norovirus is a non-enveloped RNA virus associated with acute gastroenteritis transmitted by fecal-oral route in all age Diagnostic methods for norovirus include non-culture methods as norovirus cannot be cultivated in cell culture [8]. The diagnostic methods include antigen identification in stool samples by Enzyme-Linked Immunoassay (ELISA). The Open Microbiology Journal, 2019, Volume 13 325 linked immunoassay detects norovirus antigen by the use of either monoclonal or polyclonal antibodies with sensitivity less than 70% and high specificity above 90% as reported by previous studies [8, 9]. The specific diagnosis of norovirus has been facilitated in recent years by the use of reverse transcription-polymerase chain reaction PCR (RT-PCR) [10]. This method coupled with nucleotide sequencing techniques is able to gather valuable information on the norovirus and provide epidemiological information of norovirus infections in the community. The RT-PCR primers that target the viral RdRp gene in Open Reading Frame 1 (ORF1) or capsid gene in ORF2 have been designed to detect and genotype various norovirus strains [11]
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