Human norovirus in rural communities of Vhembe District, Limpopo Province - South Africa

Abstract

BACKGROUND: Human norovirus (NoV) is the etiological agent associated with acute gastroenteritis (AGE) in both children and adults worldwide. Children of <5 years of age, the elderly and individuals suffering from chronic diseases are potentially at high risk of NoV-associated illness. High morbidity and mortality rate associated with NoV have been reported worldwide. In children under the age of 5 years about 1.8 million death cases have been reported in developing countries alone. Despite the fact that the virus is affecting people of all age groups, there is lack of data to elucidate the importance and the role of NoV in children of the age above 5 years and adults. OBJECTIVE: To characterize human norovirus in patients with diarrhoea in rural communities of Vhembe district, Limpopo province. MATERIALS AND METHODS : From August 2017 to October 2018, outpatient between 5 and 68 years of age from rural communities of Vhembe district, Limpopo province were recruited for this study. A total of n=80 stool samples were collected from patients with diarrhoea and were kept at 4˚C throughout the transportation to the laboratory and refrigerated at - 20˚C prior to RNA extraction. Stool samples were tested for norovirus using the RIDA©GENE NOROVIRUS I & II real-time RT-PCR. The RNA extracts tested positive for norovirus were subjected to RT-PCR amplification. The RT-PCR products of the amplified fragments were sequenced, and phylogenetic trees were constructed by the neighbor-joining method using MEGA 7 software. RESULTS: NoV was detected in 13(16%) out of 80 stool samples collected, of which 6 (46%) strains belonged to norovirus GII and 7 (54%) strains to norovirus GI. A total of 5 genotypes were detected (GII.Pg, GII.1, GII.2, GII.4 Sydney 2012). The phylogenetic analysis revealed circulation of NoV genotypes with considerable diversity. CONCLUSION: This study illustrates NoV prevalence and substantial genetic diversity in patients above 5 years of age living in rural communities of Vhembe district, Limpopo province. Continued systematic surveillance to evaluate norovirus association with diarrhoea is needed to have a full picture on the epidemiology and disease burden in people of all the age groups.