Background: Acute diarrhea is a leading cause of morbidity and mortality among children under five worldwide. As no published data is available on the occurrence of this infection in the Republic of Congo, this study aimed at (1) determining the prevalence and (2) characterizing genotypes of norovirus strains in Brazzaville. Methods: From June 2012 to June 2013, stool samples were collected from hospitalized young children with acute gastroenteritis. A total of 545 samples were tested for GI and GII norovirus infections using nested duplex reverse-transcription-polymerase chain reaction and sequencing. Results: The GI and GII norovirus infection were detected in 148 samples. Males (28%) were not significantly more infected than females (25%). Norovirus infection was found exclusively in children aged under 24 months with a higher prevalence (P = 0,048) in the age group of 7-12 months, and throughout the year with a peak in August and September. Genetic diversity of norovirus strains revealed that GII was the most prevalent (87%). No risk factor was significantly associated with norovirus infection. Conclusion: This study showed that noroviruses are important agents responsible for acute diarrhea in Congolese children and highlights the importance of continued surveillance.

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objective To evaluate the clinical severity of diarrhoea associated to viral co-infection in children with acute gastroenteritis.methods About 461 children under five years hospitalised with acute diarrhoea (266 males and 187 females) were enrolled in the study. Using stool samples, rotavirus and adenovirus infections were investigated by ELISA, and norovirus infections by nested duplex RT-PCR. We assessed social, demographic, clinical and behavioural conditions that might influence the occurrence of rotavirus, adenovirus and norovirus infections.results Mono-viral infection was detected in 49% and mixed viral infection in 12% of patients. The prevalence of mixed infection was neither dependent on age nor sex. Three samples were infected with all three viruses. A significant association was found between fever (axillary temperature> 37.5°C) and rotavirus-norovirus dual infection (aOR (CI 95%) = 2.1 (1.14-3.84), P = 0.016; aOR (CI 95%) = 0.37 (0.19-0.73), P = 0.004). Mixed infection was the most common during the dry season from June to October (71.4% versus 54.7%, P = 0.023).conclusion Co-infection with both rotavirus and norovirus is common in under-five hospitalised children but does not contribute to the severity of the disease.