Background: Despite the introduction of rotavirus vaccines, gastroenteritis remains a major cause of paediatric morbidity and mortality in the Republic of Congo. This study investigated the prevalence and genetic diversity of non-rotavirus enteric viruses including Norovirus (NoV), Adenovirus (AdV), and Astrovirus (AstV) ten years after the introduction of the rotavirus vaccine in 2014. Methods: A cross-sectional study between 2022 and 2023 in 227 children (≤5 years) hospitalized with acute gastroenteritis in Brazzaville was conducted. Stool samples were analysed by Multiplex RT-PCR to detect RVA, NoV, AdV, and AstV. Positive NoV and AstV samples underwent genotyping by PCR and sequencing. Results: The incidence of gastroenteritis peaked during the dry season, with the highest burden observed among children aged 6-24 months. Overall, 170/227 (75%) children tested positive for at least one virus: RVA was detected in n=131/227 children (58%), followed by NoV (n=77/227, 34%), AstV (n=24/227, 11%), and AdV (n=16/227, 7%), while 57 children (25%) tested negative for all four viruses. Co-infections were observed in n=46/227 children (20%), most commonly RVA-NoV. NoV genotyping revealed a predominance of GII.P31 (82%), and AdV was mainly type 41 (67%). Notably, from November 2022, gastroenteritis of unknown aetiology peaked, coinciding with a decline in the four targeted viruses. Conclusion: NoV, AstV, and AdV continue to contribute to the gastroenteritis burden in Congolese children. The high circulation of NoV and the seasonal surge of unexplained cases highlight the need for broadened molecular surveillance, incorporation of bacterial diagnostics, and consideration of future NoV vaccine strategies.

Statements of the problem: Dengue pathogenesis is complex and not fully understood. The virus may evade the immune system through mechanisms like the increased expression and/or secretion of immune inhibitory molecules. This study examines the association of the soluble human leukocyte antigen G (sHLA-G) with dengue in hospitalized patients. Method of study: A total of 238 dengue patients and 118 healthy controls were recruited. Dengue-infected patients were confirmed by real-time RT-PCR and clinically categorized into different severity groups. Laboratory parameters were assessed on admission. Plasma sHLA-G levels were measured by a commercial ELISA. Results: sHLA-G levels were significantly higher in dengue patients (median [range]: 42.7 [7.10 - 1300] U/mL) compared to healthy controls (median [range]: 11.1 [4.7 - 620] U/mL) (p<0.001). After adjusting for age, sex and disease severity, a significant association between sHLA-G plasma levels (log-transformed) and the days of illness was observed (β=0.1, p=0.033). Cases requiring strict medical monitoring presented significantly higher sHLA-G level (median [range]: 51.0 [7.17 - 525] U/mL), compared to cases without warning signs (median [range]: 38.0 [7.10 - 1300] U/mL) (p=0.011). While liver enzymes positively correlated with sHLA-G levels in all patients, total lymphocyte counts inversely correlated with sHLA-G levels in severe cases (r=-0.78, p-value=0.002). Conclusions: sHLA-G levels are associated with dengue warning signs and severe cases, suggesting a role in disease pathogenesis. Thus, this soluble protein might be a valuable marker to improve the accuracy of identifying severe cases and support clinical monitoring.