Molecular Epidemiology of Norovirus Infections in Symptomatic and Asymptomatic Children from Bobo Dioulasso, Burkina Faso

Background: Noroviruses (NoV) are a leading cause of gastroenteritis worldwide. Few epidemiological data regarding the NoV strains circulating in African countries are available.

Objectives: To determine the prevalence of NoV in Bobo Dioulasso (Burkina Faso) in both symptomatic and asymptomatic gastroenteritis patients.

Study Design: Patients both with and without gastro-intestinal disorders were selected. Clinical and epidemiological data, as well as stool samples, were collected through March to April 2011. NoV molecular detection (genogrouping and genotyping) and viral load quantification were also performed for all samples.

Results: NoV were detected in 22.2% of the 418 collected stool samples (21.2% and 24.8% from the 293 symptomatic patients (SP) and the 125 asymptomatic patients (ASP) respectively). Genogroup (G) distribution was 7.5%, 10.2% and 3.4% for GI, GII and both GI/GII respectively among SP and 12.0%, 11.2% and 1.6% for GI, GII and both GI/GII, respectively, among ASP. Average viral load values were higher in SP than in ASP for GI (p = 0.03) but not for GII. Phylogenic analysis showed a high degree of genotype diversity in SP and ASP. One recombinant GII.7/GII.6 sequence was, to the best of our knowledge, detected for the first time.

Conclusions: This study enabled identification of the specific molecular epidemiology of NoV strains circulating in a representative country in Eastern Africa, and additionally showed that ASP could play an important "reservoir" role. A high strain diversity was detected with a surprisingly high proportion of NoV GI compared to the common genotypes usually reported in comparable epidemiological studies.