As VP4 of genotype P[8] is a component of current RV vaccines, our finding that Lewis-negative children are resistant to P[8] strains provides a plausible explanation for the reduced vaccine efficacy in populations with a high percentage of Lewis-negative individuals, such as in Africa. Furthermore, our findings provide a plausible explanation as to why P[6] RV strains are more common in Africa.

This study demonstrates rotavirus as the main etiological agent in pediatric diarrhea in Burkina Faso, and further shows the great severity of rotavirus-induced diarrhea in undernourished children in Burkina Faso.

Norovirus (NoV) constitutes the second most common viral pathogen causing pediatric diarrhea after rotavirus. In Africa, diarrhea is a major health problem in children, and yet few studies have been performed regarding NoV. The association of histo-blood group antigens (HBGA) and susceptibility to NoV infection is well established in Caucasian populations with non-secretors being resistant to many common NoV strains. No study regarding HBGA and NoV susceptibility has yet been performed in Africa. We collected 309 stool and 208 saliva samples from diarrheal children in Ouagadougou, Burkina Faso; May 2009 to March 2010. NoV was detected using real-time PCR, and genotyped by sequencing. Saliva samples were ABO, Lewis and secretor phenotyped using in house ELISA assays. NoV was detected in 12% (n = 37) of the samples. The genotype diversity was unusually large; overall the 37 positive samples belonged to 14 genotypes. Only children <2 years of age were NoV positive and the GII.4 NoVs were more frequent in the late dry season (Jan-May). NoV infections were observed less in children with the secretor-negative phenotype or blood group A (OR 0.18; p = 0.012 and OR 0.31; p = 0.054; respectively), with two non-secretors infected with genotypes GII.7 and GII.4 respectively. Lewis-negative (Lea−b−) children, representing 32% of the study population, were susceptible to GII, but were not infected with any NoV GI. GII.4 strains preferentially infected children with blood group B whereas secretor-positive children with blood group O were infected with the largest variety of genotypes. This is the first study identifying host genetic factors associated with susceptibility to NoV in an African population, and suggests that while the non-secretor phenotype provides protection; the Lewis b antigen is not necessary for GII infection.

High incidence highlights the need for long-term surveillance of rotavirus strains.

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Background A significant fraction of cases of diarrhea, a leading cause of childhood mortality worldwide, remain unexplained. Objectives To identify viruses in unexplained cases of diarrhea using an unbiased metagenomics approach. Study design Viral nucleic acids were enriched from the feces from 48 cases of unexplained diarrhea from Burkina Faso, sequenced, and compared against all known viral genomes. Results The full genome of a highly divergent astrovirus was sequenced in a sample co-infected with parechovirus 1. RT-PCR identified a single astrovirus infection in these 48 patients indicating a low prevalence. Human astrovirus-BF34 was most closely related to mamastrovirus species 8 and 9 also found in human with which it shared 62%, 74%, and 57% amino acid identities over its protease, RNA dependent RNA polymerase and capsid proteins, respectively. Conclusions Burkina Faso astrovirus is proposed as prototype for a novel species in the genus Mamastrovirus, here tentatively called Mamastrovirus 20, representing the fifth human astrovirus species.

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