Abstract
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.
Highlights
Norovirus (NoV) is the most common cause of acute gastroenteritis worldwide, and it is estimated to cause 200, 000 deaths in children world-wide, mainly in developing countries [1]
NoV infections were associated with fever (49%), vomiting (49%), and dehydration (62.4%) (Table 1)
Nineteen (51%) of the NoV-positive samples were infected with other enteropathogens screened for in previous studies
Summary
Norovirus (NoV) is the most common cause of acute gastroenteritis worldwide, and it is estimated to cause 200, 000 deaths in children world-wide, mainly in developing countries [1]. In sub-Saharan Africa, molecular epidemiology studies of NoV have been performed in countries such as South Africa, Cameroon, Botswana, Malawi and Ghana [11,12,13,14,15]. Many studies have been performed in Caucasian populations, the genetic polymorphisms that determines presence of HBGAs, secretor and Lewis phenotypes, in African populations are different [26] and as of yet, no study has attempted to investigate how this could influence susceptibility to NoV in Africa. We found that NoV-infection was as common in Lewis-negative children representing 32% of the investigated, as in Lewis b positive children (54% of investigated) demonstrating that the Lewis b antigen is not required for symptomatic NoV infection for many genotypes
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