Журнал инфекционных заболеваний и терапии

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Prevalence and Genetic Diversity of Human Norovirus Diarrhoea Among Children With Gastroenteritis in Africa: (Systematic Review and Meta-Analysis)

Sheriffo Jagne* Jarde Alexander, Nuredin Ibrahim Mohammed, Osbourne Quaye, Kwambana Adams Brenda, George Armah, Martin Antonio

Background
Africa has the highest burden of norovirus associated gastroenteritis. This review aims to estimate norovirus prevalence and the distribution of circulating genogroups, genotypes and Gll.4 variants among children under 5 years with acute gastroenteritis in Africa. 
Methods
A literature search was conducted using PubMed, biomed search.com, Ovid search, Cochrane and Popline. The
inclusion criteria were study duration of at least 2months and diagnosis by RT-PCR . The data retrieved from articles
included in this review included prevalence, sample size, norovirus positives, genotypes and genogroups. Data were
computed for meta-analysis to estimate the prevalence and genetic diversity of norovirus among Africans children
with acute gastroenteritis.
Results
The literature search containing Norovirus and Africa using the above stated databases produced 170 published
articles. Out of the searched
Human norovirus is associated with 18% (95% Cl: 17-20%) of diarrhoeal diseases and is one of the major causes
of acute gastroenteritis in children worldwide. Noroviruses account for about one fifth of acute gastroenteritis cases
in the world . Norovirus is an enteric virus known to play an important role in acute gastroenteritis in children.
Noroviruses have been associated with the hospitalisation of children with acute gastroenteritis with the highest
burden in children under five years of age.
Noroviruses are small non-enveloped single stranded RNA viruses in the calciviridae family. It has a genome size
of about 7.5kb, organised into three open reading frames (ORF) ORF1 to ORF3. The genome is highly liable to
mutation and recombination which causes emergence of new strains and high genetic diversity in noroviruses .
Noroviruses have different strains whose genome can easily recombine that could lead to diverse mixed infections. .
Noroviruses are classified into six genogroups (GI-GVI) and genogroups GI, GII and GIV are known to infect
humans. Among the genogroups that are known to infect humans, GII is the most predominant genogroup and also
causes more than 70 articles, 33 articles from 15 countries met the inclusion criteria. Studies conducted in countries
that did not meet the inclusion criteria were included in the discussion. The majority of the studies included in this
review mainly focused on children less than 5 years of age hospitalized with acute gastroenteritis. Genotypic data
from 15 countries revealed 31 genotypes and 13 Gll.4 variants with Sydney 2012 as the most common circulating
variant across the continent. Norovirus genogroup 2 (Gll) and norovirus genotype Gll.4 had remained the most
dominant genogroup and genotype detected in the majority of studies conducted.

Conclusion

Norovirus genogroup 2 (Gll), genotype Gll.4 and Sydney 2012 Gll.4 variant are commonly associated with
childhood diarrhea in Africa however, only few studies were conducted within the region with limited data. The
analysis revealed norovirus genetic diversity among genogroups, genotypes and variants. Norovirus surveillance
should be implemented in Africa to assess the prevalence and genetic diversity of human noroviruses in children
with acute gastroenteritis.