Pooled prevalence and genetic diversity of norovirus in Africa: a systematic review and meta-analysis

Abstract

Background Noroviruses are the leading cause of acute gastroenteritis in all age groups globally. The problem is magnified in developing countries including Africa. These viruses are highly prevalent with high genetic diversity and fast evolution rates. With this dynamicity, there are no recent review in the past five years in Africa. Therefore, this review and meta-analysis aimed to assess the prevalence and genetic diversity of noroviruses in Africa and tried to address the change in the prevalence and genetic diverisity the virus has been observed in Africa and in the world. Methods Twenty-one studies for the pooled prevalence, and 11 out of the 21 studies for genetic characterization of norovirus were included. Studies conducted since 2006, among symptomatic cases of all age groups in Africa, conducted with any study design, used molecular diagnostic methods and reported since 2015, were included and considered for the main meta-analysis. PubMed, Cochrane Library, and Google Scholar were searched to obtain the studies. The quality the studies was assessed using the JBI assessment tool. Data from studies reporting both asymptomatic and symptomatic cases, that did not meet the inclusion criteria were reviewed and included as discussion points. Data was entered to excel and imported to STATA 2011 to compute the prevalence and genetic diversity. Heterogeneity was checked using I2 test statistics followed by subgroup and sensitivity analysis. Publication bias was assessed using a funnel plot and eggers test that was followed by trim and fill analysis. Result The pooled prevalence of norovirus was 20.2% (95% CI: 15.91, 24.4). The highest (36.3%) prevalence was reported in Ghana. Genogroup II noroviruses were dominant and reported as 89.5% (95% CI: 87.8, 96). The highest and lowest prevalence of this genogroup were reported in Ethiopia (98.3%), and in Burkina Faso (72.4%), respectively. Diversified genotypes had been identified with an overall prevalence of GII. 4 NoV (50.8%) which was followed by GII.6, GII.17, GI.3 and GII.2 with a pooled prevalence of 7.7, 5.1, 4.6, and 4.2%, respectively. Conclusion The overall pooled prevalence of norovirus was high in Africa with the dominance of genogroup II and GII.4 genotype. This prevalence is comparable with some reviews done in the same time frame around the world. However, in Africa, an in increasing trained of pooled prevalence had been reported through time. Likewise, a variable distribution of non-GII.4 norovirus genotypes were reported as compared to those studies done in the world of the same time frame, and those previous reviews done in Africa. Therefore, continuous surveillance is required in Africa to support future interventions and vaccine programs.

Genetic Diversity of Norovirus in Children with Acute Gastroenteritis in Southwest Nigeria, 2015–2017

“…Similar to the RdRp genotypes, GII.4 was the dominant genotype based on the VP1 region. This is consistent with previous studies in Nigeria [ 21 , 23 ] and elsewhere globally [ 18 ]. This finding further corroborates the predominant widespread distribution of the GII.4 genotype over other GII genotypes.…”

“…Globally, viral gastroenteritis is still a public health issue, and NoV is significantly responsible for outbreaks and sporadic cases. The NoV detection rates of 5.1% and 2.3%, based on RdRp and VP1 regions, respectively, were lower than those reported in some earlier studies in Nigeria [ 21 , 22 , 23 , 24 , 25 ], and the pooled prevalence of 19.25% in Africa between 2015 and 2021 [ 18 ]. The observed discrepancy might be due to geographical location, sample size, study population, and varying diagnostic methods.…”

“…In line with this study, GII was reported as the only genogroup in Vietnam and Northern Italy [ 37 , 38 ]. Globally, GII is considered the predominant genogroup [ 18 ]. One of the RdRp- based genotypes identified in this study is GII.P31, which has been reported previously in Osun State, Nigeria [ 23 ], and elsewhere [ 13 , 39 ].…”

“…While extensive studies have been carried out on the prevalence and diversity of NoV in high- and upper-middle-income countries, only a few studies have been reported in middle- and low-income countries where high mortality rates exist [ 17 ]. The pooled prevalence of NoV in children below five years with AGE between 2015 and 2021 was 19.25% (95% CI: 14.4, 23.5) in Africa, with GII.4, GII.17 and GI.3 as predominant genotypes [ 18 ]. In Nigeria, existing studies reported NoV prevalence ranging from 3.6% to 37.3% [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ], with data on genotype distribution from solely two studies [ 21 , 23 ].…”

Norovirus Disease Among Children <5 Years in 3 Sub-Saharan African Countries: Findings From the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015–2018

“…We demonstrated that NVII is an important pathogen among infants seeking medical care with MSD in sub-Saharan Africa. Our findings corroborate and extend observations by others regarding the predominance of the NVII genogroup in Africa [ 25 ], and that circa 70% of pediatric norovirus diarrhea cases occur between age 6 and 23 months [ 26 ], commonly peaking between 6 and 11 months [ 11 ].…”