Epidemiology of norovirus infection in Nigeria: a systematic review and meta-analysis.

Human norovirus (HuNoV) is responsible for most cases of gastroenteritis worldwide, but information about the prevalence and diversity of HuNoV infections in lower-income settings is lacking. In order to provide more information about the burden and distribution of norovirus in Nigeria, we systematically reviewed original published research articles on the prevalence of HuNoV in Nigeria by accessing databases, including PubMed, Web of Science, ScienceDirect, Google Scholar, and African Journals Online (AJOL). The protocol for the review was registered on PROSPERO (registration number CRD42022308857). Thirteen relevant articles were included in the review, and 10 of them were used for meta-analysis. The pooled prevalence of HuNoV-associated gastroenteritis among children below 5 years of age in Nigeria, determined using the random-effects model, was 10.9% (95% CI, 6.7-16.7%). Among children below the age of 5 presenting with HuNoV infections, the highest prevalence was in children ≤2 years old (n = 127, 83%). The prevalence of HuNoV infections was seen to decrease with increasing age. In addition, HuNoV was detected in asymptomatic food handlers, bats, and seafoods. A total of 85 sequences of HuNoV isolates from Nigeria have been determined, and based on those sequences, the most prevalent norovirus genogroup was GII (84%). Genotypes GII.4 and GI.3 were the most frequently identified genotypes, with GII.4 constituting 46% of all of the HuNoVs identified in Nigeria. These results suggest a risk associated with cocirculation of emerging variants with known genotypes because of their recombination potential. Larger molecular epidemiological studies are still needed to fully understand the extent and pattern of circulation of HuNoVs in Nigeria.

Assessment of the aetiology of acute gastroenteritis outbreaks in infants reveals rotavirus, noroviruses and adenovirus prevalence and viral coinfections in Nsukka, Nigeria.

A better understanding of the aetiology of acute gastroenteritis (AGE) outbreaks in Southeast Nigeria would help safeguarding public health. This study screened stool samples collected from infants (children < 5 years of age) attending selected hospitals in Nsukka for human enteric viruses and evaluated the seasonality of AGE based on three-year records available at selected hospitals. A total of 120 stool samples (109 from diarrhoeal-patients and 11 from non-diarrhoeal patients, as control) collected during the AGE outbreaks of January - March 2019 and January-February 2020. The samples were analysed using an immunochromatographic lateral flow assay for differential qualitative detection of rotavirus (RoV), adenovirus (AdV), and norovirus genogroups I and II (NoVI, NoVII). Three-year (2017-2019) retrospective data on the cases of AGE reported at the hospitals were also collected and analysed. The overall prevalence of acute gastroenteritis was high (75.83%), with 13.19%representing viral co-infections. Rotavirus detection rate (69.17%) was higher than that for other viral agents (15.83%). Both mono- and mixed infections were observed for RoV, AdV and NoVII, whereas NoVI was detected only in co-infection cases. Analysis of risk factors showed that acute gastroenteritis was detected more often in infants of age ˂1 year (73.53%) than in those 1 ≤ 2 years (22.55%) or > 2 years (3.92%) in age. Gender and age were not associated with the cases of co-infections (p˂0.05). The seasonality data indicated one peak of the infection occurring in January 2017 which has decreased consecutively in the subsequent two years. These results demonstrate the prevalence and co-occurrence of enteric viruses in cases of infantile diarrhoea in Nsukka. Further molecular characterization of enteric virus strains, especially noroviruses, in this region would contribute significantly to global epidemiological data. Supplementary Information: The online version contains supplementary material available at 10.1007/s13337-023-00821-2.

A meta-analysis on the distribution of pathogenic Vibrio species in water sources and wastewater in Africa.

Vibrio species are waterborne ubiquitous organisms capable of causing diseases in humans and animals and the occurrence of infections caused by pathogenic Vibrio species among humans have increased globally. This reemergence is attributed to environmental impacts such as global warming and pollution. Africa is most vulnerable to waterborne infections caused by these pathogens because of lack of good water stewardship and management. This study was carried out to provide an in-depth inquiry into the occurrence of pathogenic Vibrio species in water sources and wastewater across Africa. In this regard, a systematic review and meta-analysis was conducted by searching five databases: PubMed, ScienceDirect, Google Scholar, Springer Search and African Journals Online (AJOL). The search yielded 70 articles on pathogenic Vibrio species presence in African aquatic environments that fit our inclusion criteria. Based on the random effects model, the pooled prevalence of pathogenic Vibrio species in various water sources in Africa was 37.6 % (95 % CI: 27.7-48.0). Eighteen countries were represented by the systematically assessed studies and their nationwide prevalence in descending order was: Nigeria (79.82 %), Egypt (47.5 %), Tanzania (45.8 %), Morocco (44.8), South Africa (40.6 %), Uganda (32.1 %), Cameroon (24.5 %), Burkina Faso (18.9 %) and Ghana (5.9 %). Furthermore, 8 pathogenic Vibrio species were identified across water bodies in Africa with the highest detection for V. cholerae (59.5 %), followed by V. parahaemolyticus (10.4 %), V.alginolyticus (9.8 %), V. vulnificus (8.5 %), V. fluvialis (6.6 %), V. mimicus (4.6 %), V. harveyi (0.5 %) and V. metschnikovii (0.1 %). Evidently, pathogenic Vibrio species occurrence in these water sources especially freshwater corroborates the continuous outbreaks observed in Africa. Therefore, there is an urgent need for proactive measures and continuous monitoring of water sources used for various purposes across Africa and proper treatment of wastewater before discharge into water bodies.