Norovirus-Associated Gastroenteritis Vesikari Score and Pre-Existing Salivary IgA in Young Children from Rural South Africa.

Norovirus (NoV) is the leading cause of viral gastroenteritis, mostly affecting young children worldwide. However, limited data are available to determine the severity of norovirus-associated AGE (acute gastroenteritis) and to correlate it with the NoV-specific IgA antibodies' level. Between October 2019 and September 2021, two hundred stool samples were randomly collected from symptomatic cases for the vesikari score and NoV-specific IgA assessment in young children from rural South Africa. Additionally, one hundred saliva specimens were concomitantly sampled within the same cohort to evaluate the NoV-specific salivary IgA levels. In addition, 50 paired saliva and stool samples were simultaneously collected from asymptomatic children to serve as controls. NoV strains in stool samples were detected using real-time RT-PCR, amplified, and genotyped with RT-PCR and Sanger sequencing. ELISA using NoV VLP (virus-like particles) GII.4 as antigens was performed on the saliva specimens. Dehydrated children were predominantly those with NoV infections (65/74, 88%; p < 0.0001). NoV-positive infections were significantly associated with the severe diarrhea cases having a high vesikari score (55%, 33/60) when compared to the non-severe diarrheal score (29.3%, 41/140; p < 0.0308). NoV of the GII genogroup was mainly detected in severe diarrhea cases (50.9%, 30/59; p = 0.0036). The geometric means of the NoV-specific IgA level were higher in the asymptomatic NoV-infected group (0.286) as compared to the symptomatic group (0.174). This finding suggests that mucosal immunity may not protect the children from the NoV infection. However, the findings indicated the contribution of the pre-existing NoV-specific IgA immune response in reducing the severity of diarrheal disease. A high vesikari score of AGE associated with the NoV GII genogroup circulating in the study area underscores the need for an appropriate treatment of AGE based on the severity level of NoV-associated clinical symptoms in young children.

Isoniazid and Rifampicin Resistance-Conferring Mutations in Mycobacterium tuberculosis Isolates from South Africa.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tb), remains a significant global health issue, with high morbidity and mortality rates. The emergence of drug-resistant strains, particularly multidrug-resistant TB (MDR-TB), poses difficult challenges to TB control efforts. This comprehensive review and meta-analysis investigated the prevalence of and molecular insights into isoniazid (INH) and rifampicin (RIF) resistance-conferring mutations in M. tb isolates from South Africa. Through systematic search and analysis of 11 relevant studies, we determined the prevalence of gene mutations associated with RIF and INH resistance, such as rpoB, katG, and inhA. The findings demonstrated a high prevalence of specific mutations, including S450L in rpoB, and S315T, which are linked to resistance against RIF and INH, respectively. These results contribute to the understanding of drug resistance mechanisms and provide valuable insights for the development of targeted interventions against drug-resistant TB.

Prevalence of Human Norovirus GII.4 Sydney 2012 [P31] between 2019 and 2021 among Young Children from Rural Communities in South Africa.

Acute gastroenteritis (AGE) accounts for considerable morbidity and mortality in the paediatric population worldwide, especially in low-income countries. Human norovirus (HNoV), particularly GII.4 strains, are important agents of AGE. This study aimed to detect and characterise HNoV in children with and without AGE. Between 2019 and 2021, 300 stool samples (200 AGE and 100 without AGE) were collected from children below 5 years of age referred to the healthcare facilities of the rural communities of Vhembe District, South Africa. After detection using real-time RT-PCR, HNoV positive samples were subjected to RT-PCR and Sanger sequencing. Partial nucleotide sequences (capsid/RdRp) were aligned using the Muscle tool, and phylogenetic analysis was performed using MEGA 11. The nucleotides' percent identity among HNoV strains was compared using ClustalW software. A significant difference in HNoV prevalence between AGE children (37%; 74/200) and non-AGE (14%; 14/100) was confirmed (p < 0.0001). Genogroup II (GII) HNoV was predominant in AGE children (80%; 59/74), whereas most non-AGE children were infected by the GI norovirus genogroup (64%; 9/14). GII.4 Sydney 2012 [P31] strains were dominant (59%; 19/32) during the study period. A phylogenetic analysis revealed a close relationship between the HNoV strains identified in this study and those circulating worldwide; however, ClustalW showed less than 50% nucleotide similarity between strains from this study and those from previously reported norovirus studies in the same region. Our findings indicate significant changes over time in the circulation of HNoV strains, as well as the association between high HNoV prevalence and AGE symptoms within the study area. The monitoring of HuNoV epidemiology, along with stringent preventive measures to mitigate the viral spread and the burden of AGE, are warranted.

Prevalence and Antimicrobial Resistance Profile of Diarrheagenic Escherichia coli from Fomites in Rural Households in South Africa.

Diarrheagenic Escherichia coli (DEC) pathotypes are the leading cause of mortality and morbidity in South Asia and sub-Saharan Africa. Daily interaction between people contributes to the spreading of Escherichia coli (E. coli), and fomites are a common source of community-acquired bacterial infections. The spread of bacterial infectious diseases from inanimate objects to the surrounding environment and humans is a serious problem for public health, safety, and development. This study aimed to determine the prevalence and antibiotic resistance of diarrheagenic E. coli found in toilets and kitchen cloths in the Vhembe district, South Africa. One hundred and five samples were cultured to isolate E. coli: thirty-five samples were kitchen cloths and seventy-five samples were toilet swabs. Biochemical tests, API20E, and the VITEK®-2 automated system were used to identify E. coli. Pathotypes of E. coli were characterised using Multiplex Polymerase Chain Reaction (mPCR). Nine amplified gene fragments were sequenced using partial sequencing. A total of eight antibiotics were used for the antibiotic susceptibility testing of E. coli isolates using the Kirby-Bauer disc diffusion method. Among the collected samples, 47% were positive for E. coli. DEC prevalence was high (81%), with ETEC (51%) harboring lt and st genes being the most dominant pathotype found on both kitchen cloths and toilet surfaces. Diarrheagenic E. coli pathotypes were more prevalent in the kitchen cloths (79.6%) compared with the toilet surfaces. Notably, hybrid pathotypes were detected in 44.2% of the isolates, showcasing the co-existence of multiple pathotypes within a single E. coli strain. The antibiotic resistance testing of E. coli isolates from kitchen cloths and toilets showed high resistance to ampicillin (100%) and amoxicillin (100%). Only E. coli isolates with hybrid pathotypes were found to be resistant to more than three antibiotics. This study emphasizes the significance of fomites as potential sources of bacterial contamination in rural settings. The results highlight the importance of implementing proactive measures to improve hygiene practices and antibiotic stewardship in these communities. These measures are essential for reducing the impact of DEC infections and antibiotic resistance, ultimately safeguarding public health.

Human Astrovirus in Symptomatic and Asymptomatic Children: A Cross-Sectional Study on Hospitalized and Outpatients from Rural Communities of South Africa between 2017-2021.

Human astroviruses are considered acute gastroenteritis agents (AGE) and are largely reported in children worldwide. There are limited data on astrovirus prevalence in rural communities, especially in hospitalized and asymptomatic cases. This study was a cross-sectional survey aiming to investigate the prevalence of classic human astroviruses in symptomatic and asymptomatic cases and hospitalized and outpatient children in rural communities of the Vhembe District, South Africa. A total of 236 stool samples (166 symptomatic and 70 asymptomatic) were collected from young children under 5 years of age. Real-time RT-PCR for astrovirus detection, RT-PCR amplification of capsid and polymerase partial genes as well as Sanger sequencing were performed. The classic astrovirus prevalence in symptomatic patients (7.23%, 12/166) as compared to healthy controls (4.29%, 3/70) was not statistically different (t-value: 1.782, p = 0.141: 95% CI). We did not observe a significant difference of classic astrovirus prevalence rate between the hospitalized group (6.52%, 3/46) and outpatient group (7.5%, 9/120). Symptomatic children below 6 months old were the most affected group (18.18%, 6/33). This study characterized human astrovirus genotype 2 and a putative recombinant strain (polymerase genotype 1/capsid genotype 2). Phylogenetic analysis revealed these genotypes are closely related to the strains circulating elsewhere within the African continent. The findings suggest that astrovirus is a common enteric pathogen in the study area. The results highlight the exposure of children and the need to monitor astroviruses for their potential impact in diarrhoeal diseases.

Predominance of Human Bocavirus Genotype 1 and 3 in Outpatient Children with Diarrhea from Rural Communities in South Africa, 2017-2018.

Human bocavirus (HBoV) is an emerging virus globally associated with diarrhea in young children. This study aims to investigate the prevalence of HBoV genotypes in children (≤5 years) from rural communities in South Africa (SA) suffering from acute gastroenteritis (AGE). A total of 141 fecal samples of children ≤5 years with acute gastroenteritis (AGE) were collected from rural primary health care facilities in the Vhembe district of SA between June 2017 and July 2018. Clinical symptoms and demographic data were also recorded. A total of 102 (72%) were outpatients, and 39 (28%) were hospitalized patients. Human bocavirus (HBoV) genotypes were determined using real-time multiplex PCR. DNA extracts of positive samples were confirmed by conventional PCR targeting the NS1 gene. Co-infection with other enteric viruses were determined in HBoV-positive samples using real-time PCR. HBoV was detected in eight (5.7%) children with AGE, of which three (37.5%) were HBoV1, three (37.5%) were HBoV3, and two (25%) were HBoV2. The majority of positive cases were identified in outpatients (62%) between the ages of 1 and 24 months. Co-infection in HBoV-positive samples with other enteric viruses included rotavirus (37.5%), adenovirus (37.5%), norovirus (25%), and astrovirus (12.5%). HBoV infections could be seen as a potential emerging diarrheal pathogen in South Africa. However, more studies are needed to understand the role of HBoV infections in children with AGE.

Prevalence of Human Bocavirus in Africa and Other Developing Countries between 2005 and 2016: A Potential Emerging Viral Pathogen for Diarrhea.

BACKGROUND: Human Bocavirus (HBoV) is an emerging virus discovered in 2005 from individuals suffering gastroenteritis and respiratory tract infections. Numerous studies related to the epidemiology and pathogenesis of HBoV have been conducted worldwide. This review reports on HBoV studies in individuals with acute gastroenteritis, with and without respiratory tract infections in Africa between 2005 and 2016. MATERIAL AND METHOD: The search engines of PubMed, Google Scholar, and Embase database for published articles of HBoV were used to obtain data between 2005 and 2016. The search words included were as follows: studies performed in Africa or/other developing countries or/worldwide; studies for the detection of HBoV in patients with/without diarrhea and respiratory tract infection; studies using standardized laboratory techniques for detection. RESULTS: The search yielded a total of 756 publications with 70 studies meeting the inclusion criteria. Studies included children and individuals of all age groups. HBoV prevalence in Africa was 13% in individuals suffering gastroenteritis with/without respiratory tract infection. CONCLUSION: Reports suggest that HBoV infections are increasingly being recognized worldwide. Therefore, surveillance of individuals suffering from infections in Africa is required to monitor the prevalence of HBoV and help understand the role of HBoV in individuals suffering from gastroenteritis with/without respiratory tract infection.

Prevalence of Human Sapovirus in Low and Middle Income Countries.

BACKGROUND: Sapovirus (SV) infection is a public health concern which plays an important role in the burden of diarrhoeal diseases, causing acute gastroenteritis in people of all ages in both outbreaks and sporadic cases worldwide. OBJECTIVE/STUDY DESIGN: The purpose of this report is to summarise the available data on the detection of human SV in low and middle income countries. A systematic search on PubMed and ScienceDirect database for SV studies published between 2004 and 2017 in low and middle income countries was done. Studies of SV in stool and water samples were part of the inclusion criteria. RESULTS: From 19 low and middle income countries, 45 published studies were identified. The prevalence rate for SV was 6.5%. A significant difference (P=0) in SV prevalent rate was observed between low income and middle income countries. Thirty-three (78.6%) of the studies reported on children and 8 (19%) studies reported on all age groups with diarrhoea. The majority (66.7%) of studies reported on hospitalised patients with acute gastroenteritis. Sapovirus GI was shown as the dominant genogroup, followed by SV-GII. CONCLUSION: The detection of human SV in low and middle income countries is evident; however the reports on its prevalence are limited. There is therefore a need for systematic surveillance of the circulation of SV, and their role in diarrhoeal disease and outbreaks, especially in low and middle income countries.

Genetic characterisation of Norovirus strains in outpatient children from rural communities of Vhembe district/South Africa, 2014-2015.

BACKGROUND: Norovirus (NoV) is now the most common cause of both outbreaks and sporadic non-bacterial gastroenteritis worldwide. However, data supporting the role of NoV in diarrheal disease are limited in the African continent. OBJECTIVES: This study investigates the distribution of NoV genotypes circulating in outpatient children from rural communities of Vhembe district/South Africa. STUDY DESIGN: Stool specimens were collected from children under five years of age with diarrhea, and controls without diarrhea, between July 2014 and April 2015. NoV-positive samples, detected previously by Realtime PCR, were analysed using conventional RT-PCR targeting the partial capsid and polymerase genes. Nucleotide sequencing methods were performed to genotype the strains. RESULTS: The sequence analyses demonstrated multiple NoV genotypes including GI.4 (13.8%), GI.5 (6.9%), GII.14 (6.9%), GII.4 (31%), GII.6 (3.4%), GII.P15 (3.4%), GII.P21 (3.4%) and GII.Pe (31%). The most prevalent NoV genotypes were GII.4 Sydney 2012 variants (n=7) among the capsid genotypes, GII.Pe (n=9) among the polymerase genotypes and GII.Pe/GII.4 Sydney 2012 (n=8) putative recombinants among the RdRp/Capsid genotypes. Two unassigned GII.4 variants were found. CONCLUSIONS: The findings highlighted NoV genetic diversity and revealed continuous pandemic spread and predominance of GII.Pe/GII.4 Sydney 2012, indicative of increased NoV activity. An unusual RdRp genotype GII.P15 and two unassigned GII.4 variants were also identified from rural settings of the Vhembe district/South Africa. NoV surveillance is warranted to help to inform investigations into NoV evolution and disease burden, and to support on-going vaccine development programmes.

Norovirus prevalence and estimated viral load in symptomatic and asymptomatic children from rural communities of Vhembe district, South Africa.

BACKGROUND: Human Norovirus (NoV) is recognized as a major etiological agent of sporadic acute gastroenteritis worldwide. OBJECTIVES: This study describes the clinical features associated with Human NoV occurrence in children and determines the prevalence and estimated viral burden of NoV in symptomatic and asymptomatic children in rural South Africa. STUDY DESIGN: Between July 2014 and April 2015, outpatient children under 5 years of age from rural communities of Vhembe district, South Africa, were enrolled for the study. A total of 303 stool specimens were collected from those with diarrhea (n=253) and without (n=50) diarrhea. NoVs were identified using real-time one-step RT-PCR. RESULTS: One hundred and four (41.1%) NoVs were detected (62[59.6%] GII, 16[15.4%] GI, and 26[25%] mixed GI/GII) in cases and 18 (36%) including 9(50%) GII, 2(11.1%) GI and 7(38.9%) mixed GI/GII in controls. NoV detection rates in symptomatic and asymptomatic children (OR=1.24; 95% CI 0.66â¿¿2.33) were not significantly different. Comparison of the median CT values for NoV in symptomatic and asymptomatic children revealed significant statistical difference of estimated GII viral load from both groups, with a much higher viral burden in symptomatic children. CONCLUSIONS: Though not proven predictive of diarrhea disease in this study, the high detection rate of NoV reflects the substantial exposure of children from rural communities to enteric pathogens possibly due to poor sanitation and hygiene practices. The results suggest that the difference between asymptomatic and symptomatic children with NoV may be at the level of the viral load of NoV genogroups involved.

Human Norovirus prevalence in Africa: a review of studies from 1990 to 2013.

OBJECTIVES: To assess the contribution of Human Norovirus to diarrhoeal diseases in Africa. METHODS: We conducted a systematic review of the PubMed and EMBASE databases for published articles of Human Norovirus in Africa between 1990 and 2013. Data were extracted from selected studies and analysed. RESULTS: A total of 208 eligible studies were identified, of which 55 (from 19 countries) met the inclusion criteria. Many cases were of sporadic gastroenteritis (70.9%) in children (82%), 65.4% of which were seen in an outpatient setting. Over half (59.4%) of the affected children were under 5 years of age. The pooled prevalence rate of Human NoV was 11% (95% CI 8-14%), and the meta-analysis indicated significant heterogeneity between the studies. However, the conditional negative binomial regression could not clearly find the factors affecting the Human NoV prevalence rates reported. A close relationship was found between Human Norovirus strains from environmental and clinical samples. CONCLUSION: Unreported sporadic gastroenteritis cases of Human Norovirus are common in Africa. Most are community-associated infections. Possible environmental transmission routes have been documented. Combined environmental and clinical studies are required for targeted actions to control transmission of Human Norovirus in Africa. Systematic surveillance of Human Norovirus is needed to measure the burden of Norovirus-induced gastroenteritis in Africa and support any requirements for vaccine development.

Short-term antiretroviral therapy fails to reduce the expanded activated CCR5-expressing CD4+ T lymphocyte population or to restore the depleted naive population in chronically HIV-infected individuals with active pulmonary tuberculosis.

The effective role of antiretroviral (ARV) therapy in the regulation of CD4 T cell subset distribution, coreceptor expression, and activation status in individuals with chronic HIV also presenting with active pulmonary TB is not clearly understood. A cross-sectional analysis was performed on a total of 137 South African individuals. CCR5, CXCR4, and CD38 expression of CD4 T cell subsets in HIV-infected individuals with and without active pulmonary tuberculosis (TB) disease, pre- and post-ARV therapy, were determined by flow cytometry. In treatment-naive patients, CD4 T cells showed elevated surface expression of CCR5 and CD38 in TB/HIV coinfection as compared to HIV infection alone despite the overall percentage of CD4 T cells expressing CCR5 being reduced. Total CD38+ CD4 T cells were not significantly increased in either group; however, mean CD38 fluorescence was significantly higher in the context of TB infection. HIV/TB-coinfected individuals also displayed an increased percentage of activated (CD38+) CCR5+ CD4 T cells as compared to HIV patients alone. The naive CD4 T cell subset was depleted similarly in both HIV and HIV/TB groups. Only the HIV treatment group and not the TB-coinfected treatment group showed significantly decreased activated CCR5+ CD4 T cells, an increased percentage of naive T cells, and a decreased percentage of antigen-experienced T cells. This study highlighted an association of TB disease with immune activation, particularly of the CCR5+ CD4 T cell subset in HIV infection and the differential impact of ARV treatment. Further studies are needed to understand how TB coinfection confounds normal responses to ARV.

New enteroviruses, EV-93 and EV-94, associated with acute flaccid paralysis in the Democratic Republic of the Congo.

Surveillance of acute flaccid paralysis often identifies enteroviruses not typeable by virus neutralization in cell culture. During 2000 and 2001, 186 isolates from 138 children with acute flaccid paralysis in the Democratic Republic of the Congo were sent for typing to the National Reference Centre for Enteroviruses in Lyon, France. The 5' UTR of the viral genome could be amplified by PCR for 158 isolates from 114 patients. Isolates from 89 patients were neutralizable, and contained non-polio enterovirus types. Seventeen children were infected with more than one entero- or adenovirus; another three were co-infected with both these viruses. Serological typing failed with 19 isolates from 13 (9%) patients. The VP1 region of these strains could be amplified by PCR and sequenced, which revealed that five children were infected with CV-A17, EV-70, EV-76, EV-77, or CV-A13. Two patients were doubly infected, one with CV-A24 and E-9, and another with E-27 and EV-81. Isolates from six children contained strains with divergent VP1 region. The amino acid sequences of these complete VP1 regions diverged >or=28% from published types indicating that they represented two new enterovirus types, tentatively designated EV-93 belonging to HEV-B and EV-94 within HEV-D. The latter enterovirus has in parallel been isolated from sewage in Egypt. In conclusion, there was a high frequency of "untypable" enterovirus isolates from cases with acute flaccid paralysis in the Democratic Republic of the Congo. Six of these were shown to represent two enteroviruses not previously described.

G8 rotavirus strains isolated in the Democratic Republic of Congo belong to the DS-1-like genogroup.

Several G8P[6] and G8P[8] rotavirus strains were isolated from hospitalized patients in the Democratic Republic of Congo in 2003. To investigate their overall genomic relatedness and to determine to which genogroup they belonged, the complete genomes of strains DRC88 (G8P[8]) and DRC86 (G8P[6]) were determined. Genomic comparison of these two African G8 strains revealed that 10 out of their 11 gene segments, except for VP4, were nearly identical (>98.9% identical at the nucleotide level), suggesting that this rare G8P[8] rotavirus strain originated recently from a reassortment between a common G8P[6] strain and a strain with a P[8] specificity. A very close evolutionary relationship between 9 out of the 11 gene segments of DRC88 and DRC86 and rotavirus strains belonging to the DS-1-like (G2P[4]) "genogroup" was found, and several possible reassortment events preceding the occurrence of G8P[8] and G8P[6] human rotaviruses were hypothesized. Since the genes of G2P[4] rotavirus strains are very well adapted to infect humans, the acquirement of a new VP7 (G8) gene, and especially the replacement of P[6] (believed to be of animal origin) by P[8] (most common in human rotaviruses), might make DRC88-like rotaviruses very well equipped to become a predominant human rotavirus strain and an important pathogen on the African continent and the rest of the world. These findings have important implications for rotavirus vaccine development and highlight that typing of new rotavirus strains by merely sequencing their VP7 and VP4 genes provides us with only the tip of the iceberg regarding rotavirus diversity.