Impact of rotavirus vaccination on rotavirus hospitalisation rates among a resource-limited rural population in Mbita, Western Kenya.

OBJECTIVES: A two-dose oral monovalent rotavirus vaccine (RV1) was introduced into the Kenyan National Immunization Program in July 2014. We assessed trends in hospitalisation for rotavirus-specific acute gastroenteritis (AGE) and strain distribution among children <5 years in a rural, resource-limited setting in Kenya before and after the nationwide implementation of the vaccine. METHODS: Data on rotavirus AGE and strain distribution were derived from a 5-year hospital-based surveillance. We compared rotavirus-related hospitalisations and strain distribution in the 2-year post-vaccine period with the 3-year pre-vaccine baseline. Vaccine administrative data from the Unit of Vaccines and Immunization Services (UVIS) for Mbita sub-county were used to estimate rotavirus immunisation coverage in the study area. RESULTS: We observed a 48% (95% CI: 27-64%) overall decline in rotavirus-related hospitalisations among children aged <5 years in the post-vaccine period. Coverage with the last dose of rotavirus vaccine increased from 51% in year 1% to 72% in year 2 of the vaccine implementation. Concurrently, reductions in rotavirus hospitalisations increased from 40% in the first year to 53% in the second year of vaccine use. The reductions were most pronounced among the vaccine-eligible group, with the proportion of cases in this age group dropping to 14% in post-vaccine years from a high of 51% in the pre-vaccine period. A diversity of rotavirus strains circulated before the introduction of the vaccine with G1P[8] being the most dominant strain. G2P[4] replaced G1P[8] as the dominant strain after the vaccine was introduced. CONCLUSIONS: Rotavirus vaccination has resulted in a notable decline in hospital admissions for rotavirus infections in a rural resource-limited population in Kenya. This provides early evidence for continued use of rotavirus vaccines in routine childhood immunisations in Kenya. Our data also underscore the need for expanding coverage on second dose so as to maximise the impact of the vaccine.

Molecular epidemiology of rotavirus gastroenteritis in Central Kenya before vaccine introduction, 2009-2014.

Between July 2009 and June 2014, a total of 1,546 fecal specimens were collected from children <5 years of age with acute gastroenteritis admitted to Kiambu County Hospital, Central Kenya. The specimens were screened for group A rotavirus (RVA) using ELISA, and RVA-positive specimens were subjected to semi-nested RT-PCR to determine the G and P genotypes. RVA was detected in 429/1,546 (27.5%) fecal specimens. RVA infections occurred in all age groups <59 months, with an early peak at 6-17 months. The infections persisted year-round with distinct seasonal peaks depending on the year. G1P[8] (28%) was the most predominant genotype, followed by G9P[8] (12%), G8P[4] (7%), G1P[4] (5%), G9P[4] (4%), and G12P[6] (3%). In the yearly change of G and P genotypes, a major shift from G9P[8] to G1P[8] was found in 2012. Phylogenetic analysis of the nucleotide sequences of the VP7 and VP4 genes of seven strains with unusual G8 or P[6] showed that the VP7 nucleotide sequences of G8 were clustered in lineage 6 in which African strains are included, and that there are at least two distinct VP4 nucleotide sequences of P[6] strains. These results represent basic data on RVA strains circulating in this region before vaccine introduction. J. Med. Virol. 89:809-817, 2017. © 2016 Wiley Periodicals, Inc.

Genetic characterization of group A rotavirus in children with acute gastroenteritis in Kericho County Referral Hospital, Kenya.

Introduction: approximately over 80% of mortalities due to rotavirus occur in countries that have limited resources, especially in sub-Saharan Africa and South Asia. The study was intended to determine the genetic characteristics of rotavirus A in children exhibiting gastroenteritis at Kericho County Referral Hospital. Methods: the study design was cross-sectional. Consecutive sampling was engaged obtaining a sample size of 200 stool samples. Genetic characterization of group A rotavirus strains was done using Enzyme-Linked Immunosorbent Assay. Positive samples underwent Sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Afterwards viewing of the RNA double strands of the rotavirus genome in gels was done using Silver Nitrate. The positive samples underwent RT-PCR amplification followed by sequencing on the pieces of the VP7 or VP4 gene obtained. Results: one hundred and six (53%) samples from males and 94 (47%) from females. Twenty-three samples were positive hence a prevalence of 11.5%. The most affected demographics were children of guardians with secondary school education (51%). The most affected social economic status was housewives (46.5%). The most affected age was 21-30 months at 26.5%. Long electropherotypes were in 22 samples (96%). The G3 genotype of rotavirus A was prevalent 16/23 (69.57%). Conclusion: rotavirus prevalence was 11.5%. The G3 genotype was the most prevalent in circulation. The occurrence of non-typable strains indicated that the strains may be diversified emphasizing the need to include emerging strains within the vaccines in use. Hence the need to continuously monitor the effects in older children.

Long-term impact of rotavirus vaccination on all-cause and rotavirus-specific gastroenteritis and strain distribution in Central Kenya: An 11-year interrupted time-series analysis.

BACKGROUND: Kenya introduced a monovalent rotavirus vaccine administered orally at 6 and 10 weeks of age into her National Immunization Program in July 2014. The study evaluated the long-term impact of the vaccine on hospitalization for all-cause and rotavirus-specific acute gastroenteritis (AGE) and strain epidemiology in Kenya. METHODS: Data on all-cause and rotavirus-specific AGE and strain distribution were derived from an eleven-year hospital-based surveillance of AGE among children aged <5 years at Kiambu County Teaching and Referral Hospital (KCTRH) in Central Kenya between 2009 and 2020. Fecal samples were screened for group A rotavirus using ELISA and genotyped using multiplex semi-nested RT-PCR. Trends in all-cause and rotavirus-related AGE and strain distribution were compared between the pre-vaccine (July 2009-June 2014), early post-vaccine (July 2014-June 2016) and late post-vaccine (February 2019-October 2020) periods. RESULTS: Rotavirus-specific AGE was detected at 27.5% (429/1546, 95% CI: 25.5-30.1%) in the pre-vaccine period; 13.8% (91/658, 95% CI: 11.3-16.6%) in the early post-vaccine period (July 2014-June 2016); and 12.0% (229/1916, 95% CI: 10.6-13.5%) in the late post-vaccine period (February 2019-October 2020). This amounted to a decline of 49.8% (95% CI: 34.6%-63.7%) in rotavirus-specific AGE in the early post-vaccine period and 53.4% (95% CI: 41.5-70.3%) in the late post-vaccine period when compared to the pre-vaccine period. All-cause AGE hospitalizations declined by 40.2% (95% CI: 30.8%-50.2%) and 75.3% (95% CI: 65.9-83.1%) in the early post-vaccine and late post-vaccine periods, respectively, when compared to the pre-vaccine period. G3P [8] was the predominant strain in the late post-vaccine period, replacing G1P[8] which had predominated in the pre-vaccine and early post-vaccine periods. Additionally, we detected considerable proportions of uncommon strains G3P[6] (4.8%) and G12P[6] (3.5%) in the post-vaccine era. CONCLUSION: Rotavirus vaccination has resulted in a significant decline in all-cause and rotavirus-specific AGE, and thus, provides strong evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunization. However, the shift in strain dominance and age distribution of rotavirus AGE in the post-vaccine era underscores the need for continued surveillance to assess any possible vaccine-induced selective pressure that could diminish the vaccine effectiveness over time.

Whole-genome analysis reveals the complex evolutionary dynamics of Kenyan G2P[4] human rotavirus strains.

Although G2P[4] rotaviruses are common causes of acute childhood diarrhoea in Africa, to date there are no reports on whole genomic analysis of African G2P[4] strains. In this study, the nearly complete genome sequences of two Kenyan G2P[4] strains, AK26 and D205, detected in 1982 and 1989, respectively, were analysed. Strain D205 exhibited a DS-1-like genotype constellation, whilst strain AK26 appeared to be an intergenogroup reassortant with a Wa-like NSP2 genotype on the DS-1-like genotype constellation. The VP2-4, VP6-7, NSP1, NSP3 and NSP5 genes of strain AK26 and the VP2, VP4, VP7 and NSP1-5 genes of strain D205 were closely related to those of the prototype or other human G2P[4] strains. In contrast, their remaining genes were distantly related, and, except for NSP2 of AK26, appeared to originate from or share a common origin with rotavirus genes of artiodactyl (ruminant and camelid) origin. These observations highlight the complex evolutionary dynamics of African G2P[4] rotaviruses.

Full genomic analysis of a G8P[1] rotavirus strain isolated from an asymptomatic infant in Kenya provides evidence for an artiodactyl-to-human interspecies transmission event.

Group A rotavirus (GAR) G8P[1] strains, found sometimes in cattle, have been reported rarely from humans. Therefore, analysis of the full genomes of human G8P[1] strains are of significance in the context of studies on interspecies transmission of rotaviruses. However, to date, only partial-length nucleotide sequences are available for the 11 genes of a single human G8P[1] strain, while the partial sequences of two other strains have been reported. The present study reports the first complete genome sequence of a human G8P[1] strain, B12, detected from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the full-length nucleotide sequences of VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5 genes of strain B12 were assigned to G8-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3 genotypes, respectively. Each of the 11 genes of strain B12 appeared to be more related to cognate genes of artiodactyl (ruminant and/or camelid) and/or artiodactyl-derived human GAR strains than those of most other rotaviruses. Strain B12 exhibited low levels of genetic relatedness to canonical human GAR strains, such as Wa and DS-1, ruling out the possibility of its origin from reassortment events between artiodactyl-like human and true human strains. These observations suggest that strain B12 might have been directly transmitted from artiodactyls to humans. Unhygienic conditions and close proximity of humans to livestock at the sampling site might have facilitated this rare event. This is the first report on a full genomic analysis of a rotavirus strain from Kenya. To our knowledge, strain B12 might be the oldest G8 strain characterized molecularly from the Africa continent.

Characterization of human rotavirus strains from children with diarrhea in Nairobi and Kisumu, Kenya, between 2000 and 2002.

Rotavirus infection is a major cause of diarrheal illness and hospitalization in children <5 years old in Kenya and has been described in various settings and locations across the country and for different time points. In this study, we expand on the molecular characterization of rotavirus strains collected in Nairobi and Kisumu, Kenya, between 2000 and 2002. Rotavirus strains were typed by reverse-transcription polymerase chain reaction and characterized using VP6 monoclonal antibodies and RNA electrophoresis of the viral genome. A large proportion of specimens could not be genotyped; 41% did not produce a G type result, and 43% did not produce a P type result. Of the strains that could be genotyped, G1P[8] strains were predominant, followed by G2P[4] strains. In addition, G8 and G9 strains were seen in similar proportions Interestingly, the G and P combinations were more diverse among G8 and G9 rotavirus strains, suggesting the recent introduction of these strains into the human population. These observations are a link between the occasional observation of G8 and G9 strains at the turn of the century and the high predominance of G9P[8] strains observed in Kenya in 2005.

Determination of the G and P types of previously nontypeable rotavirus strains from the African Rotavirus Network, 1996-2004: Identification of unusual G types.

A total of 215 nontypeable rotavirus samples collected from children <5 years of age by members of the African Rotavirus Network were characterized using reverse-transcription polymerase chain reaction analysis and sequencing. The most predominant strain identified was P[8]G1 (46.9%). Genotypes P[8]G10, P[8]G8, P[6]G8, and P[7]G5 were also detected at frequencies varying from 0.5% to 2.3%. This study suggests that reassortment of unusual G types into a background of globally common genotype P[8] strains may be a major mechanism of generating rotavirus diversity. Nucleotide substitutions at the P[8], P[6], and G1 primer binding sites accounted for the failure to type these strains initially. Hence, these findings highlight the need for regular evaluation of rotavirus genotyping methods.

Emergence and characterization of serotype G9 rotavirus strains from Africa.

Serotype G9 strains have been detected sporadically and in localized outbreaks in various African countries, including South Africa, Botswana, Malawi, Kenya, Cameroon, Nigeria, Ghana, Guinea-Bissau, Libya, and Mauritius. Serotype G9 strains were analyzed to investigate genogroup characteristics, including subgroup specificity, electropherotype, and P and G genotypes. In addition, the antigenic composition of the South African G9 strains was assessed. African G9 strains were associated with both DS-1-like characteristics and Wa-like characteristics, indicating the predisposition of G9 strains to frequently reassort. Despite these reassortment events, serotype G9 strains appear to maintain antigenic character in the outer capsid protein, as evident with the reaction of the South African G9 strains with the G9-specific monoclonal antibody F45:1. Phylogenetic analysis clustered African G9 strains geographically, regardless of genogroup characteristics, into 1 lineage (IIId). Two groups of G9 strains, originating in India and Japan, were identified in this lineage. Continuous surveillance of circulating rotavirus strains in Africa is vital to prepare for future vaccine implementation on a continent that clearly needs such preventative medicines.

Genomic characterization of an African G4P[6] human rotavirus strain identified in a diarrheic child in Kenya: Evidence for porcine-to-human interspecies transmission and reassortment.

Human rotavirus strains having the unconventional G4P[6] genotype have been sporadically identified in diarrheic patients in different parts of the world. However, the whole genome of only one human G4P[6] strain from Africa (central Africa) has been sequenced and analyzed, and thus the exact origin and evolutionary pattern of African G4P[6] strains remain to be elucidated. In this study, we characterized the full genome of an African G4P[6] strain (RVA/Human-wt/KEN/KCH148/2019/G4P[6]) identified in a stool specimen from a diarrheic child in Kenya. Full genome analysis of strain KCH148 revealed a unique Wa-like genogroup constellation: G4-P[6]-I1-R1-C1-M1-A1-N1-T7-E1-H1. NSP3 genotype T7 is commonly found in porcine rotavirus strains. Furthermore, phylogenetic analysis showed that 10 of the 11 genes of strain KCH148 (VP7, VP4, VP6, VP1-VP3, NSP1, and NSP3-NSP5) appeared to be of porcine origin, the remaining NSP2 gene appearing to be of human origin. Therefore, strain KCH148 was found to have a porcine rotavirus backbone and thus is likely to be of porcine origin. Furthermore, strain KCH148 is assumed to have been derived through interspecies transmission and reassortment events involving porcine and human rotavirus strains. To our knowledge, this is the first report on full genome-based characterization of a human G4P[6] strain from east Africa. Our observations demonstrated the diversity of human G4P[6] strains in Africa, and provide important insights into the origin and evolutionary pattern of zoonotic G4P[6] strains on the African continent.

Characterization of genotype G8 strains from Malawi, Kenya, and South Africa.

Reviews of the global distribution of rotavirus genotypes have revealed the continuous circulation of G8 strains in Africa, often responsible for more cases of rotavirus disease than the more common G1-G4 rotavirus strains. During the study, genotype G8 strains from Malawi, Kenya, and South Africa were detected and the VP7 and VP4 genes of selected specimens were sequenced. Results indicated that G8 strains appeared to reassort frequently and were associated with P[6], P[4], and P[8] specificity. Phylogenetic analysis suggested that G8 strains occurred in a North/South African phylogenetic divide. In addition, G8 strains appear to be able to infect non-human primates and strains with close phylogenetic relationships were detected in the same year on two continents. Any rotavirus vaccine introduced into African environments will need to demonstrate protective efficacy against unusual genotype combinations, new serotypes, and animal strains. Therefore, continuous monitoring of rotavirus strains in human and animal populations in Africa is a necessity.

Post-vaccine rotavirus genotype distribution in Nairobi County, Kenya.

BACKGROUND: Rotaviruses are primary etiological agents of gastroenteritis in young children. In Kenya, G1P8 monovalent vaccine (Rotarix) was introduced in July 2014 for mandatory vaccination of all newborns at 6 and 10 weeks of age. Since then, no studies have been done to identify the rotavirus genotypes circulating in Nairobi County, Kenya, following the vaccine introduction, hence the post-vaccine genotype distribution is not known. OBJECTIVES: The aim of this study was to determine the post-vaccine occurrence of rotavirus genotypes in children <5 years of age in Nairobi County, Kenya. METHODS: Stool samples were collected from children presenting with diarrhea for whom the vaccination status was card-confirmed. Fecal samples were analyzed for rotavirus antigen using a commercial enzyme immunoassay (EIA) kit, followed by characterization by polyacrylamide gel electrophoresis, RT-PCR, and nested PCR genotyping, targeting the most medically important genotypes. RESULTS: The strains observed included G1P[8] (38.8%), G9P[8] (20.4%), G2P[4] (12.2%), G3[P4] (6.1%), G2P[6] (4.1%), and G9P[6] (4.1%). Mixed genotype constellations G3P[4][8] were also detected (4.1%). Remarkably, an increased prevalence of G2 genotypes was observed, revealing a change in genetic diversity of rotavirus strains. While the dominance of G1P[8] decreased after vaccination, an upsurge in G2P[4] (12.2%) and G9P[8] (20.4%) was observed. Additionally, G3[P4] (6.1%) and G2P[6] (4.1%) prevalence increased over the 3 years of study. CONCLUSIONS: The results inform the need for robust longitudinal surveillance and epidemiological studies to assess the long-term interaction between rotavirus vaccine and strain ecology.

Feasibility of the Bag-Mediated Filtration System for Environmental Surveillance of Poliovirus in Kenya.

The bag-mediated filtration system (BMFS) was developed to facilitate poliovirus (PV) environmental surveillance, a supplement to acute flaccid paralysis surveillance in PV eradication efforts. From April to September 2015, environmental samples were collected from four sites in Nairobi, Kenya, and processed using two collection/concentration methodologies: BMFS (> 3 L filtered) and grab sample (1 L collected; 0.5 L concentrated) with two-phase separation. BMFS and two-phase samples were analyzed for PV by the standard World Health Organization poliovirus isolation algorithm followed by intratypic differentiation. BMFS samples were also analyzed by a cell culture independent real-time reverse transcription polymerase chain reaction (rRT-PCR) and an alternative cell culture method (integrated cell culture-rRT-PCR with PLC/PRF/5, L20B, and BGM cell lines). Sabin polioviruses were detected in a majority of samples using BMFS (37/42) and two-phase separation (32/42). There was statistically more frequent detection of Sabin-like PV type 3 in samples concentrated with BMFS (22/42) than by two-phase separation (14/42, p = 0.035), possibly due to greater effective volume assayed (870 mL vs. 150 mL). Despite this effective volume assayed, there was no statistical difference in Sabin-like PV type 1 and Sabin-like PV type 2 detection between these methods (9/42 vs. 8/42, p = 0.80 and 27/42 vs. 32/42, p = 0.18, respectively). This study demonstrated that BMFS can be used for PV environmental surveillance and established a feasible study design for future research.

Rotavirus prevalence and seasonal distribution post vaccine introduction in Nairobi county Kenya.

Rotaviruses are one of the leading etiological agents of gastroenteritis in young children, for which a monovalent G1P(8) vaccine has been provided for free in Kenyan since July 2014. The main objective was to estimate the post vaccine prevalence and seasonal distribution of rotavirus diarrhea in children less than 5 years in Nairobi County, Kenya. Rotavirus positive samples were collected from children below 5 years of age in two hospitals within Nairobi County where vaccination status was card-confirmed. The children were examined and the demographic and clinical profiles of the children were recorded. Fecal specimens were analyzed for rotavirus antigen using an ELISA kit, followed by characterization by PAGE. Out of the total 323 samples, 49 had detectable rotavirus infection, representing 15.2% prevalence. Age distribution of rotavirus prevalence was as follows: ≤ 6 months-8.5%, 7-12 months-27.4%, 13-24 months - 41.4%, 25-36 months - 16.4% while 36-65 months had 6.3%. Rotavirus diarrhea was more common in wet and cold months of the year, the highest prevalence being observed in August (24.5%), 12.3% in both July and March, while April scored a prevalence of 10.2%. Out of the 49 rotavirus positive children, 48 had vomiting and abdominal cramps while all had fever and watery stool. The prevalence of Rotaviral diarrhea in children less than 5 years in Nairobi County Kenya has greatly reduced following the vaccine introduction and is more common during the wet and cold seasons of the year.

Prevalence of Clostridium difficile infections among Kenyan children with diarrhea.

BACKGROUND: Diarrhea causes significant morbidity and mortality among children worldwide. Regions most affected by diarrhea include Sub-Saharan Africa and Southeast Asia, where antibiotics are in common use and can make children more vulnerable to Clostridium difficile and pathogens that are not affected by these drugs. Indeed, C. difficile is a major diarrhea-associated pathogen and poses a significant threat to vulnerable and immunocompromised populations. Yet, little is known about the role and epidemiology of C. difficile in diarrhea-associated illness among young children. As a result, C. difficile is often neglected in regions such as Sub-Saharan Africa that are most impacted by childhood diarrhea. The purpose of this study was to establish the frequency of C. difficile in young children (<5 years) with diarrhea. METHODS: Children presenting with diarrhea at a national hospital in Kenya from 2015 to 2018 were enrolled consecutively. Following informed consent by a parent or legal guardian, stool samples were obtained from the children and demographic data were collected. The stools were examined for the presence of four common pathogens known to cause diarrhea: C. difficile, rotavirus, Cryptosporidium parvum, and Giardia lamblia. C. difficile was verified by toxigenic culture and PCR. The presence of C. parvum and/or G. lamblia was determined using the ImmunoCard STAT! Crypto/Giardia Rapid assay. Rotavirus was detected by ELISA. RESULTS: The study population comprised 157 children; 62.4% were male and 37.6% were female and their average age was 12.4 months. Of the 157 stool specimens investigated, 37.6% were positive for C. difficile, 33.8% for rotavirus, 5.1% for Cryptosporidium, and 5.1% for Giardia. PCR analysis identified at least one of the C. difficile-specific - genes (tcdA, tcdB, or tcdC). Further, 57.6% of the stools had C. difficile colonies bearing a frame-shift deletion in the tcdC gene, a mutation associated with increased toxin production. The frequency of C. difficile was 32.6% in children ≤12 months old and increased to 46.6% in children 12-24 months old. CONCLUSIONS: In Kenyan children presenting with diarrhea, C. difficile is more prevalent than rotavirus or Cryptosporidium, two leading causes of childhood diarrhea. These findings underscore the need to better understand the role of C. difficile in children with diarrhea, especially in areas with antibiotic overuse. Understanding C. difficile epidemiology and its relationship to co-infecting pathogens among African children with diarrhea will help in devising ways of reducing diarrhea-associated illness.

Genomic characterization of uncommon human G3P[6] rotavirus strains that have emerged in Kenya after rotavirus vaccine introduction, and pre-vaccine human G8P[4] rotavirus strains.

A monovalent rotavirus vaccine (RV1) was introduced to the national immunization program in Kenya in July 2014. There was increased detection of uncommon G3P[6] strains that coincided temporally with the timing of this vaccine introduction. Here, we sequenced and characterized the full genomes of two post-vaccine G3P[6] strains, RVA/Human-wt/KEN/KDH1951/2014/G3P[6] and RVA/Human-wt/KEN/KDH1968/2014/G3P[6], as representatives of these uncommon strains. On full-genomic analysis, both strains exhibited a DS-1-like genotype constellation: G3-P[6]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Phylogenetic analysis revealed that all 11 genes of strains KDH1951 and KDH1968 were very closely related to those of human G3P[6] strains isolated in Uganda in 2012-2013, indicating the derivation of these G3P[6] strains from a common ancestor. Because the uncommon G3P[6] strains that emerged in Kenya are fully heterotypic as to the introduced vaccine strain regarding the genotype constellation, vaccine effectiveness against these G3P[6] strains needs to be closely monitored.

Detection of potentially pathogenic enteric viruses in environmental samples from Kenya using the bag-mediated filtration system.

Enteric virus environmental surveillance via a highly sensitive method is critical, as many enteric viruses have low infectious doses and can persist in the environment for extended periods. This study determined the potential of the novel bag-mediated filtration system (BMFS) to recover human enteric viruses and pepper mild mottle virus (PMMoV) from wastewater and wastewater-impacted surface waters, examined PMMoV use as a fecal contamination indicator in Kenya, and identified potential BMFS process controls. From April 2015 to April 2016, BMFS samples were collected from seven sites in Kenya (n = 59). Enteroviruses and PMMoV were detected in 100% of samples, and human adenovirus, human astrovirus, hepatitis A virus, norovirus GI, norovirus GII, sapovirus, and human rotavirus were detected in the majority of samples. The consistent detection of enteroviruses and PMMoV suggests that these viruses could be used as indicators in similarly fecally contaminated sites and BMFS process controls. As contamination of surface water sources remains a global issue, enteric virus environmental surveillance is necessary. This study demonstrates an effective way to sample large volumes of wastewater and wastewater-impacted surface waters for the detection of multiple enteric viruses simultaneously.

The epidemiology of human rotavirus associated with diarrhoea in Kenyan children: a review.

Rotavirus gastroenteritis still remains a major cause of morbidity and mortality among young children in developing countries, with approximately 150,000-200,000 deaths occurring annually in sub-Saharan Africa. We reviewed papers published over the last 30 years on the epidemiology of rotavirus diarrhoea among the hospitalized and out-patient children in Kenya. The analysis shows rotavirus prevalence of 6-56% with diarrhoea occurring throughout the year and generally exhibiting distinct peaks during the dry months. Among the common genotype, G1 was the most predominant up to the year 2002 but more recently there has been an emergence of genotype G9 as the most predominant genotype and to a less extent G8. It is important to continue rotavirus surveillance in Kenya to determine accurately the burden of rotavirus disease and the emerging new genotypes. This will assist policy makers in decision making on rotavirus vaccine introduction and determining the impact of the vaccine.

Improvement of the Bag-Mediated Filtration System for Sampling Wastewater and Wastewater-Impacted Waters.

Environmental surveillance of poliovirus (PV) plays an important role in the global program for eradication of wild PV. The bag-mediated filtration system (BMFS) was first developed in 2014 and enhances PV surveillance when compared to the two-phase grab method currently recommended by the World Health Organization (WHO). In this study, the BMFS design was improved and tested for its usability in wastewater and wastewater-impacted surface waters in Nairobi, Kenya. Modifications made to the BMFS included the size, color, and shape of the collection bags, the filter housing used, and the device used to elute the samples from the filters. The modified BMFS concentrated 3-10 L down to 10 mL, which resulted in an effective volume assayed (900-3000 mL) that was 6-20 times greater than the effective volume assayed for samples processed by the WHO algorithm (150 mL). The system developed allows for sampling and in-field virus concentration, followed by transportation of the filter for further analysis with simpler logistics than the current methods. This may ultimately reduce the likelihood of false-negative samples by increasing the effective volume assayed compared to samples processed by the WHO algorithm, making the BMFS a valuable sampling system for wastewater and wastewater-impacted surface waters.

Prevalence and genetic diversity of rotavirus infection in children with acute gastroenteritis in a hospital setting, Nairobi Kenya in post vaccination era: a cross-sectional study.

INTRODUCTION: Rotavirus is the leading cause of severe diarrhoea among infants and young children. Each year more than 611 000 children die from rotavirus gastroenteritis, and two million are hospitalized, worldwide. In Kenya, the impact of recent rotavirus vaccinations on morbidities has not been estimated. The study aimed at determining the prevalence and identity of rotavirus strains isolated from rotavirus-associated diarrhoea in vaccinated children presenting with acute gastroenteritis. METHODS: Two hundred and ninety eight specimen from children presented at Gertrude Childrens' Hospital from January to June 2012 were tested by EIA (Enzyme-linked Immunosorbent Assay) for rotavirus antigens. Molecular characterization was conducted on rotavirus-positive specimens. Extracted viral RNA was separated by polyacrylamide gel electrophoresis (PAGE) and the specific rotavirus VP4 (P-types) and VP7 (G-types) determined. RESULTS: The prevalence rate of rotavirus was 31.5% (94/298). Of the rotavirus dsRNA, 57 (60.1%) gave visible RNA profiles, 38 (40.4%) assigned long electropherotypes while 19 (20.2%) were short electropherotypes. The strains among the vaccinated were G3P [4], G12P [6], G3P [6], G9P [4], G mixed G9/3P [4] and G1/3P [4]. Specifically, the G genotypes were G9/3 (5.3%), G9 (4.3%), G3 (4.3%), G12 (2.1%) and mixed G1/3 (1.1%). The P genotypes detected were P [4] (5.3%) and P [6] (5.3%). CONCLUSION: The present study demonstrates diversity in circulating genotypes with emergence of genotypes G3, G9, G12 and mixed genotypes G9/3 and recommends that vaccines should be formulated with a broad range of strains to include G9 and G12.