Publications by authors named "Nyangao J"

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.

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  • The study examines rotavirus A's genetic characteristics in children with gastroenteritis at Kericho County Referral Hospital, with a focus on regions highly affected by mortality due to the virus, particularly in sub-Saharan Africa and South Asia.
  • A total of 200 stool samples were analyzed, revealing a rotavirus prevalence of 11.5%, predominantly among children with guardians who had secondary education and those aged 21-30 months.
  • The G3 genotype was most common among the rotavirus strains identified, highlighting the need for ongoing surveillance and potential updates to vaccines to include emerging strains.
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  • Human G4P[6] rotavirus strains have been found in patients with diarrhea worldwide, but only one strain from Africa has been fully sequenced so far.
  • In this study, researchers characterized a unique G4P[6] strain from a Kenyan child, identifying its genome as having significant porcine origins due to interspecies transmission.
  • This is the first complete genome analysis of a human G4P[6] strain in East Africa, highlighting the genetic diversity and origins of these rotaviruses in the region.
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  • Rotaviruses are a major cause of gastroenteritis in young children, and a monovalent vaccine (Rotarix) was introduced in Kenya in 2014 to combat this issue, but no studies have been done to analyze the circulating genotypes post-vaccination.* -
  • This study collected stool samples from vaccinated children under 5 with diarrhea in Nairobi County to determine the prevalence and types of rotavirus genotypes since the vaccine's introduction.* -
  • Results showed a shift in rotavirus strains; while G1P[8] dominance decreased, G2P[4] and G9P[8] genotypes increased, indicating a change in strain diversity and underscoring the need for ongoing
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Aims: This study compared the bag-mediated filtration system (BMFS) and standard WHO two-phase separation methods for poliovirus (PV) environmental surveillance, examined factors impacting PV detection and monitored Sabin-like (SL) PV type 2 presence with withdrawal of oral polio vaccine type 2 (OPV2) in April 2016.

Methods And Results: Environmental samples were collected in Nairobi, Kenya (Sept 2015-Feb 2017), concentrated via BMFS and two-phase separation methods, then assayed using the WHO PV isolation algorithm and intratypic differentiation diagnostic screening kit. SL1, SL2 and SL3 were detected at higher rates in BMFS than two-phase samples (P < 0·05).

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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.

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  • - The bag-mediated filtration system (BMFS) was created to improve the environmental surveillance of poliovirus (PV) and complements traditional methods focused on acute flaccid paralysis to help with PV eradication efforts in Nairobi, Kenya, from April to September 2015.
  • - During the study, environmental samples were collected and processed using two methods: BMFS (which filtered over 3 liters) and a grab sample method (collecting 1 liter). The samples were then analyzed for poliovirus presence using various techniques, including rRT-PCR.
  • - Results showed that BMFS detected Sabin polioviruses more frequently than the other method, especially Sabin-like PV type 3, indicating its effectiveness for environmental monitoring, while no
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  • This study highlights the importance of enteric virus surveillance due to their low infectious doses and long environmental persistence, using a novel bag-mediated filtration system (BMFS).
  • The researchers found that enteroviruses and PMMoV were present in 100% of wastewater samples collected from various sites in Kenya, while other viruses like adenovirus and norovirus were detected in most samples.
  • The consistent presence of these viruses indicates their potential use as contamination indicators and emphasizes the need for effective monitoring of water sources worldwide.
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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.

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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.

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Introduction: Rotavirus is a leading cause of morbidity and mortality among children under five years worldwide. This study aimed to characterize the circulating genotypes of rotavirus and to determine risk factors of rotavirus infection in North Eastern, Kenya before the introduction of rotavirus vaccines.

Methods: we conducted a cross sectional study among children < 5 years old hospitalized for acute gastroenteritis at the study hospital.

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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.

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A monovalent rotavirus vaccine (RV1) was introduced into the National Immunization Program in Kenya in July 2014. We examined the impact of the vaccine on hospitalization for all-cause acute gastroenteritis (AGE) and rotavirus-specific AGE and strain distribution at a large referral hospital which serves a predominantly peri-urban population in Central Kenya. Data on rotavirus AGE and strain distribution were derived from ongoing hospital-based AGE surveillance.

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Background: Gastroenteritis is a public health concern due to high morbidity and mortality among children. Rotaviruses are the leading etiological agents of severe gastroenteritis in children and accounts for more than half a million deaths per year in Africa. The study aimed at investigating the rotavirus genotypes that were circulating in children aged 5 years and below in and around Mukuru slums in Nairobi County Kenya.

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  • - Environmental surveillance of poliovirus (PV) is crucial for global eradication efforts, with the bag-mediated filtration system (BMFS) enhancing effectiveness compared to the WHO's two-phase grab method.
  • - The study improved the BMFS for use in wastewater and surface waters in Nairobi by modifying aspects such as bag size and filter design to increase efficiency.
  • - The enhanced BMFS can concentrate larger volumes of water (3-10 L down to 10 mL), resulting in a 6-20 times greater effective volume assayed than the WHO method, potentially reducing false-negative results and simplifying logistics for virus detection.
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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.

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This cross-sectional descriptive study aimed to investigate the incidence of rotavirus and enteric bacterial infections among children up to 5 years old with diarrhea living in suburban and rural areas of Kenya. Between August 2011 and December 2013, a total of 1,060 diarrheal fecal specimens were obtained from 722 children at Kiambu County Hospital (KCH), located in a suburban area, and from 338 children from Mbita District Hospital (MDH), located in a rural part of western Kenya. Of the 1,060 isolates, group A rotavirus was detected in 29.

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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.

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Background: Rotavirus remains a leading cause of acute gastroenteritis in children worldwide with an estimated 2000 deaths each day in developing countries. Due to HIV/AIDS scourge in Kenya, it is possible that rotavirus-related gastroenteritis has been aggravated in adults. The Global Alliance for Immunizations has ranked rotavirus infection a priority for vaccine, and, to ensure its success, there is a need to document the local strain(s) circulating in different regions.

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G12 rotaviruses are globally emerging rotavirus strains causing severe childhood diarrhea. However, the whole genomes of only a few G12 strains have been fully sequenced and analyzed, of which only one G12P[4] and one G12P[6] are from Africa. In this study, we sequenced and characterized the complete genomes of three G12 strains (RVA/Human-tc/KEN/KDH633/2010/G12P[6], RVA/Human-tc/KEN/KDH651/2010/G12P[8], and RVA/Human-tc/KEN/KDH684/2010/G12P[6]) identified in three stool specimens from children with acute diarrhea in Kenya, Africa.

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Group A rotaviruses (RV-A) are the leading cause of viral gastroenteritis in children worldwide and genotype G9P[8] is one of the five most common genotypes detected in humans. In order to gain insight into the degree of genetic variability of G9P[8] strains circulating in Cameroon, stool samples were collected during the 1999-2000 rotavirus season in two different geographic regions in Cameroon (Southwest and Western Regions). By RT-PCR, 15 G9P[8] strains (15/89=16.

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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.

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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.

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We report here the full genomic analysis of a simian SA11-like G3P[2] group A rotavirus (GAR) strain, B10, isolated from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the VP7-VP4-VP2-VP3-NSP1-NSP2-NSP3-NSP5 genes of strain B10 exhibited maximum genetic relatedness to those of the different isolates of simian strain SA11, and were assigned to the G3-P[2]-C5-M5-A5-N5-T5-H5 genotypes, respectively. On the other hand, the VP1, VP6 and NSP4 genes of strain B10 did not belong to any of the established GAR genotypes, and therefore, were assigned to new genotype numbers R8, I16 and E13, respectively, by the Rotavirus Classification Working Group.

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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.

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