Rotavirus genetic diversity, disease association, and temporal change in hospitalized rural Kenyan children

Deployment of Rotavirus Vaccine in Western Kenya Coincides with a Reduction in All-Cause Child Mortality: A Retrospective Cohort Study

Rotavirus is an important cause of fatal pediatric diarrhea worldwide. Many national immunization programs began adding rotavirus vaccine following a 2009 World Health Organization recommendation. Kenya added rotavirus vaccine to their immunization program at the end of 2014. From a cohort of 38,463 children in the Kisumu health and demographic surveillance site in western Kenya, we assessed how the implementation of the rotavirus vaccine affected mortality in children under 3 years of age. Following its introduction in late 2014, the span of rotavirus vaccine coverage for children increased to 75% by 2017. Receiving the rotavirus vaccine was associated with a 44% reduction in all-cause child mortality (95% confidence interval = 28-68%, p < 0.0001), but not diarrhea-specific mortality (p = 0.401). All-cause child mortality declined 2% per month following the implementation of the rotavirus vaccine (p = 0.002) among both vaccinated and unvaccinated children, but diarrhea-specific mortality was not associated with the implementation of the rotavirus vaccine independent of individual vaccine status (p = 0.125). The incidence of acute diarrhea decreased over the study period, and the introduction of the rotavirus vaccine was not associated with population-wide trends (p = 0.452). The receipt of the rotavirus vaccine was associated with a 34% reduction in the incidence of diarrhea (95% confidence interval = 24-43% reduction). These results suggest that rotavirus vaccine may have had an impact on all-cause child mortality. The analyses of diarrhea-specific mortality were limited by relatively few deaths (n = 57), as others have found a strong reduction in diarrhea-specific mortality. Selection bias may have played a part in these results-children receiving rotavirus vaccine were more likely to be fully immunized than children not receiving the rotavirus vaccine.

Factors associated with dehydrating rotavirus diarrhea in children under five in Bangladesh: An urban-rural comparison

Introduction

Rotavirus is the leading cause of dehydrating diarrhea in young children worldwide. This study aimed to identify the factors associated with dehydrating rotavirus diarrhea in children under five years of age in urban and rural Bangladesh.

Methods

The study analyzed data from 7,758 children under five who presented with rotavirus diarrhea to Dhaka (urban) and Matlab (rural) hospital of icddr,b during 2009–2018, and were enrolled in the Diarrheal Disease Surveillance System. Cases were defined as children having rotavirus isolated in stool specimens presented with dehydrating diarrhea. Controls were children infected with rotavirus have no dehydration. Multivariable logistic regression models were built to identify the factors associated with dehydrating diarrhea.

Results

Among the rotavirus-infected children, 1,784 (34%) in Dhaka and 160 (6%) in Matlab had diarrhea with some or severe dehydration. The female children and age group 24–59 months age was found to be at higher risk of dehydration compared to 6–11 months age. In the multivariable logistic regression model, maternal illiteracy, vomiting, the onset of diarrhea less than 24 hours prior to presenting to the hospital, monsoon months, stunting, and wasting were significantly associated with dehydrating rotavirus diarrhea among children aged 0–59 months in Dhaka. In Matlab, monthly income, duration less than 24 hours prior to attending the hospital, and wasting had an independent significant association with dehydrating rotavirus diarrhea episodes.

Conclusions

Considering factors diversity, educating parents and proper counselling by health care personnel during diarrhea, could lessen the severity of dehydration and the number of hospital visits later on by eliminating the modifiable risk factors among the children, which needs further studies.

Impact of integrated water, sanitation, hygiene, health and nutritional interventions on diarrhoea disease epidemiology and microbial quality of water in a resource-constrained setting in Kenya: A controlled intervention study

Objectives

We assessed the impact of water, hygiene and sanitation (WASH), maternal, new‐born and child health (MNCH), nutrition and early childhood development (ECD) on diarrhoea and microbial quality of water in a resource‐constrained rural setting in Kenya.

Methods

Through a controlled intervention study, we tested faecal and water samples collected from both the intervention and control sites before and after the interventions using microbiological, immunological and molecular assays to determine the prevalence of diarrhoeagenic agents and microbial quality of water. Data from the hospital registers were used to estimate all‐cause diarrhoea prevalence.

Results

After the interventions, we observed a 58.2% (95% CI: 39.4–75.3) decline in all‐cause diarrhoea in the intervention site versus a 22.2% (95% CI: 5.9–49.4) reduction of the same in the control site. Besides rotavirus and pathogenic Escherichia coli, the rate of isolation of other diarrhoea‐causing bacteria declined substantially in the intervention site. The microbial quality of community and household water improved considerably in both the intervention (81.9%; 95% CI: 74.5%–87.8%) and control (72.5%; 95% CI: 64.2%–80.5%) sites with the relative improvements in the intervention site being slightly larger.

Conclusions

The integrated WASH, MNCH, nutrition and ECD interventions resulted in notable decline in all‐cause diarrhoea and improvements in water quality in the rural resource‐limited population in Kenya. This indicates a direct public health impact of the interventions and provides early evidence for public health policy makers to support the sustained implementation of these interventions.

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.

Genetic characterization of group-A rotaviruses among children in eastern India during 2014-2016: Phylodynamics of co-circulating genotypes

BACKGROUND

Group-A human rotaviruses (GARV) are among the major cause of childhood diarrhea worldwide. In lieu of monitoring the circulatory GARV strains and underscoring the burden of GARV related hospitalization, a systematic surveillance was conducted in three hospitals of eastern India. In this hospital-based diarrheal disease surveillance (2014-2016), GARV was the most common cause of acute infantile gastroenteritis. The strains were genotyped and characterized to understand their prevalence and phylodynamics prior to the introduction of vaccine in eastern India.

MATERIALS AND METHODS

A total of 3652 stool samples were screened from children (≤5 years) hospitalized with acute diarrhea during 2014-2016. Initial screening for VP6 antigen was done by ELISA. GARV positive samples were genotyped by multiplex semi-nested PCR and DNA sequencing and phylogenetic analyses were based on the capsid proteins VP4 and VP7.

RESULTS

Of 3652 samples, 1817 (49.8%) were GARV positive. G1, G2, G3 and G9 in conjunction with P[4], P[6]and P[8]genotypes were seen to co-circulate in the population. A sharp deflection from G1 to G3 occurred since 2016; upsurge of G9 strains was seen in alternate years, whereas G2 strains had a low frequency. All the circulating genotypes depicted a low phylogenetic relatedness to the vaccine strains. Differences in antigenic epitopes of VP4 and VP7 proteins in local strains were seen when compared to the vaccine strains. A significant difference in the degree of dehydration, duration of mean hospital stay and frequency of vomiting/24 h between GARV positive and negative children was evident.

CONCLUSION

The study provides a relevant set of base-line data on high burden of rotaviral gastroenteritis and the varied genotypic diversity among children prior to the introduction of GARV vaccine in this endemic region. Continuous monitoring during post-vaccination era will be required to assess the impact of vaccination in this region.

Molecular characterization of rotavirus group A strains circulating prior to vaccine introduction in rural coastal Kenya, 2002-2013

Background: Kenya introduced the monovalent Rotarix® rotavirus group A (RVA) vaccine nationally in mid-2014.  Long-term surveillance data is important prior to wide-scale vaccine use to assess the impact on disease and to investigate the occurrence of heterotypic strains arising through immune selection. This report presents baseline data on RVA genotype circulation patterns and intra-genotype genetic diversity over a 7-year period in the pre-vaccine era in Kilifi, Kenya, from 2002 to 2004 and from 2010 to 2013.

Methods: A total of 745 RVA strains identified in children admitted with acute gastroenteritis to a referral hospital in Coastal Kenya, were sequenced using the di-deoxy sequencing method in the VP4 and VP7 genomic segments (encoding P and G proteins, respectively). Sequencing successfully generated 569 (76%) and 572 (77%) consensus sequences for the VP4 and VP7 genes respectively. G and P genotypes were determined by use of BLAST and the online RotaC v2 RVA classification tool.

Results: The most common GP combination was G1P[8] (51%), similar to the Rotarix® strain, followed by G9P[8] (15%) , G8P[4] (14%) and G2P[4] (5%).  Unusual GP combinations—G1P[4], G2P[8], G3P[4,6], G8P[8,14], and G12P[4,6,8]—were observed at frequencies of <5%. Phylogenetic analysis showed that the infections were caused by both locally persistent strains as evidenced by divergence of local strains occurring over multiple seasons from the global ones, and newly introduced strains, which were closely related to global strains. The circulating RVA diversity showed temporal fluctuations both season by season and over the longer-term. None of the unusual strains increased in frequency over the observation period.  

Conclusions: The circulating RVA diversity showed temporal fluctuations with several unusual strains recorded, which rarely caused major outbreaks.  These data will be useful in interpreting genotype patterns observed in the region during the vaccine era.

Rates of hospitalization and death for all-cause and rotavirus acute gastroenteritis before rotavirus vaccine introduction in Kenya, 2010-2013

Background

Rotavirus vaccine was introduced in Kenya immunization program in July 2014. Pre-vaccine disease burden estimates are important for assessing vaccine impact.

Methods

Children with acute gastroenteritis (AGE) (≥3 loose stools and/or ≥ 1 episode of unexplained vomiting followed by loose stool within a 24-h period), hospitalized in Siaya County Referral Hospital (SCRH) from January 2010 through December 2013 were enrolled. Stool specimens were tested for rotavirus (RV) using an enzyme immunoassay (EIA). Hospitalization rates were calculated using person-years of observation (PYO) from the Health Demographic Surveillance System (HDSS) as a denominator, while adjusting for healthcare utilization at household level and proportion of stool specimen collected from patients who met the case definition at the surveillance hospital. Mortality rates were calculated using PYO as the denominator and number of deaths estimated using total deaths in the HDSS, proportion of deaths attributed to diarrhoea by verbal autopsy (VA) and percent positive for rotavirus AGE (RVAGE) hospitalizations.

Results

Of 7760 all-cause hospitalizations among children < 5 years of age, 3793 (49%) were included in the analysis. Of these, 21% (805) had AGE; RV was detected in 143 (26%) of 541 stools tested. Among children < 5 years, the estimated hospitalization rates per 100,000 PYO for AGE and RVAGE were 2413 and 429, respectively. Mortality rate associated with AGE and RVAGE were 176 and 45 per 100,000 PYO, respectively.

Conclusion

AGE and RVAGE caused substantial health care burden (hospitalizations and deaths) before rotavirus vaccine introduction in Kenya.

Molecular characterization of rotavirus group A strains circulating prior to vaccine introduction in rural coastal Kenya, 2002-2013

Background: Kenya introduced the monovalent Rotarix® rotavirus group A (RVA) vaccine nationally in mid-2014.  Long-term surveillance data is important prior to wide-scale vaccine use to assess the impact on disease and to investigate the occurrence of heterotypic strains arising through immune selection. This report presents baseline data on RVA genotype circulation patterns and intra-genotype genetic diversity over a 7-year period in the pre-vaccine era in Kilifi, Kenya, from 2002 to 2004 and from 2010 to 2013. Methods: A total of 745 RVA strains identified in children admitted with acute gastroenteritis to a referral hospital in Coastal Kenya, were sequenced using the di-deoxy sequencing method in the VP4 and VP7 genomic segments (encoding P and G proteins, respectively). Sequencing successfully generated 569 (76%) and 572 (77%) consensus sequences for the VP4 and VP7 genes respectively. G and P genotypes were determined by use of BLAST and the online RotaC v2 RVA classification tool. Results: The most common GP combination was G1P[8] (51%), similar to the Rotarix® strain, followed by G9P[8] (15%) , G8P[4] (14%) and G2P[4] (5%).  Unusual GP combinations—G1P[4], G2P[8], G3P[4,6], G8P[8,14], and G12P[4,6,8]—were observed at frequencies of <5%. Phylogenetic analysis showed that the infections were caused by both locally persistent strains as evidenced by divergence of local strains occurring over multiple seasons from the global ones, and newly introduced strains, which were closely related to global strains. The circulating RVA diversity showed temporal fluctuations both season by season and over the longer-term. None of the unusual strains increased in frequency over the observation period.   Conclusions: The circulating RVA diversity showed temporal fluctuations with several unusual strains recorded, which rarely caused major outbreaks.  These data will be useful in interpreting genotype patterns observed in the region during the vaccine era.

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 and associated risk factors of rotavirus infection among children < 5 yrs hospitalized for acute gastroenteritis in North Eastern, Kenya, 2012

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. Rotavirus was detected in stool specimens and further characterized using PAGE and RT-PCR. Socio-demographic and risk factor information was collected using a standard questionnaire.

RESULTS

we enrolled 237 children into the study hospitalized with acute gastroenteritis. Of these, 41 (17%) tested positive for group A rotavirus in stool specimens. Age < 2 years, unboiled tap water, underweight and low birth weight were identified as independent risk factors of rotavirus infection. Majority 8 (57%) of the detected rotavirus RNA profiles were long electropherotypes. G3, G9 and P4 were the predominant genotypes identified.

CONCLUSION

Rotavirus is an important aetiology of acute gastroenteritis among children under five years in this region. Risk factors common in other regions and rotavirus vaccine preventable genotypes are responsible for infection. We recommend the introduction of rotavirus vaccines, coupled with good infant nutrition, safe water supply and maternal hygienic practices during infant feeding.

Genotype distribution of Group A rotavirus from southern India, 2005-2016

Diarrheal disease due to Group A rotaviruses remain a leading cause of mortality and morbidity in the less developed parts of the world. India has started a phased roll out of rotavirus vaccine in the national immunization program. This analysis summarizes the rotavirus genotype strain distribution pre-vaccine introduction in Vellore, India from December 2005 to June 2016. Rotavirus was responsible for 32% of all diarrheal admission to the hospital. G2P[4] was the predominant strain in the initial years and was gradually replaced by G1P[8]. The emergence of G9P[4] replacing G9P[8], and the detection of G12 strains over several years were documented. There was no clear seasonality of disease. These data form the baseline to monitor genotype distribution post-vaccine introduction in Tamil Nadu.

Impact of rotavirus vaccination on rotavirus and all-cause gastroenteritis in peri-urban Kenyan children

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. Hospital administrative data were used to compare trends in all-cause AGE. Pre-vaccine (July 2009-June 2014) and post-vaccine (July 2014-June 2016) periods were compared for changes in hospitalization for all-cause AGE and rotavirus AGE and strain distribution. Following the vaccine introduction, the proportion of children aged <5years hospitalized for rotavirus declined by 30% (95% CI: 19-45%) in the first year and 64% (95% CI: 49-77%) in the second year. Reductions in rotavirus positivity were most pronounced among the vaccine-eligible group (<12months) in the first year post-vaccination at 42% (95% CI: 28-56%). Greater reductions of 67% (95% CI: 51-79%) were seen in the second year in the 12-23months age group. Similarly, hospitalizations for all-cause AGE among children <5years of age decreased by 31% (95% CI: 24-40%) in the first year and 58% (95% CI: 49-67%) in the second year of vaccine introduction. Seasonal peaks of rotavirus and all-cause AGE were reduced substantially. There was an increased detection of G2P[4], G3P[6] and G3P[8], which coincided temporally with the timing of the vaccine introduction. Thus, introducing the rotavirus vaccine into the routine immunization program in Kenya has resulted in a notable decline in rotavirus and all-cause AGE hospitalizations in Central Kenya. This provides early evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunizations.

Human P[6] Rotaviruses From Sub-Saharan Africa and Southeast Asia Are Closely Related to Those of Human P[4] and P[8] Rotaviruses Circulating Worldwide

BACKGROUND

P[6] rotaviruses have been circulating with a high prevalence in African and, to a more limited extent, Asian countries, but they have not been highly prevalent in other parts of the world.

METHODS

To investigate the genomic relationship between African and Asian human P[6] rotaviruses and P[4] and P[8] rotaviruses circulating worldwide, we sequenced 39 P[6] strains, collected in Ghana, Mali, Kenya and Bangladesh, providing the largest data set of P[6] rotavirus genomes isolated in low-income countries or anywhere else in the world that has been published thus far.

RESULTS

Overall, the data indicate that the genetic backbone of human P[6] strains from the low-income countries are similar to those of P[4] or P[8] strains circulating worldwide.

CONCLUSIONS

The observation that gene segment 4 is the main differentiator between human P[6] and non-P[6] strains suggests that the VP4 spike protein is most likely one of the main reasons preventing the rapid spread of P[6] strains to the rest of the world despite multiple introductions. These observations reinforce previous findings about the receptor specificity of P[6] rotavirus strains.

Predominance of rotavirus G1[P8] genotype among under-five children with gastroenteritis in Mwanza, Tanzania

We analyzed stool samples from underfives with gastroenteritis for rotavirus infection between January 2010 and June 2011. A total of 393 stool specimens were examined for rotavirus infection using enzyme-linked immunosorbent assay (ELISA). Hundred selected positive specimens were genotyped using multiplex polymerase chain reaction. Out of 393 underfives, 194 (49.4%) had rotavirus infection, with 96.9% of infected underfives being <2 years. Underfives infected with rotavirus had prolonged hospital stay than those without rotavirus infection (P = 0.0001). G1 was the most predominant G type (59%) followed by G8 (13%) while P[8] was the most predominant P type (25%). In single-type infection, common G-P combinations were G1P[8] (24%) and G1P[6] (17%). Common mixed infections were G1/G8 (16%) and P4/P8 (13%). G1 genotype is common among underfives with gastroenteritis in Mwanza. Diversity of genotypes causing gastroenteritis in Mwanza necessitates a continuous surveillance after the introduction of RotaRix® vaccine.

Rotavirus surveillance in Kisangani, the Democratic Republic of the Congo, reveals a high number of unusual genotypes and gene segments of animal origin in non-vaccinated symptomatic children

Group A rotavirus (RVA) infections form a major public health problem, especially in low-income countries like the Democratic Republic of the Congo (COD). However, limited data on RVA diversity is available from sub-Saharan Africa in general and the COD in particular. Therefore, the first aim of this study was to determine the genetic diversity of 99 RVAs detected during 2007–2010 in Kisangani, COD. The predominant G-type was G1 (39%) and the most predominant P-type was P[6] (53%). A total of eight different G/P-combinations were found: G1P[8] (28%), G8P[6] (26%), G2P[4] (14%), G12P[6] (13%), G1P[6] (11%), G9P[8] (4%), G4P[6] (2%) and G8P[4] (1%). The second aim of this study was to gain insight into the diversity of P[6] RVA strains in the COD. Therefore, we selected five P[6] RVA strains in combination with the G1, G4, G8 (2x) or G12 genotype for complete genome analysis. Complete genome analysis showed that the genetic background of the G1P[6] and G12P[6] strains was entirely composed of genotype 1 (Wa-like), while the segments of the two G8P[6] strains were identified as genotype 2 (DS-1-like). Interestingly, all four strains possessed a NSP4 gene of animal origin. The analyzed G4P[6] RVA strain was found to possess the unusual G4-P[6]-I1-R1-C1-M1-A1-N1-T7-E1-H1 constellation. Although the majority of its genes (if not all), were presumably of porcine origin, this strain was able to cause gastro-enteritis in humans. The high prevalence of unusual RVA strains in the COD highlights the need for continued surveillance of RVA diversity in the COD. These results also underline the importance of complete genetic characterization of RVA strains and indicate that reassortments and interspecies transmission among human and animal RVAs strains occur regularly. Based on these data, RVA vaccines will be challenged with a wide variety of different RVA strain types in the COD.

Detection and characterisation of bovine rotavirus in Ireland from 2006-2008

Background

Worldwide, Group A bovine rotavirus (RVA boRV) is one of the main causes of neonatal calf diarrhoea. Currently, limited epidemiological and sequence data exists on the RVA disease in bovines in Southern Ireland only. The aim of the study was to generate epidemiological and sequence data of RVA boRV distributed over a wide geographical area in Ireland.

Findings

272 stool samples were obtained from symptomatic calves and analysed to identify the prevalent G and P genotypes. Viral type combinations including G6P[5], G6P[11] and G10P[11] genotype were the most frequently identified. The G6P[5] combination was predominant throughtout the study, accounting for 70% (n = 191). Sequence analysis of the VP7 gene revealed that Irish G6 strains fell within Lineage IV, similiar to previous reports in Ireland.

Conclusion

The detection of unusual G and P combinations may have an impact on rotavirus control programmes and current vaccines may need to incorporate new strains, as the current vaccine available may not offer protection against all of these circulating types.

Hospital-based surveillance for rotavirus gastroenteritis in children younger than 5 years of age in Ethiopia: 2007-2012

BACKGROUND

Rotavirus surveillance was initiated in Ethiopia to estimate the burden of rotavirus gastroenteritis in children <5 years of age, to generate data to assist the policy-making process for new vaccine introduction and to monitor impact of vaccination on disease burden after introduction.

METHODS

Sentinel surveillance was conducted at 3 hospitals in Addis Ababa, Ethiopia using a standardized WHO surveillance protocol from August 2007 to March 2012. Children <5 years of age, hospitalized for the primary reason of treatment for acute gastroenteritis, were enrolled, stool samples were collected and tested for group A rotavirus using an enzyme immunoassay. Confirmed positive specimens were further characterized by rotavirus genotyping.

RESULTS

A total of 1841 children were enrolled and 21% were rotavirus positive. Children 6-12 months of age had the highest proportion of rotavirus (36%) followed by children <6 months of age (23%). There was no significant difference between sexes. Significant differences in clinical characteristics, such as vomiting, vomiting episodes, cases with vomiting and diarrhea among rotavirus positive cases, were observed. Rotavirus circulated year round with peak prevalence from October through January. The most prevalent detected genotypes were G1P[8] (20%), G12P[8] (17%) and G3P[6] (15%), respectively.

CONCLUSIONS

Rotavirus infection is common in Ethiopian children. A safe and effective intervention against the infection is needed to prevent severity of the disease. Rotavirus vaccine introduction is planned before the end of 2013. The established surveillance system and the data generated can be used to monitor the impact of rotavirus vaccination program on severe disease.

High genotypic diversity among rotavirus strains infecting Gambian children

BACKGROUND

Rotavirus is the leading cause of diarrhea in children <5 years of age. In light of the implementation of rotavirus vaccines of limited valency, it is important to characterize the genotypic diversity of circulating rotavirus in sub-Saharan Africa.

METHODS

We collected stool samples from children 0-59 months of age who presented at the health centres as cases with moderate-to-severe diarrhea in the Upper River Region of The Gambia. Stool samples were also collected from age, sex and area-matched healthy controls. All stool samples were assayed for rotavirus antigens by enzyme-linked immunosorbent assay and genotyping was done using reverse transcriptase polymerase chain reaction.

RESULTS

We enrolled 1029 cases and 1569 controls during the 3-year study period (2008-2010). The detection rate of rotavirus among the cases was 20% (204/1029) and 3% (42/1569) among controls. At least 18 genotypes were found and the predominant genotypes were G2P[6] (28%), G1P[8] (26%) and G1P[10] (10%). The rare identified genotypes (<1%) were G2P[14], G8P[6], G9P[6] and G4P[10]. There was also a strong positive association between rotavirus infection and the dry season (odds ratio: 9.83, 95% confidence interval: 6.18-15.63, P < 0.001). A significant increase in the odds of rotavirus and G1P[8] detection with the use of untreated water and the presence of cats, rodents and cows in the child's residence was also found.

CONCLUSION

This study provides important baseline data for the genotypes circulating before vaccine implementation. The wide diversity of genotypes circulating in The Gambia implies the need for vigilant effectiveness surveillance following the implementation of RotaTeq in August 2013.

Epidemiology of rotavirus diarrhea and diversity of rotavirus strains among children less than 5 years of age with acute gastroenteritis in Mauritius: June 2008 to December 2010

BACKGROUND

Rotavirus is an important etiologic agent of diarrhea worldwide and ongoing surveillance is essential to monitor strain diversity. To describe the epidemiology of rotavirus disease and circulating rotavirus strains in Mauritius, surveillance for rotavirus diarrhea was conducted at 2 regional hospitals from June 2008 through December 2010.

METHODS

A total of 787 fecal samples from children <5 years of age admitted to the pediatric ward with acute gastroenteritis was collected within 48 hours of hospitalization and analyzed for group A rotavirus. A subset of rotavirus-positive samples was subjected to polyacrylamide gel electrophoresis and VP4 and VP7 genotyping.

RESULTS

Rotavirus was detected in 327 (41.6%) stools. Highest prevalence of rotavirus infection occurred in children <2 years of age, predominately between 12 and 23 months. Three seasonal peaks were observed during the study period: July to October 2008, October to December 2009 and July to October 2010. Polyacrylamide gel electrophoresis analysis of 116 positive samples yielded only long electropherotypes. The predominant circulating strain was G3P[8] (89%) from June through December 2008, G4P[8] (76%) from January through December 2009 and G1P[8] (90%) from January through December 2010.

CONCLUSIONS

The diversity of rotavirus strains detected in this study highlights the need for continuous surveillance and data generated can be used to advocate for rotavirus vaccine introduction.

Rotavirus G and P types circulating in the eastern region of Kenya: predominance of G9 and emergence of G12 genotypes

BACKGROUND

The World Health Organization has recommended that rotavirus (RV) vaccines be included in all national immunization programs as part of a strategy to control RV-associated diarrheal diseases. Hospital-based surveillance of RV infection is therefore crucial in monitoring the impact pre- and post-vaccine introduction and also to document changes in genotype distribution. This study sought to determine the RV genotypes circulating in the eastern region of Kenya before introduction of the RV vaccine.

METHODS

During September 2009 to August 2011, 500 stool samples were collected from children <5 years of age admitted for acute diarrhea in hospitals in the eastern region of Kenya and analyzed for the presence of group A RV using an enzyme immunoassay. G and P genotypes were determined using hemi-nested reverse transcriptase polymerase chain reaction.

RESULTS

One hundred and eighty nine out of 500 (38%) samples analyzed were positive for rotavirus. The following G types were detected: G9 (50.9%), G1 (26.8%), G8 (12.1%), G12 (3.1%), G2 (0.6%), mixed G (1.3%) and 5.1% were G nontypeable. P types detected included: P[8] (63.7%), P[4] (12.1%), P[6] (4.5%), mixed P (7.6%) and 12.1% were P nontypeable. The most dominant strain was G9P[8] (35%), followed by G1P[8] (26.8%), G8P[4] (9.6%), G12P[6] (2.5%), G9P[6] (1.9%), G9P[4] (1.3%), G8P[8] (1.3%), and G2P[4] (0.6%).

CONCLUSIONS

The present study demonstrates the recurring changing genotypes of RV circulating in Kenya, with genotypes G9, G1 and G8 being the dominant strains circulating in the eastern region of Kenya between 2009 and 2011. Additionally, G12 genotype was detected for the first time in Kenya.

Rotavirus genotypes associated with childhood severe acute diarrhoea in southern Ghana: a cross-sectional study

Background

Rotavirus immunization has been effective in developed countries where genotype G1P[8] is the predominant rotavirus strain. Knowledge of circulating strains in a population before introduction of rotavirus immunization program will be useful in evaluating the effect of the intervention.

Methods

Rotavirus was identified by enzyme immuno-assay (EIA) on stool specimens of children (age 0 – 59 months) hospitalized with acute gastroenteritis from August 2007 to February 2011 in Accra, Ghana. Rotavirus positive specimens were further characterized by polyacrylamide gel electrophoresis (PAGE) and reverse-transcriptase polymerase chain reaction (RT-PCR).

Results

Of the 2277 acute gastroenteritis hospitalizations 1099 (48.2%) were rotavirus-positive by EIA. Of the 1099 cases 977 (89%) were PAGE positive. All EIA positive specimens were further subjected to RT-PCR and 876 (79.7%) had sufficient material for characterization. Of these 876 cases, 741 (84.6%) were assigned G genotype, 709 (80.9%) P genotype, and 624 (71.2%) both G and P genotypes. We identified 8 G genotypes (G1, G2, G3, G4, G8, G9, G10, G12) and 3 P genotypes (P[4], P[6], P[8]). G1 (50.9%), G2 (18.8%), G3 (12.8%), P[8] (36.1%) and P[6] (30.7%) were the most prevalent. The most prevalent genotype combination was G1P[8] (28%). Mixed G (7.3%) and P (24.2%) genotypes were not uncommon. There was year-by-year and seasonal variations for most genotypes.

Conclusion

There is great diversity of rotavirus strains in children with severe gastroenteritis in southern Ghana. Even though cross-protection with vaccine-induced immunity occurs, continued strain surveillance is recommended after the introduction of rotavirus vaccine in the national immunization program.

A cost effectiveness and capacity analysis for the introduction of universal rotavirus vaccination in Kenya: comparison between Rotarix and RotaTeq vaccines

BACKGROUND

Diarrhoea is an important cause of death in the developing world, and rotavirus is the single most important cause of diarrhoea associated mortality. Two vaccines (Rotarix and RotaTeq) are available to prevent rotavirus disease. This analysis was undertaken to aid the decision in Kenya as to which vaccine to choose when introducing rotavirus vaccination.

METHODS

Cost-effectiveness modelling, using national and sentinel surveillance data, and an impact assessment on the cold chain.

RESULTS

The median estimated incidence of rotavirus disease in Kenya was 3015 outpatient visits, 279 hospitalisations and 65 deaths per 100,000 children under five years of age per year. Cumulated over the first five years of life vaccination was predicted to prevent 34% of the outpatient visits, 31% of the hospitalizations and 42% of the deaths. The estimated prevented costs accumulated over five years totalled US$1,782,761 (direct and indirect costs) with an associated 48,585 DALYs. From a societal perspective Rotarix had a cost-effectiveness ratio of US$142 per DALY (US$5 for the full course of two doses) and RotaTeq US$288 per DALY ($10.5 for the full course of three doses). RotaTeq will have a bigger impact on the cold chain compared to Rotarix.

CONCLUSION

Vaccination against rotavirus disease is cost-effective for Kenya irrespective of the vaccine. Of the two vaccines Rotarix was the preferred choice due to a better cost-effectiveness ratio, the presence of a vaccine vial monitor, the requirement of fewer doses and less storage space, and proven thermo-stability.

New insights into rotavirus vaccines

Rotavirus vaccines have shown to be effective and well tolerated in clinical trials. However it's crucial to point out that immunization occurs in "real-word" conditions different from ideal clinical trial settings. Thus, the impact of rotavirus vaccines in terms of effectiveness and safety needs to be evaluated in real-world conditions. Post-licensure data regarding vaccine impact, effectiveness and safety under routine use are now available and provide a "real-world view". We reviewed published data about the impact of rotavirus vaccines in the post-licensure era.

Burden of rotavirus gastroenteritis and distribution of rotavirus strains in Asia: a systematic review

BACKGROUND

Rotavirus is the leading cause of severe diarrhea in children worldwide. We systematically reviewed the burden of rotavirus gastroenteritis (RVGE) and distribution of rotavirus strains in Asia.

METHODS

We searched MEDLINE, EMBASE and the World Health Organization (WHO) website for the term "rotavirus" and the name of each country. We included studies that were conducted in children between 2000 and 2011 and that examined the epidemiology, health and/or economic burden of RVGE, and G and P-type distribution in Eastern, South East, Southern and Central Asia. Random effects models were used to pool the proportions of RVGE. We also estimated child mortality due to RVGE using the updated WHO and United Nations Children's Fund's mortality estimates in 2008.

RESULTS

The search identified 113 eligible articles. The incidence rates of rotavirus-related hospitalizations in children under 5 years of age ranged from 2.1 to 20.0 cases per 1000 children per year with the highest rates reported in Bangladesh, South Korea, Taiwan, Thailand, and Vietnam. Rotavirus accounted for 37.5% of year-round hospitalized gastroenteritis cases, with higher proportions reported in South East Asia. Rotavirus was associated with approximately 145,000 deaths every year in Asia, with the greatest numbers occurring in India, Pakistan, and Indonesia. The highest annual societal costs of treating RVGE were reported in China (US$365 million), followed by Japan (US$254 million) and India (US$41-72 million). A diversity of rotavirus G and P-types was observed across Asia and the distribution of strains differed by country and year. The most common strains were G1P[8] (23.6%), G2P[4] (11.8%), G3P[8] (18.9%), and G9P[8] (7.4%).

CONCLUSIONS

Rotavirus is associated with substantial hospitalizations and deaths among children and causes large healthcare expenditures throughout Asia. Safe and effective rotavirus vaccines could substantially reduce the burden of disease.

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.