High genotypic diversity among rotavirus strains infecting Gambian children

Associations between livestock keeping, morbidity and nutritional status of children and women in low- and middle-income countries: a systematic review

Livestock keeping can positively influence the nutritional status of populations and households through increased consumption of animal-source foods (ASF) and other indirect pathways, but can also adversely affect health by increasing the risk of diseases. We conducted a systematic review synthesising the current state of knowledge on the associations among livestock keeping, infectious disease and the nutritional status of children under 5 years and women of reproductive age in low- and lower-middle-income countries (LMICs). A comprehensive search of 12 electronic databases and grey literature sources published from 1991 to the end of December 2020 was conducted. Investigations exploring relationships between livestock keeping and risk of infectious disease transmission and nutritional status were selected using pre-defined inclusion criteria. After screening and filtering of 34,402 unique references, 176 references were included in the final synthesis. Most (160/176, 90.1%) of the references included in the final synthesis were from sub-Saharan Africa (SSA) and Asia. About two out of every five (42%) studies reviewed showed that livestock production is associated with improved height-for-age Z scores (HAZ) and weight-for-length/height Z scores (WHZ), while close to a third (30.7%) with improved weight-for-age Z scores (WAZ). Similarly, livestock production showed a positive or neutral relationship with women's nutritional status in almost all the references that reported on the topic. Conversely, four-fifths (66/81, 79.5%) of the references reporting on infection and morbidity outcomes indicated that livestock keeping is linked to a wide range of infectious disease outcomes, which are spread primarily through water, food and insects. In conclusion, in many LMIC settings, livestock production is associated with better nutritional outcomes but also a higher risk of disease transmission or morbidity among women and children.This review was prospectively registered on PROSPERO 2020 [CRD42020193622].

Global Rotavirus and Pneumococcal Conjugate Vaccine Introductions and the Association With Country Disease Surveillance, 2006-2018

BACKGROUND

To inform the introduction of pneumococcal conjugate vaccine (PCV) and rotavirus vaccine, the World Health Organization (WHO) established the Global Invasive Bacterial Vaccine-Preventable Disease Surveillance Network (GISN) and the Global Rotavirus Surveillance Network (GRSN) in 2008. We investigated whether participation in these networks or other surveillance was associated with vaccine introduction.

METHODS

Between 2006 and 2018, among all WHO member states, we used multivariable models adjusting for economic status to assess (1) the association between surveillance for pneumococcal disease or rotavirus disease, including participation in GISN or GRSN and the introduction of the PCV or the rotavirus vaccine, respectively, and (2) the association between the rotavirus disease burden and the rotavirus vaccine introduction among 56 countries participating in GRSN from 2008 to 2018.

RESULTS

Countries that participated in or conducted surveillance for invasive pneumococcal disease or rotavirus disease were 3.5 (95% confidence interval [CI], 1.7-7.1) and 4.2 (95% CI, 2.1-8.6) times more likely to introduce PCV or rotavirus respectively, compared to those without surveillance. Among countries participating in GRSN, there was insufficient evidence to demonstrate an association between countries with higher rotavirus positivity and vaccine introduction.

CONCLUSIONS

Surveillance should be incorporated into advocacy strategies to encourage the introduction of vaccines, with countries benefiting from data from, support for, and coordination of international disease surveillance networks.

A Multiplex PCR/LDR Assay for Viral Agents of Diarrhea with the Capacity to Genotype Rotavirus

Rotavirus and noroviruses are major causes of diarrhea. Variable rotavirus vaccination efficacy in Africa and Asia is multifactorial, including the diversity of circulating strains and viral co-infection. We describe a multiplexed assay that detects and genotypes viruses from stool specimens. It includes a one-step reverse transcriptase PCR reaction, a ligase detection reaction (LDR), then hybridization of fluorescent products to micro-beads. In clinical samples it detects rotavirus, caliciviruses (sapovirus and norovirus), mixed infections, and genotypes or genogroups of rotaviruses and noroviruses, respectively. The assay also has the capacity to detect hepatitis A. The assay was validated on reference isolates and 296 stool specimens from the US and Ghana. The assay was 97% sensitive and 100% specific. The genogroup was concordant in 100% of norovirus, and the genotype in 91% and 89% of rotavirus G- and P-types, respectively. Two rare rotavirus strains, G6P[6] and G6P[8], were detected in stool specimens from Ghana. The high-throughput assay is sensitive, specific, and may be of utility in the epidemiological surveillance for rare and emerging viral strains post-rotavirus vaccine implementation.

Diversity of rotavirus strains circulating in children under five years of age who presented with acute gastroenteritis before and after rotavirus vaccine introduction, University Teaching Hospital, Lusaka, Zambia, 2008-2015

BACKGROUND

Following the introduction of rotavirus vaccine into the routine immunization schedule, the burden of rotavirus disease has significantly reduced in Zambia. Although rotavirus vaccines appear to confer good cross-protection against both vaccine and non-vaccine strains, concerns about strain replacement following vaccine implementation remain. We describe the diversity of the circulating rotavirus strains before and after the Rotarix® vaccine was introduced in Lusaka from January 2012.

METHODS

Under five children were enrolled through active surveillance at University Teaching Hospital using a standardized WHO case investigation form. Stool samples were collected from children who presented with ≥3 loose stool in 24 h and were admitted to the hospital for acute gastroenteritis as a primary illness. Samples were tested for group A rotavirus antigen enzyme-linked immunosorbent assay. Randomly selected rotavirus positive samples were analysed by reverse transcription polymerase chain reaction for G and P genotyping and and Nucleotide sequencing was used to confirm some mixed infections.

RESULTS

A total of 4150 cases were enrolled and stool samples were collected from 4066 (98%) children between 2008 and 2011, before the vaccine was introduced. Rotavirus antigen was detected in 1561/4066 (38%). After vaccine introduction (2012 to 2015), 3168 cases were enrolled, 3092 (98%) samples were collected, and 977/3092 (32%) were positive for rotavirus. The most common G and P genotype combinations before vaccine introduction were G1P[8] (49%) in 2008; G12P[6] (24%) and G9P[8] (22%) in 2009; mixed rotavirus infections (32%) and G9P[8] (20%) in 2010, and G1P[6] (46%), G9P[6] (16%) and mixed infections (20%) in 2011. The predominant strains after vaccine introduction were G1P[8] (25%), G2P[4] (28%) and G2P[6] (23%) in 2012; G2P[4] (36%) and G2P[6] (44%) in 2013; G1P[8] (43%), G2P[4] (9%), and G2P[6] (24%) in 2014, while G2P[4] (54%) and G2P[6] (20%) continued to circulate in 2015.

CONCLUSION

These continual changes in the predominant strains suggest natural secular variation in circulating rotavirus strains post-vaccine introduction. These findings highlight the need for ongoing surveillance to continue monitoring how vaccine use affects strain evolution over a longer period of time and assess any normal seasonal fluctuations of the rotavirus strains.

Impact of pentavalent rotavirus vaccine against severe rotavirus diarrhoea in The Gambia

INTRODUCTION

Rotavirus vaccines protect against the leading cause of severe childhood diarrhoea, and have been introduced in many low-income African countries. The Gambia introducedRotateq® (RV5) into their national immunization program in 2013. We revieweddata from an active rotavirus sentinel surveillancesitefor early evidence of vaccine impact.

METHODS

We compared rotavirus prevalence in diarrhoeal stool in children< 5 years of age admittedat the Edward Francis Small Teaching Hospital sentinel surveillance site before (2013) andafterRV5 introduction (2015-2016) in the Gambia. The rotavirus-percent positive was separately compared for all diarrhoealhospitalizations and for hospitalizations with severe symptoms. Rotavirus prevalence was compared annually for the pre-vaccine year of 2013 with post-vaccine years of 2015 and 2016 using chi-square or Fisher's exact tests and the p-value to establish significant relationship was set at p < 0.05. All analyses were completed in SAS 9.3 (SAS Analytics, North Carolina).

RESULTS

Rotavirus prevalence among all diarrhoeahospitalizations decreased from 22% in 2013 to 11% in 2015 (p = 0.04), while remaining unchanged in 2016 (18%, p = 0.56). For hospitalizations that were clinically severe and/or treated with intravenous fluids (mean of 46 per year), the rotavirus prevalence decreased from 33% in 2013 to 8% in 2015 (p = 0.04), and to 15% in 2016 (p = 0.08). The children with age <1 year accounted for 45% the population infected with rotavirus in both pre and post rotavirus vaccination periods.

CONCLUSIONS

Rotavirus vaccine introduction in the Gambia could be among factors resulting in decreased diarrhea hospitalizations among children at the Edward Francis Small Teaching Hospital, particularly those with severe disease. These results support the continuation of rotavirus vaccine and additional monitoring of rotavirus hospitalization trends in the country.

Molecular Epidemiology of Rotavirus in Children under Five in Africa (2006-2016): A Systematic Review

Group A human rotaviruses (RVA) are the most common causes of severe viral gastroenteritis in infants and young children worldwide. The available vaccines, while effective in Europe and North America have shown a reduced efficacy in Africa. One issue raised is the genetic variability of RVA. The objective of this study was to perform a literature review of molecular epidemiology to determine the prevalence of RVA genotypes circulating in Africa so as to establish a mapping of reliable data on these various genotypes. The search for articles was done from the National Institutes of Health (PUBMED) using three set of keywords. Articles were selected with inclusion criteria such as the date of publication, the age of the children, the sample size and the diagnostic techniques (standardized laboratory techniques). The data were imported into STATA SE version 11 software. Specific prevalence was estimated with Confidence Intervals (CI) of 95%. A total of 326 published studies were initially retrieved, out of which 27 studies were finally selected for the systematic review. The selected studies cover 20 African countries. The most encountered genotypes in Africa during this period were G1 (32.72%), followed by G2 (17.17%), G3 (9.88%), G9 (8.61%) and G12 (7.56%) among the G-types. The most common P-types were P[8] (48.71%) followed by P[6] (22.60%) and P[4] (11.58%) and the G1P[8] combination (22.64%) was the most encountered followed by G2P[4] (8.29%), G9P[8] (6.95%) and G2P[6] (5.00%). North Africa presented the highest prevalence of the P[8] genotype (65.70%). This review provides a comprehensive view of the current circulating rotavirus strains in Africa, which can be important in light of the new rotavirus vaccinations. Indeed, in Africa, the pursuit of national and continental studies for epidemiological surveillance of circulating rotavirus strains is vital for the promotion of future successful vaccines.

Microbiota that affect risk for shigellosis in children in low-income countries

Pathogens in the gastrointestinal tract exist within a vast population of microbes. We examined associations between pathogens and composition of gut microbiota as they relate to Shigella spp./enteroinvasive Escherichia coli infection. We analyzed 3,035 stool specimens (1,735 nondiarrheal and 1,300 moderate-to-severe diarrheal) from the Global Enteric Multicenter Study for 9 enteropathogens. Diarrheal specimens had a higher number of enteropathogens (diarrheal mean 1.4, nondiarrheal mean 0.95; p<0.0001). Rotavirus showed a negative association with Shigella spp. in cases of diarrhea (odds ratio 0.31, 95% CI 0.17-0.55) and had a large combined effect on moderate-to-severe diarrhea (odds ratio 29, 95% CI 3.8-220). In 4 Lactobacillus taxa identified by 16S rRNA gene sequencing, the association between pathogen and disease was decreased, which is consistent with the possibility that Lactobacillus spp. are protective against Shigella spp.-induced diarrhea. Bacterial diversity of gut microbiota was associated with diarrhea status, not high levels of the Shigella spp. ipaH gene.

High rate of detection of G8P[6] rotavirus in children with acute gastroenteritis in São Tomé and Príncipe

The burden of rotavirus infections greatly affects the low-income African countries. In the absence of epidemiological data on pediatric diarrhea in São Tomé and Príncipe (STP), a study was conducted from August to December 2011. Rotavirus antigen was detected in 36.7 % of the collected fecal samples (87/237). G8P[6] was identified as the predominant genotype (71.1 % detection rate), while G1P[8] represented only 8.4 %. Phylogenetic analysis of VP7 G8 strains showed clustering within lineage G8d, while VP4 P[6] strains clustered within lineage 1a. Our results represent the first report on rotavirus from STP and show one of the highest detection rates of G8 rotaviruses worldwide.

Review of global rotavirus strain prevalence data from six years post vaccine licensure surveillance: is there evidence of strain selection from vaccine pressure?

Comprehensive reviews of pre licensure rotavirus strain prevalence data indicated the global importance of six rotavirus genotypes, G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]. Since 2006, two vaccines, the monovalent Rotarix (RV1) and the pentavalent RotaTeq (RV5) have been available in over 100 countries worldwide. Of these, 60 countries have already introduced either RV1 or RV5 in their national immunization programs. Post licensure vaccine effectiveness is closely monitored worldwide. This review aimed at describing the global changes in rotavirus strain prevalence over time. The genotype distribution of the nearly 47,000 strains that were characterized during 2007-2012 showed similar picture to that seen in the preceding period. An intriguing finding was the transient predominance of heterotypic strains, mainly in countries using RV1. Unusual and novel antigen combinations continue to emerge, including some causing local outbreaks, even in vaccinated populations. In addition, vaccine strains have been found in both vaccinated infants and their contacts and there is evidence for genetic interaction between vaccine and wild-type strains. In conclusion, the post-vaccine introduction strain prevalence data do not show any consistent pattern indicative of selection pressure resulting from vaccine use, although the increased detection rate of heterotypic G2P[4] strains in some countries following RV1 vaccination is unusual and this issue requires further monitoring.