Clinical severity of enteric viruses detected using a quantitative molecular assay compared to conventional assays in the Global Enteric Multicenter Study.

BACKGROUND: Quantitative molecular assays are increasingly used for detection of enteric viruses. METHODS: We compared the clinical severity using modified Vesikari score (mVS) of enteric viruses detected by conventional assays (enzyme immunoassays [EIA] for rotavirus and adenovirus 40/41 and conventional polymerase chain reaction for astrovirus, sapovirus, and norovirus) and a quantitative molecular assay (TaqMan Array Card [TAC]) among children aged 0-59 months in the Global Enteric Multicenter Study. For rotavirus and adenovirus 40/41, we compared severity between EIA-positive and TAC-positive cases assigned etiologies using different cycle threshold (CT) cutoffs. RESULTS: Using conventional assays, the median (interquartile range) mVS was 10 (8, 11) for rotavirus, 9 (7, 11) for adenovirus 40/41, 8 (6, 10) for astrovirus, sapovirus, and norovirus GII, and 7 (6, 9) for norovirus GI. Compared to rotavirus EIA-positive cases, the median mVS was 2 and 3 points lower for EIA-negative/TAC-positive cases with CT<32.6 and 32.6≤CT<35, respectively (p-value<.0001). Adenovirus 40/41 EIA-positive and EIA-negative/TAC-positive cases were similar, regardless of CT cutoff. CONCLUSIONS: Quantitative molecular assays compared to conventional assays, such as EIA, may influence severity of identified cases, especially for rotavirus. Cutoffs to assign etiology for quantitative assays should be considered in the design and interpretation of enteric virus studies.

Genomic analysis of clinical Aeromonas isolates reveals genetic diversity but little evidence of genetic determinants for diarrhoeal disease.

Aeromonas spp. are associated with a number of infectious syndromes in humans including gastroenteritis and dysentery. Our understanding of the genetic diversity, population structure, virulence determinants and antimicrobial resistance of the genus has been limited by a lack of sequenced genomes linked to metadata. We performed a comprehensive analysis of the whole genome sequences of 447 Aeromonas isolates from children in Karachi, Pakistan, with moderate-to-severe diarrhoea (MSD) and from matched controls without diarrhoea that were collected as part of the Global Enteric Multicenter Study (GEMS). Human-associated Aeromonas isolates exhibited high species diversity and extensive antimicrobial and virulence gene content. Aeromonas caviae, A. dhankensis, A. veronii and A. enteropelogenes were all significantly associated with MSD in at least one cohort group. The maf2 and lafT genes that encode components of polar and lateral flagella, respectively, exhibited a weak association with isolates originating from cases of gastroenteritis.

Diarrhea Case Surveillance in the Enterics for Global Health Shigella Surveillance Study: Epidemiologic Methods.

Background: Shigella is a leading cause of acute watery diarrhea, dysentery, and diarrhea-attributed linear growth faltering, a precursor to stunting and lifelong morbidity. Several promising Shigella vaccines are in development and field efficacy trials will require a consortium of potential vaccine trial sites with up-to-date Shigella diarrhea incidence data. Methods: The Enterics for Global Health (EFGH) Shigella surveillance study will employ facility-based enrollment of diarrhea cases aged 6-35 months with 3 months of follow-up to establish incidence rates and document clinical, anthropometric, and financial consequences of Shigella diarrhea at 7 country sites (Mali, Kenya, The Gambia, Malawi, Bangladesh, Pakistan, and Peru). Over a 24-month period between 2022 and 2024, the EFGH study aims to enroll 9800 children (1400 per country site) between 6 and 35 months of age who present to local health facilities with diarrhea. Shigella species (spp.) will be identified and serotyped from rectal swabs by conventional microbiologic methods and quantitative polymerase chain reaction. Shigella spp. isolates will undergo serotyping and antimicrobial susceptibility testing. Incorporating population and healthcare utilization estimates from contemporaneous household sampling in the catchment areas of enrollment facilities, we will estimate Shigella diarrhea incidence rates. Conclusions: This multicountry surveillance network will provide key incidence data needed to design Shigella vaccine trials and strengthen readiness for potential trial implementation. Data collected in EFGH will inform policy makers about the relative importance of this vaccine-preventable disease, accelerating the time to vaccine availability and uptake among children in high-burden settings.

The Enterics for Global Health (EFGH) Shigella Surveillance Study in Mali.

Background: In 2002, the Centre pour le Développement des Vaccins du Mali (CVD-Mali) was established as a partnership between the Mali Ministry of Health and the University of Maryland, Baltimore. Since its creation, CVD-Mali has been dedicated to describing the epidemiology of infectious diseases, supporting the development of vaccines, and training a team of local researchers. CVD-Mali participated in the Global Enteric Multicenter Study from 2007 to 2010 and the Vaccine Impact on Diarrhea in Africa study from 2015 to 2018, where the importance of Shigella as an enteric pathogen was established. Methods: In the Enterics for Global Health (EFGH) Shigella surveillance study, CVD-Mali will conduct Shigella surveillance at 4 health centers serving the population currently participating in a demographic surveillance system and will measure the local incidence of Shigella diarrhea and related outcomes in 6- to 35-month-old children. Antibiotic sensitivity patterns and the costs related to these cases will also be measured. Results: We anticipate reporting the number of diarrhea episodes that are positive by stool culture, the antibiotic susceptibility of these isolates, and the management and outcomes of these cases. Conclusions: In Mali, the EFGH study will contribute valuable information to understanding the burden of Shigella in this population. These data will inform the evaluation of vaccine candidates.

Symptomatic and asymptomatic enteric protozoan parasitic infection and their association with subsequent growth parameters in under five children in South Asia and sub-Saharan Africa.

BACKGROUND: Entamoeba histolytica, Giardia, and Cryptosporidium are common intestinal protozoan parasites that contribute to a high burden of childhood morbidity and mortality. Our study quantified the association between intestinal protozoan parasites and child anthropometric outcomes among children under-5. METHODS: We analyzed data from 7,800 children enrolled in the Global Enteric Multicenter Study (GEMS) across seven study sites that were positive for intestinal protozoan parasites between December 2007 and March 2011. Parasites were assessed using stool immunoassays (ELISA). We applied multiple linear regression to test the association between any or concurrent parasite and child anthropometric outcomes: length/height-for-age (HAZ), weight-for-age (WAZ), and weight-for-length/height (WHZ) z-score after 60 days of enrollment. Models were stratified by diarrheal symptoms, driven by the study design, and adjusted for potential covariates. FINDINGS: During the follow-up at day 60 after enrollment, child anthropometric outcomes, among the asymptomatic children showed, negative associations between Giardia with HAZ [ß: -0.13; 95% CI: -0.17, -0.09; p<0.001] and WAZ [ß -0.07; 95% CI: -0.11, -0.04; p<0.001], but not WHZ [ß: -0.02; 95% CI:-0.06, 0.02; p = 0.36]; Cryptosporidium with WAZ [ß: -0.15; 95% CI: -0.22, -0.09; p<0.001] and WHZ [ß: -0.18; 95%CI: -0.25, -0.12; p<0.001], but not with HAZ [ß: -0.03; 95% CI: -0.09, 0.04; p = 0.40]. For symptomatic children, no associations were found between Giardia and anthropometry; negative associations were found between Cryptosporidium with HAZ [ß: -0.17; 95% CI: -0.23, -0.11; p<0.001], WAZ [ß: -0.25; 95% CI: -0.31, -0.19; p<0.001] and WHZ [ß: -0.23; 95% CI: -0.30, -0.17; p<0.001]. Among the asymptomatic 24-59 months children, Giardia had a negative association with HAZ [ß: -0.09; 95% CI: -0.15, -0.04; p = 0.001]. No significant associations were found between E. histolytica with child growth. CONCLUSIONS: While some studies have found that Giardia is not associated with (or protective against) acute diarrhea, our findings suggest that it is associated with growth shortfall. This observation underscores the need for preventive strategies targeting enteric protozoan parasites among young children, to reduce the burden of childhood malnutrition.

Antenatal, intrapartum and infant azithromycin to prevent stillbirths and infant deaths: study protocol for SANTE, a 2×2 factorial randomised controlled trial in Mali.

INTRODUCTION: In high mortality settings, prophylactic azithromycin has been shown to improve birth weight and gestational age at birth when administered antenatally, to reduce the incidence of neonatal infections when administered intrapartum, and to improve survival when administered in infancy. Questions remain regarding whether azithromycin can prevent stillbirths, and regarding the optimal strategy for the delivery of azithromycin to pregnant women and their infants. METHODS AND ANALYSIS: Sauver avec l'Azithromycine en Traitant les Femmes Enceintes et les Enfants (SANTE) is a 2×2 factorial, individually randomised, placebo-controlled, double-masked trial in rural Mali. The primary aims are: (1A) to assess the efficacy of antenatal and intrapartum azithromycin on a composite outcome of stillbirths and infant mortality through 6-12 months and (1B) to assess the efficacy of azithromycin administered concurrently with the first and third doses of pentavalent vaccines (Penta-1/3) on infant mortality through 6-12 months. Pregnant participants (n=49 600) and their infants are randomised 1:1:1:1 to one of four treatment arms: (1) mother and infant receive azithromycin, (2) mother and infant receive placebo, (3) mother receives azithromycin and infant receives placebo or (4) mother receives placebo and infant receives azithromycin. Pregnant participants receive three single 2 g doses: two antepartum and one intrapartum. Infants receive a single 20 mg/kg dose at the Penta-1 and 3 visits. An additional cohort of 12 000 infants is recruited at the Penta-1 visit and randomised 1:1 to receive azithromycin or placebo at the same time points. The SANTE trial will inform guidelines and policies regarding the administration of antenatal and infant azithromycin using routine healthcare delivery platforms. ETHICS AND DISSEMINATION: This trial was approved by the Institutional Review Board at the University of Maryland School of Medicine (Protocol #HP-00084242) and the Faculté de Médecine et d'Odonto-Stomatologie in Mali. The findings of this trial will be published in open access peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT03909737.

Antibiotic-Prescribing Practices for Management of Childhood Diarrhea in 3 Sub-Saharan African Countries: Findings From the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018.

BACKGROUND: Despite antibiotic prescription being recommended for dysentery and suspected cholera only, diarrhea still triggers unwarranted antibiotic prescription. We evaluated antibiotic-prescribing practices and their predictors among children aged 2-59 months in the Vaccine Impact on Diarrhea in Africa (VIDA) Study performed in The Gambia, Mali, and Kenya. METHODS: VIDA was a prospective case-control study (May 2015-July 2018) among children presenting for care with moderate-to-severe diarrhea (MSD). We defined inappropriate antibiotic use as prescription or use of antibiotics when not indicated by World Health Organization (WHO) guidelines. We used logistic regression to assess factors associated with antibiotic prescription for MSD cases who had no indication for an antibiotic, at each site. RESULTS: VIDA enrolled 4840 cases. Among 1757 (36.3%) who had no apparent indication for antibiotic treatment, 1358 (77.3%) were prescribed antibiotics. In The Gambia, children who presented with a cough (adjusted odds ratio [aOR]: 2.05; 95% confidence interval [95% CI]: 1.21-3.48) were more likely to be prescribed an antibiotic. In Mali, those who presented with dry mouth (aOR: 3.16; 95% CI: 1.02-9.73) were more likely to be prescribed antibiotics. In Kenya, those who presented with a cough (aOR: 2.18; 95% CI: 1.01-4.70), decreased skin turgor (aOR: 2.06; 95% CI: 1.02-4.16), and were very thirsty (aOR: 4.15; 95% CI: 1.78-9.68) were more likely to be prescribed antibiotics. CONCLUSIONS: Antibiotic prescription was associated with signs and symptoms inconsistent with WHO guidelines, suggesting the need for antibiotic stewardship and clinician awareness of diarrhea case-management recommendations in these settings.

A Description of the Statistical Methods for the Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: Diarrheal diseases remain a health threat to children in low- and middle-income countries. The Vaccine Impact on Diarrhea in Africa (VIDA) study was a 36-month, prospective, matched case-control study designed to estimate the etiology, incidence, and adverse clinical consequences of moderate-to-severe diarrhea (MSD) in children aged 0-59 months. VIDA was conducted following rotavirus vaccine introduction at 3 censused sites in sub-Saharan Africa that participated in the Global Enteric Multicenter Study (GEMS) ∼10 years earlier. We describe the study design and statistical methods of VIDA and where they differ from GEMS. METHODS: We aimed to enroll 8-9 MSD cases every 2 weeks from sentinel health centers in 3 age strata (0-11, 12-23, 24-59 months) and 1 to 3 controls matched by age, sex, date of case enrollment, and village. Clinical, epidemiological, and anthropometric data were collected at enrollment and ∼60 days later. A stool specimen collected at enrollment was analyzed by both conventional methods and quantitative PCR for enteric pathogens. For the matched case-control study, we estimated the population-based, pathogen-specific attributable fraction (AF) and attributable incidence adjusted for age, site, and other pathogens, and identified episodes attributable to a specific pathogen for additional analyses. A prospective cohort study nested within the original matched case-control study allowed assessment of (1) the association between potential risk factors and outcomes other than MSD status and (2) the impact of MSD on linear growth. CONCLUSIONS: GEMS and VIDA together comprise the largest and most comprehensive assessment of MSD conducted to date in sub-Saharan Africa populations at highest risk for morbidity and mortality from diarrhea. The statistical methods used in VIDA have endeavored to maximize the use of available data to produce more robust estimates of the pathogen-specific disease burden that might be prevented by effective interventions.

Moderate-to-Severe Diarrhea and Stunting Among Children Younger Than 5 Years: Findings From the Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: Stunting affects >20% of children <5 years old worldwide and disproportionately impacts underserved communities. The Vaccine Impact on Diarrhea in Africa (VIDA) Study examined the association between an episode of moderate-to-severe diarrhea (MSD) and the risk of subsequent stunting in children <5 years living in 3 sub-Saharan African countries. METHODS: In this prospective, matched, case-control study among children <5 years, data were collected over 36 months from 2 groups. "Children with MSD" visited a health center within 7 days of illness onset experiencing ≥3 loose stools/day plus sunken eyes, poor skin turgor, dysentery, intravenous rehydration, or hospitalization. "Children without MSD" were enrolled from the community within 14 days of the index MSD child; they were diarrhea-free during the previous 7 days and were matched to the index case by age, sex, and residence. Using generalized linear mixed-effects models, we estimated the effect of an MSD episode on odds of being stunted, defined as height-for-age z-scores <-2, at a follow-up visit 2-3 months post-enrollment. RESULTS: The proportion of stunting at enrollment was similar when 4603 children with MSD and 5976 children without MSD were compared (21.8% vs 21.3%; P = .504). Among children not stunted at enrollment, those with MSD had 30% higher odds of being stunted at follow-up than children without MSD after controlling for age, sex, study site, and socioeconomic status (adjusted OR: 1.30; 95% CI: 1.05-1.62: P = .018). CONCLUSIONS: Children <5 years in sub-Saharan Africa without stunting experienced an increased likelihood of stunting during 2-3 months following an episode of MSD. Strategies for control of early childhood diarrhea should be integrated into programs intended to reduce childhood stunting.

Prevalence of Salmonella in Stool During the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018.

BACKGROUND: Non-typhoidal Salmonella (NTS) is a common cause of gastroenteritis in young children, with limited data on NTS serovars and antimicrobial resistance in Africa. METHODS: We determined the prevalence of Salmonella spp. and frequency of antimicrobial resistance among serovars identified in stools of 0-59 month-old children with moderate-to-severe diarrhea (MSD) and controls enrolled in the Vaccine Impact on Diarrhea in Africa (VIDA) Study in The Gambia, Mali, and Kenya in 2015-2018, and compared with data from the Global Enteric Multicenter Study (GEMS; 2007-2010) and the GEMS-1A study (2011). Salmonella spp. was detected by quantitative real-time PCR (qPCR) and culture-based methods. Identification of serovars was determined by microbiological methods. RESULTS: By qPCR, the prevalence of Salmonella spp. among MSD cases was 4.0%, 1.6%, and 1.9% and among controls was 4.6%, 2.4%, and 1.6% in The Gambia, Mali, and Kenya, respectively, during VIDA. We observed year-to-year variation in serovar distribution and variation between sites. In Kenya, Salmonella enterica serovar Typhimurium decreased (78.1% to 23.1%; P < .001) among cases and controls from 2007 to 2018, whereas serogroup O:8 increased (8.7% to 38.5%; P = .04). In The Gambia, serogroup O:7 decreased from 2007 to 2018 (36.3% to 0%; P = .001) but S. enterica serovar Enteritidis increased during VIDA (2015 to 2018; 5.9% to 50%; P = .002). Only 4 Salmonella spp. were isolated in Mali during all 3 studies. Multidrug resistance was 33.9% in Kenya and 0.8% in The Gambia across all 3 studies. Ceftriaxone resistance was only observed in Kenya (2.3%); NTS isolates were susceptible to ciprofloxacin at all sites. CONCLUSIONS: Understanding variability in serovar distribution will be important for the future deployment of vaccines against salmonellosis in Africa.

Drivers of Decline in Diarrhea Mortality Between GEMS and VIDA Studies.

BACKGROUND: Statistical modeling suggests that decreasing diarrhea-associated mortality rates in recent decades are largely attributed to improved case management, rotavirus vaccine, and economic development. METHODS: We examined data collected in 2 multisite population-based diarrhea case-control studies, both conducted in The Gambia, Kenya, and Mali: the Global Enteric Multicenter Study (GEMS; 2008-2011) and Vaccine Impact on Diarrhea in Africa (VIDA; 2015-2018). Population-level diarrhea mortality and risk factor prevalence, estimated using these study data, were used to calculate the attribution of risk factors and interventions for diarrhea mortality using a counterfactual framework. We performed a decomposition of the effects of the changes in exposure to each risk factor between GEMS and VIDA on diarrhea mortality for each site. RESULTS: Diarrhea mortality among children under 5 in our African sites decreased by 65.3% (95% confidence interval [CI]: -80.0%, -45.0%) from GEMS to VIDA. Kenya and Mali had large relative declines in diarrhea mortality between the 2 periods with 85.9% (95% CI: -95.1%, -71.5%) and 78.0% (95% CI: -96.0%, 36.3%) reductions, respectively. Among the risk factors considered, the largest declines in diarrhea mortality between the 2 study periods were attributed to reduction in childhood wasting (27.2%; 95% CI: -39.3%, -16.8%) and an increased rotavirus vaccine coverage (23.1%; 95% CI: -28.4%, -19.4%), zinc for diarrhea treatment (12.1%; 95% CI: -16.0%, -8.9%), and oral rehydration salts (ORS) for diarrhea treatment (10.2%). CONCLUSIONS: The VIDA study sites demonstrated exceptional reduction in diarrhea mortality over the last decade. Site-specific differences highlight an opportunity for implementation science in collaboration with policymakers to improve the equitable coverage of these interventions globally.

Giardia Detection and Codetection With Other Enteric Pathogens in Young Children in the Vaccine Impact on Diarrhea in Africa (VIDA) Case-Control Study: 2015-2018.

BACKGROUND: Giardia has been associated with reduced risk of diarrhea in children in low-resource settings, but the mechanism underlying this association is unknown. To assess whether Giardia may shape colonization or infection with other enteric pathogens and impact associations with diarrhea, we examined Giardia and enteric pathogen codetection among children <5 years old in Kenya, The Gambia, and Mali as part of the Vaccine Impact on Diarrhea in Africa study. METHODS: We tested for Giardia and other enteric pathogens using enzyme-linked immunosorbent assays and real-time polymerase chain reaction (PCR) on stool, respectively. We evaluated associations between Giardia and enteric pathogen detection using multivariable logistic regression models separately for children with moderate-to-severe diarrhea (MSD, cases) and free of diarrhea (controls). RESULTS: Among 11 039 enrolled children, Giardia detection was more common among controls (35%) than cases (28%, P < .001). Campylobacter coli/jejuni detection was associated with Giardia in controls in The Gambia (adjusted odds ratio [aOR] [95% confidence interval {CI}]: 1.51 [1.22‒1.86]) and cases across all sites (1.16 [1.00‒1.33]). Among controls, the odds of astrovirus (1.43 [1.05‒1.93]) and Cryptosporidium spp. (1.24 [1.06‒1.46]) detection were higher among children with Giardia. Among cases, the odds of rotavirus detection were lower in children with Giardia in Mali (.45 [.30‒.66]) and Kenya (.31 [.17‒.56]). CONCLUSIONS: Giardia was prevalent in children <5 years old and was associated with detection of other enteric pathogens, with differing associations in cases versus controls and by site. Giardia may affect colonization or infection by certain enteric pathogens associated with MSD, suggesting an indirect mechanism of clinical impact.

Epidemiology of Enteroaggregative, Enteropathogenic, and Shiga Toxin-Producing Escherichia coli Among Children Aged <5 Years in 3 Countries in Africa, 2015-2018: Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: To address knowledge gaps regarding diarrheagenic Escherichia coli (DEC) in Africa, we assessed the clinical and epidemiological features of enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), and Shiga toxin-producing E. coli (STEC) positive children with moderate-to-severe diarrhea (MSD) in Mali, The Gambia, and Kenya. METHODS: Between May 2015 and July 2018, children aged 0-59 months with medically attended MSD and matched controls without diarrhea were enrolled. Stools were tested conventionally using culture and multiplex polymerase chain reaction (PCR), and by quantitative PCR (qPCR). We assessed DEC detection by site, age, clinical characteristics, and enteric coinfection. RESULTS: Among 4840 children with MSD and 6213 matched controls enrolled, 4836 cases and 1 control per case were tested using qPCR. Of the DEC detected with TAC, 61.1% were EAEC, 25.3% atypical EPEC (aEPEC), 22.4% typical EPEC (tEPEC), and 7.2% STEC. Detection was higher in controls than in MSD cases for EAEC (63.9% vs 58.3%, P < .01), aEPEC (27.3% vs 23.3%, P < .01), and STEC (9.3% vs 5.1%, P < .01). EAEC and tEPEC were more frequent in children aged <23 months, aEPEC was similar across age strata, and STEC increased with age. No association between nutritional status at follow-up and DEC pathotypes was found. DEC coinfection with Shigella/enteroinvasive E. coli was more common among cases (P < .01). CONCLUSIONS: No significant association was detected between EAEC, tEPEC, aEPEC, or STEC and MSD using either conventional assay or TAC. Genomic analysis may provide a better definition of the virulence factors associated with diarrheal disease.

Etiology, Presentation, and Risk Factors for Diarrheal Syndromes in 3 Sub-Saharan African Countries After the Introduction of Rotavirus Vaccines From the Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: Diarrheal disease is heterogeneous, including watery diarrhea (WD) and dysentery, some cases of which become persistent diarrhea (PD). Changes in risk over time necessitate updated knowledge of these syndromes in sub-Saharan Africa. METHODS: The Vaccine Impact on Diarrhea in Africa (VIDA) study was an age-stratified, case-control study of moderate-to-severe diarrhea among children <5 years old in The Gambia, Mali, and Kenya (2015-2018). We analyzed cases with follow-up of about 60 days after enrollment to detect PD (lasting ≥14 days), examined the features of WD and dysentery, and examined determinants for progression to and sequelae from PD. Data were compared with those from the Global Enteric Multicenter Study (GEMS) to detect temporal changes. Etiology was assessed from stool samples using pathogen attributable fractions (AFs), and predictors were assessed using χ2 tests or multivariate regression, where appropriate. RESULTS: Among 4606 children with moderate-to-severe diarrhea, 3895 (84.6%) had WD and 711 (15.4%) had dysentery. PD was more frequent among infants (11.3%) than in children 12-23 months (9.9%) or 24-59 months (7.3%), P = .001 and higher in Kenya (15.5%) than in The Gambia (9.3%) or Mali (4.3%), P < .001; the frequencies were similar among children with WD (9.7%) and those with dysentery (9.4%). Compared to children not treated with antibiotics, those who received antibiotics had a lower frequency of PD overall (7.4% vs 10.1%, P = .01), and particularly among those with WD (6.3% vs 10.0%; P = .01) but not among children with dysentery (8.5% vs 11.0%; P = .27). For those with watery PD, Cryptosporidium and norovirus had the highest AFs among infants (0.16 and 0.12, respectively), while Shigella had the highest AF (0.25) in older children. The odds of PD decreased significantly over time in Mali and Kenya while increasing significantly in The Gambia. CONCLUSIONS: The burden of PD endures in sub-Saharan Africa, with nearly 10% of episodes of WD and dysentery becoming persistent.

Stunting Following Moderate-to-Severe Diarrhea Among Children Aged <5 Years in Africa Before and After Rotavirus Vaccine Introduction: A Comparison of the Global Enteric Multicenter Study and the Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: Studies conducted before rotavirus vaccine introduction found that moderate-to-severe diarrhea (MSD) in children aged <5 years was associated with stunting at follow-up. It is unknown whether the reduction in rotavirus-associated MSD following vaccine introduction decreased the risk of stunting. METHODS: The Global Enteric Multicenter Study (GEMS) and the Vaccine Impact on Diarrhea in Africa (VIDA) study, two comparable matched case-control studies, were conducted during 2007-2011 and 2015-2018, respectively. We analyzed data from 3 African sites where rotavirus vaccine was introduced after GEMS and before starting VIDA. Children with acute MSD (<7 days onset) were enrolled from a health center and children without MSD (diarrhea-free for ≥7 days) were enrolled at home within 14 days of the index MSD case. The odds of being stunted at a follow-up visit 2-3 months after enrollment for an episode of MSD was compared between GEMS and VIDA using mixed-effects logistic regression models controlling for age, sex, study site, and socioeconomic status. RESULTS: We analyzed data from 8808 children from GEMS and 10 579 from VIDA. Among those who were not stunted at enrollment in GEMS, 8.6% with MSD and 6.4% without MSD became stunted during the follow-up period. In VIDA, 8.0% with MSD and 5.5% children without MSD developed stunting. An episode of MSD was associated with higher odds of being stunted at follow-up compared with children without MSD in both studies (adjusted odds ratio [aOR], 1.31; 95% confidence interval [CI]: 1.04-1.64 in GEMS and aOR, 1.30; 95% CI: 1.04-1.61 in VIDA). However, the magnitude of association was not significantly different between GEMS and VIDA (P = .965). CONCLUSIONS: The association of MSD with subsequent stunting among children aged <5 years in sub-Saharan Africa did not change after rotavirus vaccine introduction. Focused strategies are needed for prevention of specific diarrheal pathogens that cause childhood stunting.

Survey-Based Assessment of Water, Sanitation, and Animal-Associated Risk Factors for Moderate-to-Severe Diarrhea in the Vaccine Impact on Diarrhea in Africa (VIDA) Study: The Gambia, Mali, and Kenya, 2015-2018.

BACKGROUND: Pediatric exposures to unsafe sources of water, unsafely managed sanitation, and animals are prevalent in low- and middle-income countries. In the Vaccine Impact on Diarrhea in Africa case-control study, we examined associations between these risk factors and moderate-to-severe diarrhea (MSD) in children <5 years old in The Gambia, Kenya, and Mali. METHODS: We enrolled children <5 years old seeking care for MSD at health centers; age-, sex-, and community-matched controls were enrolled at home. Conditional logistic regression models, adjusted for a priori confounders, were used to evaluate associations between MSD and survey-based assessments of water, sanitation, and animals living in the compound. RESULTS: From 2015 to 2018, 4840 cases and 6213 controls were enrolled. In pan-site analyses, children with drinking water sources below "safely managed" (onsite, continuously accessible sources of good water quality) had 1.5-2.0-fold higher odds of MSD (95% confidence intervals [CIs] ranging from 1.0 to 2.5), driven by rural site results (The Gambia and Kenya). In the urban site (Mali), children whose drinking water source was less available (several hours/day vs all the time) had higher odds of MSD (matched odds ratio [mOR]: 1.4, 95% CI: 1.1, 1.7). Associations between MSD and sanitation were site-specific. Goats were associated with slightly increased odds of MSD in pan-site analyses, whereas associations with cows and fowl varied by site. CONCLUSIONS: Poorer types and availability of drinking water sources were consistently associated with MSD, whereas the impacts of sanitation and household animals were context-specific. The association between MSD and access to safely managed drinking water sources post-rotavirus introduction calls for transformational changes in drinking water services to prevent acute child morbidity from MSD.

Prevalence, Clinical Severity, and Seasonality of Adenovirus 40/41, Astrovirus, Sapovirus, and Rotavirus Among Young Children With Moderate-to-Severe Diarrhea: Results From the Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: While rotavirus causes severe diarrheal disease in children aged <5 years, data on other viral causes in sub-Saharan Africa are limited. METHODS: In the Vaccine Impact on Diarrhea in Africa study (2015-2018), we analyzed stool from children aged 0-59 months with moderate-to-severe diarrhea (MSD) and without diarrhea (controls) in Kenya, Mali, and The Gambia using quantitative polymerase chain reaction. We derived the attributable fraction (AFe) based on the association between MSD and the pathogen, accounting for other pathogens, site, and age. A pathogen was attributable if the AFe was ≥0.5.The severity of attributable MSD was defined by a modified Vesikari score (mVS). Monthly cases were plotted against temperature and rainfall to assess seasonality. RESULTS: Among 4840 MSD cases, proportions attributed to rotavirus, adenovirus 40/41, astrovirus, and sapovirus were 12.6%, 2.7%, 2.9%, and 1.9%, respectively. Attributable rotavirus, adenovirus 40/41, and astrovirus MSD cases occurred at all sites, with mVS of 11, 10, and 7, respectively. MSD cases attributable to sapovirus occurred in Kenya, with mVS of 9. Astrovirus and adenovirus 40/41 peaked during the rainy season in The Gambia, while rotavirus peaked during the dry season in Mali and The Gambia. CONCLUSIONS: In sub-Saharan Africa, rotavirus was the most common cause of MSD; adenovirus 40/41, astrovirus, and sapovirus contributed to a lesser extent among children aged <5 years. Rotavirus- and adenovirus 40/41-attributable MSD were most severe. Seasonality varied by pathogen and location. Efforts to increase the coverage of rotavirus vaccines and to improve prevention and treatment for childhood diarrhea should continue.

Norovirus Disease Among Children <5 Years in 3 Sub-Saharan African Countries: Findings From the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018.

BACKGROUND: To address a paucity of data from sub-Saharan Africa, we examined the prevalence, severity, and seasonality of norovirus genogroup II (NVII) among children <5 years old in The Gambia, Kenya, and Mali following rotavirus vaccine introduction. METHODS: Population-based surveillance was conducted to capture medically-attended moderate-to-severe diarrhea (MSD) cases, defined as a child 0-59 months old passing ≥3 loose stools in a 24-hour period with ≥1 of the following: sunken eyes, poor skin turgor, dysentery, intravenous rehydration, or hospitalization within 7 days of diarrhea onset. Diarrhea-free matched controls randomly selected from a censused population were enrolled at home. Stools from cases and controls were tested for enteropathogens, including norovirus and rotavirus, by TaqMan quantitative polymerase chain reaction (PCR) and conventional reverse transcription PCR. We used multiple logistic regression to derive adjusted attributable fractions (AFe) for each pathogen causing MSD, which takes into consideration the prevalence in both cases and controls, for each site and age. A pathogen was considered etiologic if AFe was ≥0.5. In further analyses focusing on the predominant NVII strains, we compared rotavirus and NVII severity using a 20-point modified Vesikari score and examined seasonal fluctuations. RESULTS: From May 2015 to July 2018, we enrolled 4840 MSD cases and 6213 controls. NVI was attributed to only 1 MSD episode. NVII was attributed to 185 (3.8%) of all MSD episodes and was the sole attributable pathogen in 139 (2.9%); peaking (36.0%) at age 6-8 months with majority (61.2%) aged 6-11 months. MSD cases whose episodes were attributed to NVII alone compared with rotavirus alone were younger (median age, 8 vs 12 months, P < .0001) and had less severe illness (median Vesikari severity score, 9 vs 11, P = .0003) but equally likely to be dehydrated. NVII occurred year-round at all study sites. CONCLUSIONS: Infants aged 6-11 months bear the greatest burden of norovirus disease, with NVII predominating. An early infant vaccine schedule and rigorous adherence to guidelines recommended for management of dehydrating diarrhea may offer substantial benefit in these African settings.

Clinical and Epidemiologic Features of Cryptosporidium-Associated Diarrheal Disease Among Young Children Living in Sub-Saharan Africa: The Vaccine Impact on Diarrhea in Africa (VIDA) Study.

BACKGROUND: As part of the Vaccine Impact on Diarrhea in Africa (VIDA) Study, we examined the prevalence, clinical presentation, and seasonality of Cryptosporidium in children to understand its relative burden after the introduction of rotavirus vaccine. METHODS: VIDA was a 3-year, age-stratified, matched case-control study of medically attended acute moderate-to-severe diarrhea (MSD) in children aged 0-59 months residing in censused populations at sites in Kenya, Mali, and The Gambia. Clinical and epidemiologic data were collected at enrollment, and a stool sample was tested for enteropathogens by quantitative PCR. An algorithm was created based on the organism's cycle threshold (Ct) and association with MSD to identify the subset of Cryptosporidium PCR-positive (Ct <35) cases most likely to be attributed to MSD. Clinical outcomes were assessed at 2-3 months after enrollment. RESULTS: One thousand one hundred six (22.9%) cases of MSD and 873 controls (18.1%) were PCR positive for Cryptosporidium; 465 cases (42.0%) were considered attributable to Cryptosporidium, mostly among children 6-23 months. Cryptosporidium infections peaked in The Gambia and Mali during the rainy season, while in Kenya they did not have clear seasonality. Compared with cases with watery MSD who had a negative PCR for Cryptosporidium, cases with watery MSD attributed to Cryptosporidium were less frequently dehydrated but appeared more severely ill using a modified Vesikari scale (38.1% vs 27.0%; P < 0.001), likely due to higher rates of hospitalization and intravenous fluid administration, higher prevalence of being wasted or very thin very thin (23.4% vs 14.7%; P < 0.001), and having severe acute malnutrition (midupper arm circumference <115 mm, 7.7% vs 2.5%; P < 0.001). On follow-up, Cryptosporidium-attributed cases had more prolonged and persistent episodes (43.2% vs 32.7%; P <0 .001) and linear growth faltering (change in height-for-age z score between enrollment and follow-up: -0.29 vs -0.17; P < 0.001). CONCLUSIONS: The burden of Cryptosporidium remains high among young children in sub-Saharan Africa. Its propensity to cause illness and further impact children longer term by compromising nutritional status early in life calls for special attention to enable appropriate management of clinical and nutritional consequences.

Exploring Survey-Based Water, Sanitation, and Animal Associations With Enteric Pathogen Carriage: Comparing Results in a Cohort of Cases With Moderate-to-Severe Diarrhea to Those in Controls in the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018.

BACKGROUND: The magnitude of pediatric enteric pathogen exposures in low-income settings necessitates substantive water and sanitation interventions, including animal feces management. We assessed associations between pediatric enteric pathogen detection and survey-based water, sanitation, and animal characteristics within the Vaccine Impact on Diarrhea in Africa case-control study. METHODS: In The Gambia, Kenya, and Mali, we assessed enteric pathogens in stool of children aged <5 years with moderate-to-severe diarrhea and their matched controls (diarrhea-free in prior 7 days) via the TaqMan Array Card and surveyed caregivers about household drinking water and sanitation conditions and animals living in the compound. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using modified Poisson regression models, stratified for cases and controls and adjusted for age, sex, site, and demographics. RESULTS: Bacterial (cases, 93%; controls, 72%), viral (63%, 56%), and protozoal (50%, 38%) pathogens were commonly detected (cycle threshold <35) in the 4840 cases and 6213 controls. In cases, unimproved sanitation (RR, 1.56; 95% CI, 1.12-2.17), as well as cows (RR, 1.61; 95% CI, 1.16-2.24) and sheep (RR, 1.48; 95% CI, 1.11-1.96) living in the compound, were associated with Shiga toxin-producing Escherichia coli. In controls, fowl (RR, 1.30; 95% CI, 1.15-1.47) were associated with Campylobacter spp. In controls, surface water sources were associated with Cryptosporidium spp., Shigella spp., heat-stable toxin-producing enterotoxigenic E. coli, and Giardia spp. CONCLUSIONS: Findings underscore the importance of enteric pathogen exposure risks from animals alongside more broadly recognized water and sanitation risk factors in children.