High burden of rotavirus gastroenteritis in young children in rural western Kenya, 2010-2011

Prevalence of rotavirus infection among children under five years at a tertiary institution in Nigeria

Background and objectives: Rotavirus is a significant cause of nonbacterial diarrhea, especially in infants and young children worldwide. This study evaluated the pattern of rotavirus infection in children under five years presenting with acute diarrhea in Abuja Teaching Hospital, Gwagwalada, Nigeria. Methodology: It was a cross-sectional descriptive study to describe the prevalence of rotavirus infection among children. The study enrolled children 1 to 59 months old with acute diarrhea attending General Paediatric Outpatient clinic and hospitalized in the Emergency Paediatric Unit of University of Abuja Teaching Hospital (UATH), Gwagwalada, Nigeria. Rotavirus antigen was detected in the stool by qualitative enzyme-linked immunosorbent assay (ELISA). Data were analyzed using IBM-SPSS version 25.0. Results: The study comprised of 414 diarrhoeal children aged 1–59 months, of which 226 (54.6%) were male and the mean age was 12.1 months. The overall rate of rotavirus infection was 43.0% (178/ 414). The rotavirus infection was slightly higher among females than in males (46.8% vs 39.8%; p=0.153). Children from upper and middle social classes were at 1.95 [CI=1.17–3.26] and 3.08[CI=1.77–5.34] times higher risks of rotavirus induced diarrhea than the children from the lower social class (p<0.005). Children whose mothers had post-secondary education were three times more at risk of rotavirus diarrhea [OR=3.70; CI=1.46–9.36] than those with primary or no formal education (p<0.05). Children who had never been vaccinated against rotavirus were four times more likely to suffer rotavirus infection than those who had been vaccinated [OR=3.96; 95%CI=1.13–13.89, p=0.032]. Conclusion: This study found that rotavirus was an important causative agent of diarrhea in children in Gwagwalada, Abuja. Due to low rotavirus vaccination status in children, rotavirus screening tests are necessary for children with acute diarrheal disease. J Med Sci. 2022; 16(2): 010. DOI: https://doi.org/10.55010/imcjms.16.020 *Correspondence: Felix Olaniyi Sanni, Department of Public Health, Fescosof Data Solutions, Ogun, Nigeria. Email: fescosofanalysis@gmail.com

Global Estimates of Rotavirus Hospitalizations Among Children Below 5 Years in 2019 and Current and Projected Impacts of Rotavirus Vaccination

BACKGROUND

Rotavirus vaccine impact on rotavirus hospitalizations is not well documented globally. We performed a systematic review to estimate the number of rotavirus hospitalizations that (1) occur annually, (2) are currently prevented by rotavirus vaccines, and (3) could be prevented with improved vaccine coverage and universal vaccine introduction.

METHODS

We systematically reviewed articles indexed in the PubMed database published from January 1, 2000, to December 31, 2019. We included all primary peer-reviewed studies with rotavirus hospitalization rates for children below 5 years that reported data prior to vaccine introduction, utilized at least one continuous year of data collection, and collected hospitalization data after 2000 using active surveillance. We grouped pre-vaccine country estimates by childhood mortality strata and calculated the median rate among each group. We then assigned the mortality stratum-specific hospitalization rates to each country and calculated the number of rotavirus hospitalizations by country, mortality strata, and World Health Organization region.

RESULTS

Our search strategy identified 4590 manuscripts, of which 32 were included in the final dataset. In 2019, an estimated 1 760 113 (interquartile range [IQR]: 1 422 645-2 925 372) rotavirus hospitalizations occurred globally, with 524 871 (IQR: 415 987-814 835) prevented by rotavirus vaccination. With universal introduction of rotavirus vaccines and increased vaccine coverage, we estimate that an additional 751 609 (IQR: 607 671-1 318 807) rotavirus hospitalizations can be prevented annually.

CONCLUSIONS

This analysis highlights the continued burden of rotavirus hospitalizations among children below 5 years. A large, preventable proportion of this burden could be eliminated by expanding introductions to new countries and increasing rotavirus vaccine coverage to levels seen with other childhood vaccinations.

Antimicrobial resistance including Extended Spectrum Beta Lactamases (ESBL) among E. coli isolated from kenyan children at hospital discharge

Background

Children who have been discharged from hospital in sub-Saharan Africa remain at substantial risk of mortality in the post-discharge period. Antimicrobial resistance (AMR) may be an important factor. We sought to determine the prevalence and risk factors associated with AMR in commensal Escherichia coli(E. coli) from Kenyan children at the time of discharge.

Methodology/Principle findings

Fecal samples were collected from 406 children aged 1–59 months in western Kenya at the time of discharge from hospital and cultured for E. coli. Susceptibility to ampicillin, ceftriaxone, cefotaxime, ceftazidime, cefoxitin, imipenem, ciprofloxacin, gentamicin, combined amoxicillin/clavulanic acid, trimethoprim-sulfamethoxazole, azithromycin, and chloramphenicol was determined by disc diffusion according to guidelines from the Clinical and Laboratory Standards Institute (CLSI). Poisson regression was used to determine associations between participant characteristics and the presence of extended-spectrum beta-lactamases (ESBL) producing E. coli. Non-susceptibility to ampicillin (95%), gentamicin (44%), ceftriaxone (46%), and the presence of ESBL (44%) was high. Receipt of antibiotics during the hospitalization was associated with the presence of ESBL (aPR = 2.23; 95% CI: 1.29–3.83) as was being hospitalized within the prior year (aPR = 1.32 [1.07–1.69]). Open defecation (aPR = 2.02; 95% CI: 1.39–2.94), having a toilet shared with other households (aPR = 1.49; 95% CI: 1.17–1.89), and being female (aPR = 1.42; 95% CI: 1.15–1.76) were associated with carriage of ESBL E. coli

Conclusions/Significance

AMR is common among isolates of E. coli from children at hospital discharge in Kenya, including nearly half having detectable ESBL.

Children who have been hospitalized in sub-Saharan Africa remain at a high risk of death and morbidity for at least 6 months following discharge. These children may harbor AMR in commensal bacteria following hospitalization, which may be associated with poor outcomes. There are limited data describing AMR and risk factors that are associated with AMR carriage at hospital discharge. In this cross-sectional study of Kenyan children under 5 years of age discharged from hospitals, we found AMR to be high. Children who received antibiotics in the hospital, had limited access to improved sanitation, and who were female had the highest prevalence of ESBL-producing E. coli.

Impact of the Introduction of Rotavirus Vaccine on Hospital Admissions for Diarrhea Among Children in Kenya: A Controlled Interrupted Time-Series Analysis

Background

Monovalent rotavirus vaccine, Rotarix (GlaxoSmithKline), was introduced in Kenya in July 2014 and is recommended to infants as oral doses at ages 6 and 10 weeks. A multisite study was established in 2 population-based surveillance sites to evaluate vaccine impact on the incidence of rotavirus-associated hospitalizations (RVHs).

Methods

Hospital-based surveillance was conducted from January 2010 to June 2017 for acute diarrhea hospitalizations among children aged <5 years in 2 health facilities in Kenya. A controlled interrupted time-series analysis was undertaken to compare RVH pre– and post–vaccine introduction using rotavirus-negative cases as a control series. The change in incidence post–vaccine introduction was estimated from a negative binomial model that adjusted for secular trend, seasonality, and multiple health worker industrial actions (strikes).

Results

Between January 2010 and June 2017 there were 1513 and 1652 diarrhea hospitalizations in Kilifi and Siaya; among those tested for rotavirus, 28% (315/1142) and 23% (197/877) were positive, respectively. There was a 57% (95% confidence interval [CI], 8–80%) reduction in RVHs observed in the first year post–vaccine introduction in Kilifi and a 59% (95% CI, 20–79%) reduction in Siaya. In the second year, RVHs decreased further at both sites, 80% (95% CI, 46–93%) reduction in Kilifi and 82% reduction in Siaya (95% CI. 61–92%); this reduction was sustained at both sites into the third year.

Conclusions

A substantial reduction in RVHs and all-cause diarrhea was observed in 2 demographic surveillance sites in Kenya within 3 years of vaccine introduction.

Effectiveness of Monovalent Rotavirus Vaccine Against Hospitalization With Acute Rotavirus Gastroenteritis in Kenyan Children

BACKGROUND

Rotavirus remains a leading cause of pediatric diarrheal illness and death worldwide. Data on rotavirus vaccine effectiveness in sub-Saharan Africa are limited. Kenya introduced monovalent rotavirus vaccine (RV1) in July 2014. We assessed RV1 effectiveness against rotavirus-associated hospitalization in Kenyan children.

METHODS

Between July 2014 and December 2017, we conducted surveillance for acute gastroenteritis (AGE) in 3 Kenyan hospitals. From children age-eligible for ≥1 RV1 dose, with stool tested for rotavirus and confirmed vaccination history we compared RV1 coverage among rotavirus positive (cases) vs rotavirus negative (controls) using multivariable logistic regression and calculated effectiveness based on adjusted odds ratio.

RESULTS

Among 677 eligible children, 110 (16%) were rotavirus positive. Vaccination data were available for 91 (83%) cases; 51 (56%) had 2 RV1 doses and 33 (36%) 0 doses. Among 567 controls, 418 (74%) had vaccination data; 308 (74%) had 2 doses and 69 (16%) 0 doses. Overall 2-dose effectiveness was 64% (95% confidence interval [CI], 35%-80%); effectiveness was 67% (95% CI, 30%-84%) for children aged <12 months and 72% (95% CI, 10%-91%) for children aged ≥12 months. Significant effectiveness was seen in children with normal weight for age, length/height for age and weight for length/height; however, no protection was found among underweight, stunted, or wasted children.

CONCLUSIONS

RV1 in the Kenyan immunization program provides significant protection against rotavirus-associated hospitalization which persisted beyond infancy. Malnutrition appears to diminish vaccine effectiveness. Efforts to improve rotavirus uptake and nutritional status are important to maximize vaccine benefit.

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.

Trends in diarrhea hospitalizations among infants at three hospitals in Tanzania before and after rotavirus vaccine introduction

BACKGROUND

The Tanzania Ministry of Health introduced monovalent human rotavirus vaccine in January 2013, to be administered at ages 6 and 10 weeks. Data suggest there was high vaccine uptake. We used hospital ward registers from 3 hospitals to examine trends in diarrhea hospitalizations among infants before and after vaccine introduction.

METHODS

Ward registers from Dodoma Regional Referral Hospital (Central Tanzania), and two hospitals in Mbeya (Southwest area), Mbeya Zonal Referral Hospital and Mbalizi Hospital, were used to tally admissions for diarrhea among children by age group, month and year. Rotavirus surveillance had started at these hospitals in early 2013; the proportion of infants enrolled and rotavirus-EIA positive were examined by month to determine peak periods of rotavirus disease post-vaccine introduction.

RESULTS

Registers were available for 2-4 prevaccine years and 2-3 post introduction years. At Dodoma Regional Referral Hospital, compared with the mean of 2011 and 2012, diarrhea hospitalizations among infants were 26% lower in 2015 and 58% lower in 2016. The diarrhea peak shifted later in the year first by 1 and then by 2-3 months from prevaccine. At the Mbeya hospitals, the number of diarrhea admissions in prevaccine period varied substantially by year. At Mbeya Referral Hospital, diarrhea hospitalizations among infants were lower by 25-37% in 2014 and 11-26% in 2015, while at Mbalizi Hospital, these hospitalizations were 4% lower in 2014 and 14% higher in 2015. Rotavirus testing data demonstrated a lowering of the prevaccine peak, a shift in timing of the peak months and indicated that other diarrheal peaks in post-introduction years were not due to rotavirus.

CONCLUSIONS

In this ecological evaluation, total diarrhea hospitalizations among infants were lower (≥25% lower in ≥1 year) following introduction in 2 of 3 hospitals. There are challenges in using ward registers to ascertain possible impact of rotavirus vaccine introduction on trends in hospitalizations for treatment of all diarrheal illness.

Impact of rotavirus vaccine on rotavirus diarrhoea in countries of East and Southern Africa

BACKGROUND

Established in 2006 with four countries conducting hospital-based rotavirus surveillance, the African rotavirus surveillance network has expanded over subsequent years. By 2015, 14 countries in the World Health Organization (WHO) East and Southern Africa sub-region (Eritrea, Ethiopia, Kenya, Lesotho, Madagascar, Mauritius, Namibia, Rwanda, Seychelles, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe) were participating in the rotavirus surveillance network coordinated by WHO. We monitored the proportion of rotavirus diarrhoea among children under five years of age who were hospitalized for diarrhoea in the sentinel hospitals from 2010 to 2015 among countries that introduced rotavirus vaccine during or before 2013 (Rwanda, Tanzania, Zambia and Ethiopia) and compared with the other countries in the network.

METHODS

Children under the age of five years hospitalized due to acute diarrhoea were enrolled into the sentinel surveillance system and had stool samples collected and tested for rotavirus antigens by enzyme immunoassay. We described trends in rotavirus positivity among tested stool samples before and after rotavirus vaccine introduction.

RESULTS

In countries that introduced rotavirus vaccine by 2013 (Rwanda, Tanzania, Zambia and Ethiopia), average rotavirus vaccine coverage from 2010 to 2015 improved from 0% in 2010 and 2011, 13% in 2012, 46% in 2013, 83% in 2014 to 90% in 2015. Annual average rotavirus positivity from 2010 to 2015 was 35%, 33%, 38%, 28%, 27%, and 19%, respectively. In countries that introduced rotavirus vaccine after 2013 or had not introduced by 2015, average rotavirus vaccine coverage was 0% in 2010-2013, 13% in 2014 and 51% in 2015. In these countries, rotavirus positivity was 44% in 2010, 32% in 2011, 33% in 2012, 41% in 2013, 40% in 2014 and 25% in 2015.

CONCLUSION

Countries that introduced rotavirus vaccine by 2013 had a lower proportion of rotavirus positive hospitalizations in 2013-2015 as compared to those that had not introduced rotavirus vaccine by 2013. The decrease in rotavirus positivity was inversely related to increase in rotavirus vaccine coverage showing impact of rotavirus vaccines.

Estimated reductions in hospitalizations and deaths from childhood diarrhea following implementation of rotavirus vaccination in Africa

INTRODUCTION

Rotavirus is the leading cause of hospitalizations and deaths from diarrhea. 33 African countries had introduced rotavirus vaccines by 2016. We estimate reductions in rotavirus hospitalizations and deaths for countries using rotavirus vaccination in national immunization programs and the potential of vaccine introduction across the continent. Areas covered: Regional rotavirus burden data were reviewed to calculate hospitalization rates, and applied to under-5 population to estimate baseline hospitalizations. Rotavirus mortality was based on 2013 WHO estimates. Regional pre-licensure vaccine efficacy and post-introduction vaccine effectiveness studies were used to estimate summary effectiveness, and vaccine coverage was applied to calculate prevented hospitalizations and deaths. Uncertainties around input parameters were propagated using boot-strapping simulations. In 29 African countries that introduced rotavirus vaccination prior to end 2014, 134,714 (IQR 112,321-154,654) hospitalizations and 20,986 (IQR 18,924-22,822) deaths were prevented in 2016. If all African countries had introduced rotavirus vaccines at benchmark immunization coverage, 273,619 (47%) (IQR 227,260-318,102) hospitalizations and 47,741 (39%) (IQR 42,822-52,462) deaths would have been prevented. Expert commentary: Rotavirus vaccination has substantially reduced hospitalizations and deaths in Africa; further reductions are anticipated as additional countries implement vaccination. These estimates bolster wider introduction and continued support of rotavirus vaccination programs.

Early impact of rotavirus vaccine in under 5year old children hospitalized due to diarrhea, Swaziland

BACKGROUND

Swaziland introduced rotavirus vaccine in the National Immunization Program, in May 2015, with the objective of reducing the burden of rotavirus diarrheal disease. We monitored the early impact of the vaccine in reducing rotavirus diarrhea.

METHODS

We conducted sentinel rotavirus surveillance from January 2013 to December 2016 in children under five years of age admitted due to diarrhea attending Mbabane Government Referral Hospital in the Hhohho Region and Raleigh Fitkin Memorial Hospital in the Manzini Region. All cases had stool samples collected and tested for rotavirus antigen by enzyme immunoassay.

RESULTS

Between 2013 and 2016, 596 samples were collected and tested. Rotavirus positivity reduced from average of 50.8% (172/338) (in 2013-2014 (pre vaccine period)) to 29% (24/82) in 2016, post-vaccine introduction. The median age of children with rotavirus infection increased from average of 10months in 2013-2014 to 13.7months in 2016. The peak season for all-cause diarrhea and rotavirus-specific hospitalizations among children under five years of age was June-August in all years with a blunting of the peak season in 2016. Rotavirus positivity among children 0-11months reduced from an average of 49% in 2013-2014 (116/236) to 33% (15/45) in 2016, a 33% reduction following rotavirus vaccine introduction.

CONCLUSION

There has been a rapid reduction of all-cause diarrhea and rotavirus hospitalizations in Swaziland, particularly in young children and during the rotavirus season, after the introduction rotavirus vaccine. Continued surveillance is needed to monitor the long-term impact of rotavirus vaccine introduction.

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

Introduction

Rotavirus is the leading cause of severe diarrhoea among infants and young children. Each year more than 611 000 children die from rotavirus gastroenteritis, and two million are hospitalized, worldwide. In Kenya, the impact of recent rotavirus vaccinations on morbidities has not been estimated. The study aimed at determining the prevalence and identity of rotavirus strains isolated from rotavirus-associated diarrhoea in vaccinated children presenting with acute gastroenteritis.

Methods

Two hundred and ninety eight specimen from children presented at Gertrude Childrens’ Hospital from January to June 2012 were tested by EIA (Enzyme-linked Immunosorbent Assay) for rotavirus antigens. Molecular characterization was conducted on rotavirus-positive specimens. Extracted viral RNA was separated by polyacrylamide gel electrophoresis (PAGE) and the specific rotavirus VP4 (P-types) and VP7 (G-types) determined.

Results

The prevalence rate of rotavirus was 31.5% (94/298). Of the rotavirus dsRNA, 57 (60.1%) gave visible RNA profiles, 38 (40.4%) assigned long electropherotypes while 19 (20.2%) were short electropherotypes. The strains among the vaccinated were G3P [4], G12P [6], G3P [6], G9P [4], G mixed G9/3P [4] and G1/3P [4]. Specifically, the G genotypes were G9/3 (5.3%), G9 (4.3%), G3 (4.3%), G12 (2.1%) and mixed G1/3 (1.1%). The P genotypes detected were P [4] (5.3%) and P [6] (5.3%).

Conclusion

The present study demonstrates diversity in circulating genotypes with emergence of genotypes G3, G9, G12 and mixed genotypes G9/3 and recommends that vaccines should be formulated with a broad range of strains to include G9 and G12.

Epidemiology, Seasonality and Factors Associated with Rotavirus Infection among Children with Moderate-to-Severe Diarrhea in Rural Western Kenya, 2008-2012: The Global Enteric Multicenter Study (GEMS)

Objective

To evaluate factors associated with rotavirus diarrhea and to describe severity of illness among children <5 years old with non-dysenteric, moderate-to-severe diarrhea (MSD) in rural western Kenya.

Methods

We analyzed data from children <5 years old with non-dysenteric MSD enrolled as cases in the Global Enteric Multicenter Study (GEMS) in Kenya. A non-dysenteric MSD case was defined as a child with ≥3 loose stools in 24 hrs. and one or more of the following: sunken eyes, skin tenting, intravenous rehydration, or hospitalization, who sought care at a sentinel health center within 7 days of illness onset. Rotavirus antigens in stool samples were detected by ELISA. Demographic and clinical information was collected at enrollment and during a single follow-up home visit at approximately 60 days. We analyzed diarrhea severity using a GEMS 17 point numerical scoring system adapted from the Vesikari score. We used logistic regression to evaluate factors associated with rotavirus infection.

Results

From January 31, 2008 to September 30, 2012, among 1,637 (92%) non-dysenteric MSD cases, rotavirus was detected in stools of 245 (15.0%). Rotavirus-positive compared with negative cases were: younger (median age, 8 vs. 13 months; p<0.0001), had more severe illness (median severity score, 9 vs 8; p<0.0001) and had to be hospitalized more frequently (37/245 [15.1%] vs. 134/1,392 [9.6%]), p <0.013). Independent factors associated with rotavirus infection included age 0–11 months old (aOR = 5.29, 95% CI 3.14–8.89) and presenting with vomiting ≥3 times/24hrs (aOR = 2.58, 95% CI [1.91–3.48]). Rotavirus was detected more commonly in warm and dry months than in the cool and rainy months (142/691 [20%] vs 70/673 [10%]) p<0.0001).

Conclusions

Diarrhea caused by rotavirus is associated with severe symptoms leading to hospitalization. Consistent with other settings, infants had the greatest burden of disease.

The aetiology of diarrhoea, pneumonia and respiratory colonization of HIV-exposed infants randomized to breast- or formula-feeding

BACKGROUND

Diarrhoea and pneumonia are common causes of childhood death in sub-Saharan Africa but there are few studies describing specific pathogens.

OBJECTIVES

The study aimed to describe the pathogens associated with diarrhoea, pneumonia and oropharyngeal colonization in children born to HIV-infected women (HIV-exposed infants).

METHODS

The Mashi Study randomized 1200 HIV-infected women and their infants to breastfeed for 6 months with ZDV prophylaxis or formula-feed with 4 weeks of ZDV. Children were tested for HIV by PCR at 1, 4, 7, 9 and 12 months and by ELISA at 18 months. Pre-defined subsets of children were sampled during episodes of diarrhoea (n = 300) and pneumonia (n = 85). Stool was tested for bacterial pathogens, rotavirus and parasites. Children with pneumonia underwent bacterial blood culture, and testing of nasopharyngeal aspirates for viral pathogens by PCR. Oropharyngeal swabs were collected from a consecutive subset of 561 infants at the routine 3-month visit for bacterial culture.

RESULTS

The median age (range) at sampling was 181 days for diarrhoea (0-730) and 140 days for pneumonia (2-551). Pathogens were identified in 55 (18%) children with diarrhoea and 32 (38%) with pneumonia. No differences in pathogens by child HIV status (HIV-infected vs HIV-uninfected) or feeding strategy were identified. Campylobacter was the most common diarrhoeal pathogen (7%). Adenovirus (22%) and other viruses (19%) were the primary pathogens isolated during pneumonias. More formula-fed infants had oropharyngeal colonization by pathogenic Gram-negative bacteria (16.8% vs 6.2%, P = 0.003), which was associated with a non-significant increased risk of pneumonia (OR 2.2, 95% CI 0.8-5.7).

CONCLUSION

A trend toward oropharyngeal bacterial colonization was observed in formula-fed infants. Although viruses were most commonly detected during pneumonia, respiratory colonization by Gram-negative bacteria may have contributed to pneumonia in formula-fed infants.

Population-Based Incidence Rates of Diarrheal Disease Associated with Norovirus, Sapovirus, and Astrovirus in Kenya

Background

Diarrheal diseases remain a major cause of mortality in Africa and worldwide. While the burden of rotavirus is well described, population-based rates of disease caused by norovirus, sapovirus, and astrovirus are lacking, particularly in developing countries.

Methods

Data on diarrhea cases were collected through a population-based surveillance platform including healthcare encounters and household visits in Kenya. We analyzed data from June 2007 to October 2008 in Lwak, a rural site in western Kenya, and from October 2006 to February 2009 in Kibera, an urban slum. Stool specimens from diarrhea cases of all ages who visited study clinics were tested for norovirus, sapovirus, and astrovirus by RT-PCR.

Results

Of 334 stool specimens from Lwak and 524 from Kibera, 85 (25%) and 159 (30%) were positive for norovirus, 13 (4%) and 31 (6%) for sapovirus, and 28 (8%) and 18 (3%) for astrovirus, respectively. Among norovirus-positive specimens, genogroup II predominated in both sites, detected in 74 (87%) in Lwak and 140 (88%) in Kibera. The adjusted community incidence per 100,000 person-years was the highest for norovirus (Lwak: 9,635; Kibera: 4,116), followed by astrovirus (Lwak: 3,051; Kibera: 440) and sapovirus (Lwak: 1,445; Kibera: 879). For all viruses, the adjusted incidence was higher among children aged <5 years (norovirus: 22,225 in Lwak and 17,511 in Kibera; sapovirus: 5,556 in Lwak and 4,378 in Kibera; astrovirus: 11,113 in Lwak and 2,814 in Kibera) compared to cases aged ≥5 years.

Conclusion

Although limited by a lack of controls, this is the first study to estimate the outpatient and community incidence rates of norovirus, sapovirus, and astrovirus across the age spectrum in Kenya, suggesting a substantial disease burden imposed by these viruses. By applying adjusted rates, we estimate approximately 2.8–3.3 million, 0.45–0.54 million, and 0.77–0.95 million people become ill with norovirus, sapovirus, and astrovirus, respectively, every year in Kenya.