Enweronu-Laryea, Christabel C. MRCPCH*†; Sagoe, Kwamena W. C. PhD‡; Mwenda, Jason M. PhD§; Armah, George E. PhD¶
From the *Department of Child Health, University of Ghana Medical School; †Korle Bu Teaching Hospital; ‡Department of Microbiology, University of Ghana Medical School, Accra, Ghana; §Africa Rotavirus Surveillance Network, WHO Regional Office for Africa, Djoue, Brazzaville, Republic of Congo; and ¶Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.
Accepted for publication June 24, 2013.
Funding was provided by World Health Organization through the African Rotavirus Surveillance Network. The authors have no other funding or conflicts of interest to disclose.
Address for correspondence: Christabel C. Enweronu-Laryea, Department of Child Health, University of Ghana Medical School, P.O. Box 4236, Accra, Ghana. E-mail: email@example.com.
Rotavirus is a major cause of acute gastroenteritis (AGE) globally. Local data on disease burden will guide recommendations for rotavirus vaccination and monitoring impact of the intervention.
Prospective surveillance for rotavirus gastroenteritis was conducted in 3 hospitals in southern Ghana during the period August 2006 to December 2011, as part of the African Rotavirus Surveillance Network. Clinical data and stool specimens were collected from children <5 years of age and hospitalized with AGE (defined as 3 or more watery stools for up to 7 days). Stool was tested for rotavirus by enzyme immunoassay and rotavirus genotype identified by reverse-transcriptase polymerase chain reaction.
We tested 3044 stool samples from 3939 children. Rotavirus was detected in 45.6%, 51.3% and 48.5% of cases at the primary, secondary and tertiary care hospital, respectively. Both genders were equally affected; 75% (2954/3939) of the cohort were aged 3–18 months. Overall, rotavirus was detected in 49.4% (1504/3044) of cases, caused over 30% of AGE hospitalizations all year round and up to 70% of cases during peak seasons. Peak season occurred during cool dry months in 2008, 2010 and 2011 and the rainy season in 2009. Mortality from AGE occurred in 1.5% (45/3044) of cases and 48.9% (22/45) of these were rotavirus positive.
Rotavirus causes significant morbidity and mortality in young Ghanaian children. As Ghana introduced rotavirus vaccination in the national immunization program in 2012, continued surveillance is required to monitor the impact of this intervention.
Diarrheal diseases are the second most common cause of death in children <5 years globally.1 Most diarrheal diseases in young children are caused by intestinal pathogens. There has been significant decline in bacterial and parasitic diarrhea-related morbidity and mortality in the last decade but much less so for viral diarrhea that is mostly caused by rotavirus.2–4 Improvements in home use of oral rehydration solutions, community hygienic practices and case management of children with acute gastroenteritis (AGE) have led to the decline in morbidity and mortality of nonviral AGE; but vaccination is considered the most effective public health strategy to reduce rotavirus disease burden.5
It is estimated that every year 2 million children are hospitalized and about half a million children die from rotavirus gastroenteritis.6,7 Ghana has a high burden of AGE and it is estimated that rotavirus gastroenteritis accounts for about 20% of all diarrheal deaths.2 Others have shown that rotavirus gastroenteritis accounted for 34% of diarrheal deaths in northern Ghana.8 The World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization recommends prioritization of rotavirus vaccination into national immunization programs in countries where diarrheal deaths account for >10% of mortality in children <5 years of age.9
Since 2006 Ghana has received support from WHO for active surveillance on burden of severe rotavirus gastroenteritis as part of the African Regional Rotavirus Surveillance Network. Rotavirus vaccination was included in the expanded program on immunization in Ghana in April 2012. This study shows the trends in the burden of severe rotavirus gastroenteritis in southern Ghana from 2006 to 2011 before vaccine introduction.
MATERIALS AND METHODS
The 24.6 million inhabitants of Ghana live in 10 administrative regions and are served by 3 teaching (tertiary) hospitals located in the north, middle and south of the country. The capital city Accra is in the south and has an estimated population of 4 million. Korle Bu Teaching hospital (KBTH) in Accra is the largest hospital in the country and provides tertiary pediatric services to children in southern regions of Ghana. Rotavirus surveillance started at KBTH in August 2006. It was extended to a regional referral children’s hospital in September 2007 and to a district hospital in January 2008. These 3 hospitals are within 10 km radius in Accra Metropolis and provide inpatient services for over 50% of hospitalized children in the city. The chosen hospitals provide Level I District hospital (DH), Level II Children’s hospital (CH) and Level III (KBTH) facility-based clinical services.
Children aged 0–59 months who were hospitalized for >24 hours with a primary diagnosis of AGE were eligible to be included in the study if their parents gave consent. For this study, AGE was defined as 3 or more watery stools within 24 hours that has lasted for ≤7 days. Children with bloody stools or those whose parents did not give consent were excluded. Sampling strategy consisted of continuous daily enrollment throughout the year at DH and only daytime enrollment (except weekends and statutory holidays) at CH and KBTH. Continuous enrollment was not logistically possible at CH and KBTH because of the excessive workload for available nurses after regular work hours. Participation in the study was voluntary and no incentive was given to encourage participation.
Data Collection and Laboratory Analysis
A standard questionnaire was used to collect demographic (date of birth, age, gender, date of hospitalization and discharge) and clinical (episodes of diarrhea, vomiting, body temperature, treatment given and outcome of hospitalization) data from the parents and hospital records. Data on all diarrheal hospitalizations for children <5 years of age were collected from the admissions and discharge register of participating hospitals.
Stool samples were collected in labeled screw-top containers no later than 7 days after the onset of the illness and within 48 hours of hospitalization. All stool specimens were sent to the University of Ghana Medical School Virology laboratory where they were stored at 4°C until testing for rotavirus antigens by an enzyme immunoassay (IDEIA kit, DAKO Diagnostics, United Kingdom) method. All rotavirus-positive specimens were sent to the Noguchi Memorial Institute of Medical Research reference virology laboratory for determination of rotavirus genotype by polyacrylamide gel electrophoresis as described by Herring et al10 and reverse-transcriptase polymerase chain reaction method as described by Armah et al.11 Quality control was ensured by retesting 10% of EIA-negative stool specimens at the reference laboratory.
All data were entered into a database using the Epi Info 3.5.1 (CDC, Atlanta, GA). Data analysis was by descriptive and inferential statistics using Stata version 10 (StataCorp, College Station, TX).
During the 65 months (August 2006 to December 2011) of surveillance at KBTH, 52 months (September 2007 to December 2011) at CH and 48 months (January 2008 to December 2011) at DH about 34,500 children <5 years were hospitalized in the 3 participating hospitals and 5101 (14.8%) of these had acute diarrheal diseases. We collected clinical data in 3939/5101 (77.2%) children and stool specimens for rotavirus testing in 3049/3939 (77.4%). Five stool specimens were insufficient for analysis, so a total of 3044 stool specimens were tested for rotavirus of which 1504 (49.4%) were positive.
Patients’ Characteristics and Level of Health Facility
Overall, we tested stools from 3044/5101 (60%) of all children <5 years of age hospitalized with AGE constituting 100% of cases at DH, 49% of cases at CH and 69% at KBTH as shown in Table 1. Younger children had higher stool collection rates than older children. Children aged <3 months, 3–18 months and 19–59 months constituted 6.8% (343/5101), 75% (3828/5101) and 18.2% (930/5101), respectively, of AGE hospitalizations.
Male children [1727/3044 (56.7%)] were more likely to be admitted with AGE than female children; however, there was no gender difference in the prevalence of AGE due to rotavirus [males 859/1727 (49.7%) and females 645/1317 (49.0%)]. The peak age for hospitalization with rotavirus AGE was 3–18 months as shown in Table 2. There was no difference in the age group distribution of rotavirus gastroenteritis between the 3 levels of health facilities (Fig. 1).
There were logistical problems with recruitment of subjects and stool specimen collection in the first 13 months (August 2006 to August 2007) of the surveillance. Thus, the analysis of rotavirus seasonality in this report is restricted to the period 2008–2011, when data collection was consistent (Figs 2 and 3). Rotavirus was detected in >30% of children hospitalized with AGE all year round and in up to 70% of AGE cases during diarrhea peak seasons. The peak diarrheal season occurred during the dry cool months (December to March) in 2008, 2010 and 2011 and during the rainy season (April to July) in 2009.
Among the 3939 children with clinical data collected 55 (1.4%) died, 45/3044 (1.5%) of those whose stool specimen were tested died and 22/1504 (1.5%) of those with rotavirus gastroenteritis died. Eighty-one percentage of all deaths occurred in children <18 months of age. Rotavirus was detected in the stool of 22/45 (48.9%) of those who died from AGE. Of the 22 rotavirus-associated deaths, 21/22 (95%) occurred in children aged 3–18 months [8/22 (3–5 months), 9/22 (6–11 months) and 4/22 (12–18 months)]. None of the children admitted at the Level I hospital died, while 14/22 (63.6%) of the deaths associated with EIA-positive rotavirus gastroenteritis occurred in the Level III hospital.
At the time of this report, rotavirus genotyping result was available for stools collected from August 2007 through February 2011. During this period, stools from 2278 children were tested by EIA and 1099 (48.2%) of these were positive for rotavirus. Of the 1099 EIA-positive specimens, 978 (88.9%) were polyacrylamide gel electrophoresis positive and hence had enough dsRNA for further analysis. Of the 978 specimens subjected to genotyping by reverse-transcriptase polymerase chain reaction, 876 (89.7%) could be assigned to a G or P genotype.
We identified 8 G genotypes (G1, G2, G3, G4, G8, G9, G10 and G12) and 3 P genotypes P, P and P among the 876 specimens that were subjected to reverse-transcriptase polymerase chain reaction. G1 (50.9%) and G2 (18.8%) were the most prevalent G types while P (36.1%) and P (30.7%) were the most prevalent P types. Mixed G (7.3%) and P (24.2%) genotypes were not uncommon. G1P, G3P and G2P were the most prevalent strains accounting for 28%, 9% and 7% of all strains, respectively. Most cases with nonmix G genotype rotavirus strains occurred in children <3 years of age; only 3 (25%) of 12 children aged >36 months had nonmixed G types. The age distribution of the genotypes among the children <36 months old is shown in Figure 4. There were only 3 cases with genotype data among children aged 36–59 months (G2–1, G3–1 and G10–1).
This study demonstrates the substantial burden of rotavirus gastroenteritis in Ghanaian children <5 years of age before vaccine introduction. Rotavirus disease caused over 50% of severe acute diarrhea hospitalizations in children aged 3–18 months, over 30% of all diarrhea hospitalizations at any time of the year and up to 70% of hospitalizations during the peak season of dry cool months. It is also a major cause of diarrheal mortality in children <5 years of age hospitalized with AGE in southern Ghana.
We contend that the data presented in this study are representative of the severe diarrhea burden of young children in southern Ghana. The referral facilities CH and KBTH provide hospital beds for over 50% of pediatric referrals in southern Ghana and we tested the stools of about 60% of all acute diarrhea hospitalizations. The age prevalence of rotavirus gastroenteritis was similar at all levels of health care delivery.
The prevalence (49.4%) of rotavirus gastroenteritis in this study is higher than that reported from sub-Saharan African countries,12 Middle Eastern region13 and western countries.14,15 The higher prevalence in our cohort could be explained by restrictions in our inclusion criteria. Most surveillance studies enroll children with history of diarrhea for up to 14 days; however, in this study, the inclusion criteria was only for those with history of diarrhea of no more than 7 days duration. The higher prevalence could be explained by the fact that children with rotavirus gastroenteritis excrete the virus maximally in the first week of the illness.16
The highest burden of rotavirus gastroenteritis was in children aged 3–24 months. This age group accounted for 91% (84% in 3–18 months of age, 7% in 19–24 months of age) of all rotavirus AGE cases. This finding is similar to what others have shown in Africa12 and other developing countries.17–19 A disturbing finding in this study is the prevalence of rotavirus gastroenteritis in infants aged 0–5 months. Over 25% of the youngest infants (0–3 months) and >50% of those aged 3–5 months had rotavirus gastroenteritis. This may reflect the exclusive breast-feeding practices of the population under study. In the latest (2008) Ghana Demographic and Health Survey,20 only 49.4% of children aged 4–5 months and <70% of those under 3 months of age were exclusively breastfed. Exclusive breast-feeding reduces the severity of gastrointestinal infections in young infants.
There was a higher proportion of rotavirus-related diarrheal deaths in this study than previously reported in Ghana.8,21 We cannot fully explain this finding except that the 2 previous studies were of shorter duration and might not have captured the real burden of rotavirus gastroenteritis over time.
The most prevalent genotype G1 caused severe diarrhea in only about 50% of children <5 months of age—the age group targeted for rotavirus immunization. The great diversity of rotavirus strains observed in this study especially in the young infants raises concerns about whether the vaccine strains that are predominantly G1P would evoke sufficient heterotypic protection against other strains not present in the vaccine. However, there are reports of cross-protection with natural infection and vaccine-induced immunity and this vaccine has been shown to offer significant protection against a range of genotypes.22–24 As Ghana introduces rotavirus vaccination into the routine immunization program, it is important to closely monitor vaccine performance against heterotypic strains in Ghana.
The major limitation of this study is that the 3 hospitals are in an urban setting; as such the data presented may not accurately represent the acute diarrhea burden in rural areas where hospitals are not easily accessible. Our data would have been more representative if 1 of the hospitals was in a rural setting but this would have been logistically difficult for the resources available for the study. Also, the exclusively daytime enrolment that excluded children presenting at weekends and night time at CH and KBTH may have missed severely affected children who may have died before they could be enrolled in the study.
In conclusion, rotavirus causes significant health burden for young Ghanaian children. Rotavirus vaccination has been recently introduced in the national expanded program on immunization. It is hoped that this surveillance study will be sustained over the years and possibly extended to rural settings so as to evaluate the impact of immunization over time.
The authors are grateful to Juanita Adams and Gifty Okine for their diligent work in specimen collection and data entry; Anna Aba Hayford, Makafui Seshie and Belinda Lartey for laboratory services.
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