Hospital-based surveillance and molecular epidemiology of rotavirus infection in Taiwan, 2005–2007

Impact of rotavirus vaccination on rotavirus hospitalizations in Taiwanese children

In 2006, two rotavirus vaccines were licensed in Taiwan but were not added to the national immunization schedule. National Health Insurance data from 2003 through 2017 were used to compare rotavirus-associated pediatric hospitalizations before and after vaccine introduction. Rotavirus hospitalization rates among children < 5 years of age significantly declined by 24% (95% confidence interval [CI] 23 - 25%) in post-vaccine compared to pre-vaccine rotavirus seasons. Rotavirus hospitalization rates declined by 42% (95% CI 39 - 44%) among infants < 12 months of age, and by 38% (95% CI 36 - 40%) among children 12 - 23 months of age. These findings suggest that, despite not being included in the national immunization schedule, rotavirus vaccines had a measurable impact on reducing rotavirus hospitalization burden among Taiwanese children.

Hospital-based surveillance of severe rotavirus gastroenteritis and rotavirus strains in young Taiwanese children

BACKGROUND/PURPOSE

Rotavirus remains a leading cause of pediatric gastroenteritis-related hospitalization. Surveillance studies have revealed that several major rotaviral genotypes are responsible for most cases of rotavirus gastroenteritis (RVGE). This study aimed to understand the characteristics of acute gastroenteritis (AGE) caused by rotavirus in young children in Taiwan.

METHODS

Ten hospitals in Taiwan were subjected to prospective hospital-based AGE surveillance during 2014-2017, and children younger than 5 years old who were hospitalized due to AGE were enrolled in the study. Medical and demographic variables were recorded and analyzed, and stool specimens were collected for rotavirus identification and genotyping via real-time RT-PCR. Non-rotavirus AGE age-matched controls were enrolled.

RESULTS

Surveillance identified 4747 young children hospitalized with AGE during this study period. The median age of these patients was 2.0 years. Rotavirus was detected in stool samples from 518 patients (10.9%). The prevalent months of RVGE in 2014, 2015, and 2017, wherein the rotavirus positivity rates exceeded 30%. The most common serotypes were G3P[8] (303/518, 58.9%) and G1P[8] (86/518, 16.6%). The percentage of G3P[8] increased from 4.9% in 2014 to 74.3% in 2016 (P < 0.0001), whereas the percentage of G1P[8] decreased from 61.0% in 2014 to 22.5% in 2015 (P < 0.0001). Compared with G3P[8], G1P[8] was associated with a significantly higher C-reactive protein level (P < 0.05).

CONCLUSION

Rotavirus remains a notable pathogenic etiology of childhood AGE and the G3P[8] serotype was dominant in Taiwan. This study highlighted the importance of rotavirus surveillance to ensure protective effectiveness against the circulating strains.

Intussusception-related Hospitalizations Among Infants Before and After Private Market Licensure of Rotavirus Vaccines in Taiwan, 2001-2013

INTRODUCTION

Rotavirus is a leading cause of acute gastroenteritis among Taiwanese children. Two globally licensed rotavirus vaccines recommended for inclusion in routine immunization programs that have been available for private market use in Taiwan since 2006 have been associated with a low risk of intussusception in postmarketing studies conducted in several countries. Our objective was to examine trends and characteristics of intussusception hospitalizations in Taiwan among children <12 months of age before and after rotavirus vaccine licensure to provide updated baseline and early postlicensure data.

METHODS

We extracted data on intussusception-related hospitalizations among children <12 months of age during 2001-2013 from the National Health Insurance Research Database. We examined patient demographics, clinical outcome and hospitalization trends, focusing on recommended ages for rotavirus vaccination (6-14, 15-24 and 25-34 weeks). We compared mean hospitalization rates for prevaccine licensure years 2001-2005 with those for postvaccine licensure years 2007-2013 using Poisson regression analysis.

RESULTS

During 2001-2013, 1998 intussusceptions hospitalizations were recorded. The mean age of hospitalization was 33 weeks. Almost all children recovered; 3 deaths occurred. The overall intussusception hospitalization rate was 75.1 per 100,000; seasonality was not evident. Hospitalization rates were greatest in children ≥25 weeks of age and occurred more frequently in boys. Prevaccine and postvaccine licensure trends in annual hospitalization rates did not significantly differ. However, mean hospitalization rates were lower during the postvaccine licensure period for children <12 months of age (rate ratio: 0.84, 95% confidence interval: 0.76-0.92) with the greatest decline among children 25-34 weeks of age (rate ratio: 0.66, 95% confidence interval: 0.55-0.78).

CONCLUSIONS

Infant intussusception in Taiwan occurs at a rate within the range of other Asian countries is rare among children <3 months of age, has a male predominance and does not have a clear seasonality pattern. We did not observe a postlicensure increase in intussusception hospitalization rates in children 6-14 weeks of age.

Novel G9 rotavirus strains co-circulate in children and pigs, Taiwan

Molecular epidemiologic studies collecting information of the spatiotemporal distribution of rotavirus VP7 (G) and VP4 (P) genotypes have shown evidence for the increasing global importance of genotype G9 rotaviruses in humans and pigs. Sequence comparison of the VP7 gene of G9 strains identified different lineages to prevail in the respective host species although some of these lineages appear to be shared among heterologous hosts providing evidence of interspecies transmission events. The majority of these events indicates the pig-to-human spillover, although a reverse route of transmission cannot be excluded either. In this study, new variants of G9 rotaviruses were identified in two children with diarrhea and numerous pigs in Taiwan. Whole genome sequence and phylogenetic analyses of selected strains showed close genetic relationship among porcine and human strains suggesting zoonotic origin of Taiwanese human G9 strains detected in 2014-2015. Although the identified human G9P[19] and G9P[13] rotaviruses represented minority strains, the repeated detection of porcine-like rotavirus strains in Taiwanese children over time justifies the continuation of synchronized strain surveillance in humans and domestic animals.

Global occurrence and emission of rotaviruses to surface waters

Group A rotaviruses (RV) are the major cause of acute gastroenteritis in infants and young children globally. Waterborne transmission of RV and the presence of RV in water sources are of major public health importance. In this paper, we present the Global Waterborne Pathogen model for RV (GloWPa-Rota model) to estimate the global distribution of RV emissions to surface water. To our knowledge, this is the first model to do so. We review the literature to estimate three RV specific variables for the model: incidence, excretion rate and removal during wastewater treatment. We estimate total global RV emissions to be 2 × 1018 viral particles/grid/year, of which 87% is produced by the urban population. Hotspot regions with high RV emissions are urban areas in densely populated parts of the world, such as Bangladesh and Nigeria, while low emissions are found in rural areas in North Russia and the Australian desert. Even for industrialized regions with high population density and without tertiary treatment, such as the UK, substantial emissions are estimated. Modeling exercises like the one presented in this paper provide unique opportunities to further study these emissions to surface water, their sources and scenarios for improved management.

Disease caused by rotavirus infection

Although rotavirus vaccines are available, rotaviruses remain the major cause of childhood diarrheal disease worldwide. The Rotarix (GlaxoSmithKline Biologicals Rixensart, Belgium) and RotaTeq (Merck and Co., Inc. Whitehouse Station, New Jersey, USA) vaccines are effective for reducing the morbidity and mortality of rotavirus infection. This article aims to assess the epidemiology of rotaviral gastroenteritis and the efficacy and effectiveness of licensed rotavirus vaccines. This review concludes by presenting challenges in the field that require further exploration by and perspectives from basic and translational research in the future.

Molecular epidemiology of human G2P[4] rotaviruses in Taiwan, 2004-2011

In 2006, two rotavirus vaccines (Rotarix and RotaTeq) became available on the private market in Taiwan. Although vaccine coverage is currently low, molecular surveillance of rotavirus strains can provide pertinent information for evaluation of the potential impact of vaccine introduction and infection control. During January 2008-December 2011, children aged <5 years hospitalized with acute gastroenteritis were enrolled from sentinel surveillance hospitals in three geographic areas of Taiwan. Fecal specimens collected from enrolled patients were tested for rotavirus by enzyme immunoassay and reverse transcriptase-polymerase chain reaction. For genotyping, gene specific primer sets were used to amplify and sequence the genes encoding the neutralization antigens, VP7 and VP4. The resulting sequences were then subjected to phylogenetic analysis. In brief, a total of 4,052 fecal specimens were tested and 742 (18%) samples were positive for rotavirus. The annual range of rotavirus positive specimens varied between 16% and 20.7%. Of all specimens, genotype G1P[8] (63.3%) was the predominant strain, followed by G2P[4] (12.5%), G3P[8] (11.7%), and G9P[8] (5.1%). Uncommon strains were also detected in low percentages. We observed that the rotavirus positivity rate steadily decreased from 21% to 16% during 2008-2010, then slightly increased to 20% in 2011, when an increase in the number of G2P[4] cases was observed. Sequence and phylogenetic analysis was carried out to help understand any potential changes of G2P[4] rotaviruses over time. A number of G2P[4] strains collected between 2004 and 2011 were analyzed in detail and our analyses showed marked genetic and antigenic variability in the VP7 and VP4 genes. The Taiwanese strains could be classified into two major G2 VP7 lineages (IV and V) and two major P[4] VP4 lineages (IV and V) and several minor sublineages within lineage IV. Lineage V within both G2 and P[4] represented newly recognized genetic variants of the respective genotypes. The distribution of individual combinations of the G2 and P[4] (sub)lineages showed some temporal variations. This study provides further evidence for the great genetic diversity among G2P[4] strains and helps understand the epidemiological trends of these strains among children in Taiwan.

Rotavirus and norovirus infections among acute gastroenteritis children in Morocco

Background

Acute gastroenteritis is a serious cause of child mortality and morbidity in resource-limited countries. A viral etiology is most common, and rotavirus and norovirus are reported to be the leading causative agents. There are still few epidemiological data on the simultaneous occurrence of these viruses in Morocco. The aim of this study was to provide useful epidemiological data on the gastroenteritis associated with rotavirus and norovirus among children aged less than 5 years.

Methods

From January to December 2011, 335 samples were tested for rotavirus and norovirus using enzyme-linked immunosorbent assay, reverse-transcription-polymerase chain reaction (RT-multiplex PCR) and real-time RT-PCR. Partial sequences of the norovirus were phylogenetically analyzed to determine the genotype.

Results

The overall rates of rotavirus and norovirus infections were 26.6% and 16.1%, respectively. Mixed viral infections were detected in 9 of 335 stool specimens (2.7%).

The most common genotype combination in the rotavirus strains was G1[P8] (51.7%), followed by G2[P4] (10.1%), G2[P8] (4.5%), G9[P8] (3.4%), G4[P8] (3.4%), and G1[P6] (2.3%). Among patients positive for norovirus, 42 (77.8%) tested positive for GII and 12 (22.2%) for GI. Thirty-three (78.6%) of the norovirus GII-positive cases were successfully characterized. Genotype GII.4 was the most prevalent (n = 27; 81.8%), followed by GII.3 (n = 2; 6.1%), GII.13 (n = 2; 6.1%), GII.16 (n = 1; 3%), and GII.17 (n = 1; 3%).

Conclusion

This study suggests that in Morocco, norovirus is the most frequent cause of acute gastroenteritis after rotavirus, but further enteric viruses need to be integrated in the surveillance system so that a conclusion could be drawn.

A retrospective analysis of acute gastroenteritis agents in children admitted to a university hospital pediatric emergency unit

BACKGROUND

Acute gastroenteritis is responsible observed in all age groups, especially infants and children. The etiology and clinical course of acute gastroenteritis may vary with age and etiological agents. In developing countries, the morbidity and mortality associated with infectious diarrhea is higher in children younger than five-years-of-age.

OBJECTIVES

The aim of this study was to determine the prevalence and seasonal distribution of the major agents of acute gastroenteritis in children who were admitted to a Turkish university hospital pediatric emergency unit during 2009.

PATIENTS AND METHODS

Seasonal distribution within a one year period and quantitative distribution were analyzed with demographic data and laboratory findings. A total of 644 subjects were enrolled in the study, with a mean age of 4.14 years. Pathogens were detected in 183 (28.4%) stool samples in children less than 16 years, admitted with acute gastroenteritis.

RESULTS

Pathogens were detected in 184 (28.4%) stool samples. The age distributions of the cases were 0 - 24 months (n = 59), 2 - 5 years (n = 100), and > 5 years (n = 25). The detection rate of rotavirus, norovirus and adenovirus were; 12.7% (75/588), 9.8% (51/520) and 4.9% (28/575), respectively. Bacterial agents were detected in 36 cases. The main agent was norovirus in the 0 - 24 months group (n = 25, 42.4%), and rotavirus for ages 2 - 5 years (n = 43, 43%) and > 5 years. On the monthly distribution, cases of rotavirus were found to be more frequent in the first four months of the year.

DISCUSSION

Viruses were the major pathogens in all age groups. Norovirus was the leading pathogen in the first two years. For the age groups 2 - 5 years and 6 - 16 years, rotavirus was the major pathogen.

Effectiveness of 2 rotavirus vaccines against rotavirus disease in Taiwanese infants

BACKGROUND

Two rotavirus (RV) vaccines (Rotarix and RotaTeq) are available on the private market in Taiwan, but are not recommended for routine use. We examined RV vaccine effectiveness (VE) against severe RV acute gastroenteritis (AGE) among Taiwanese infants to inform policymakers on the potential benefits of national RV vaccine introduction.

METHODS

From May 2009 to April 2011, a case-control assessment of VE against severe RV AGE was conducted at 3 hospital-based surveillance sites in Taiwan. Case-patients included children aged 8-35 months, hospitalized with laboratory-confirmed RV AGE. Controls included children age-matched within 1 month of age of the case-patient, hospitalized with RV-negative AGE or seen for non-AGE illnesses at the same hospitals. Vaccination history was confirmed through vaccination card or hospital record review. VE was calculated as (1--odds ratio of vaccination) × 100%.

RESULTS

We enrolled 184 case-patients with RV AGE, 904 RV-negative AGE and 909 non-AGE controls. Two-dose Rotarix series VE against RV gastroenteritis hospitalization was 90.4% [95% confidence interval (CI): 70.3%, 98.1%) and 92.5% (95% CI: 77.1%, 98.5%) with RV-negative AGE and non-AGE controls, respectively. Three-dose RotaTeq series VE was 96.8% (95% CI: 82.3%, 100%) and 97.1% (95% CI: 84%, 100%) with RV-negative AGE and non-AGE controls, respectively.

CONCLUSIONS

Both vaccines provided excellent protection against severe RV AGE hospitalization. Addition of RV vaccination into Taiwan's National Immunization Program could substantially decrease AGE hospitalizations among children <3 years. Our findings should help inform policymakers in Taiwan and other similar Asian countries when deciding whether to include RV vaccination into their national immunization programs.

Recommendations for rotavirus vaccine

Rotavirus infection has been the leading cause of gastroenteritis among children in Taiwan. Studies have shown that 40% of hospitalization for acute gastroenteritis can be prevented through the use of vaccines, including a live, attenuated monovalent rotavirus vaccine and a pentavalent, human-bovine reassortant rotavirus vaccine. In 2009, the World Health Organization suggested that rotavirus vaccine should be included in all national immunization programs. This review summarizes issues and recommendations discussed during an expert meeting in Taiwan. The recommendations included: (1) rotavirus vaccine should be offered to all healthy infants (including those without contraindications, such as immunodeficiency) at an appropriate age; (2) either monovalent or pentavalent vaccine can be administered concurrently with routine injected vaccines; (3) the administration of rotavirus vaccine must be administered at least 2 weeks prior to oral polio vaccination; (4) the first vaccine dose for infants should be administered between age 6 weeks and age 14 weeks 6 days and the course should be completed by age 8 months 0 day; (5) pentavalent vaccines can be administered at 2 months, 4 months, and 6 months while monovalent vaccines can be taken at 2 months and 4 months; (6) a combined use of monovalent and pentavalent vaccine is justified only when the previous dose is unavailable or unknown; and (7) rotavirus vaccines may be given to premature infants, human immunodeficiency virus infected infants and infants who have received or are going to receive blood products.

Global seasonality of rotavirus disease

BACKGROUND

A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before the introduction of widespread vaccination.

METHODS

We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus.

RESULTS

Among a total of 99 studies representing all 6 geographic regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high-income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P = 0.001) than geographic location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographic location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely.

CONCLUSION

While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease.

Evidence for Genetic Reassortment between Human Rotaviruses by Full Genome Sequencing of G3P[4] and G2P[4] Strains Co-circulating in India

Rotavirus A causes severe diarrhoea in infants and young children worldwide. Many unusual combinations of G and P genotypes have been observed in rotaviruses circulating in developing countries. Mixed infection of a single individual with more than one strain is a mechanism by which genetic reassortants are formed with unusual G and P combinations. However, few studies have provided direct evidence for the formation of such unusual strains as a result of co-infection of co-circulating strains. Here, we used full-genome sequencing to re-analyze a G3P[4] strain (107E1B) and a G2P[4] strain (116E3D) detected in India in 1993 and showed that 107E1B had virtually an identical nucleotide sequence with 116E3D, except the VP7 gene. Phylogenetic analysis revealed that the 107E1B VP7 gene was of typical human rotavirus origin, with a 99.3% nucleotide sequence identity with another Indian G3 VP7 gene. Thus, this study provided robust evidence for the formation of the G3P[4] strain through genetic reassortment in which a G2P[4] strain with a typical DS-1 genogroup background acquired the VP7 gene from a co-circulating G3 human rotavirus strain. This study established a basis on which to facilitate full genome sequence analysis of an increasing number of G3P[4] strains in China and elsewhere in the world.

Identification of porcine rotavirus-like genotype P[6] strains in Taiwanese children

The molecular characterization of genotype P[6] rotavirus strains collected from children admitted to hospital with acute dehydrating diarrhoea during a 6-year surveillance period in Taiwan is described in this study. In total, three G4P[6] strains, one G5P[6] and one G12P[6] were characterized by sequencing and phylogenetic analysis of the VP4, VP7, VP6 and NSP4 genes. Whilst all four genes of the single Taiwanese G12P[6] strain clustered with the respective genes of globally common human rotavirus strains, the G4 and G5 strains showed remarkable similarities to porcine rotavirus strains and putative porcine-origin human P[19] strains reported previously from Taiwan. The overall proportion of porcine rotavirus-like strains in Taiwan remains around 1 % among hospitalized children; however, the circulation and sporadic transmission of these heterotypic strains from pigs to humans could pose a public-health concern. Therefore, continuation of strain monitoring is needed in the vaccine era to detect any possible vaccine breakthrough events associated with the introduction of such heterologous rotavirus strains.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Putative canine origin of rotavirus strain detected in a child with diarrhea, Taiwan

Rotavirus G3P[3] strains have been reported from a variety of species including humans, cats, dogs, monkeys, goats, and cows. Here, we report the characterization of the first human G3P[3] rotavirus from East Asia identified in a 2-year-old child who was treated in a hospital's emergency ward in Taiwan in February 2005. Sequence and phylogenetic analysis demonstrated a close genetic relationship between the VP4, VP6, VP7, and NSP4 genes of Taiwanese G3P[3] strain 04-94s51 and an Italian canine strain isolated a decade ago, suggesting a canine origin for the Taiwanese strain. In contrast, the Taiwanese strain was only moderately related to well-characterized canine-origin human G3P[3] strains Ro1845 and HCR3, suggesting a distinct origin for the rotavirus strain from Taiwan.

Diverse origin of P[19] rotaviruses in children with acute diarrhea in Taiwan: Detection of novel lineages of the G3, G5, and G9 VP7 genes

We previously reported the detection of genotype P[19] rotavirus strains from children hospitalized with acute dehydrating diarrhea during a 5-year surveillance period in Taiwan. The characterization of five P[19] strains (0.4% of all typed), including three G3P[19], a novel G5P[19], and a unique G9P[19] genotype is described in this study. Phylogenetic analysis of the VP4, VP7, VP6, and NSP4 genes was performed, which demonstrated novel lineages for respective genotypes of the VP4 and the VP7 genes. The sequence similarities of the P[19] VP4 gene among Taiwanese human strains was higher (nt, 91.5-96.2%; aa, 93.7-97.6%) than to other P[19] strains (nt, 83.5-86.6%; aa, 89.4-94.1%) from different regions of the world. The VP7 gene of the three G3P[19] Taiwanese strains shared up to 93.4% nt and 97.5% aa identity to each other but had lower similarity to reference strain sequences available in GenBank (nt, <90.1%; aa, <95.6%). Similarly, the VP7 gene of the novel G5P[19] strain was only moderately related to the VP7 gene of reference G5 strains (nt, 82.2-87.3%; aa, 87.0-93.1%), while the VP7 gene of the single G9P[19] strain was genetically distinct from other known human and animal G9 rotavirus strains (nt, ≤ 92.0%; aa, ≤ 95.7%). Together, these findings suggest that the Taiwanese P[19] strains originated by independent interspecies transmission events. Synchronized surveillance of human and animal rotaviruses in Taiwan should identify possible hosts of these uncommon human rotavirus strains.

Projecting the effectiveness of RotaTeq® against rotavirus-related hospitalizations and deaths in six Asian countries

RotaTeq is an oral pentavalent rotavirus vaccine (RV5) that has shown high and consistent efficacy in preventing rotavirus gastroenteritis (RGE) in randomized clinical trials conducted mostly in industrialized countries. We projected the effectiveness of RV5 against RGE-related hospitalizations and deaths in 6 Asian countries by using a simple mathematical model. Model inputs included rotavirus surveillance data collected 2006-2007 in China, 2001-2002 in Hong Kong, 2005-2007 in India, 2005-2007 in South Korea, 2005-2007 in Taiwan, and 2001-2003 in Thailand; the numbers of rotavirus-related deaths in each country; and published rotavirus serotype-specific efficacy of RV5. The model projected an overall effectiveness in the region of 82% to 89% against RGE-related hospitalizations and a substantial reduction in RGE-related deaths, suggesting that RV5 could substantially reduce the burden of rotavirus disease in Asia.

Influence of birth rates and transmission rates on the global seasonality of rotavirus incidence

Rotavirus is a major cause of mortality in developing countries, and yet the dynamics of rotavirus in such settings are poorly understood. Rotavirus is typically less seasonal in the tropics, although recent observational studies have challenged the universality of this pattern. While numerous studies have examined the association between environmental factors and rotavirus incidence, here we explore the role of intrinsic factors. By fitting a mathematical model of rotavirus transmission dynamics to published age distributions of cases from 15 countries, we obtain estimates of local transmission rates. Model-predicted patterns of seasonal incidence based solely on differences in birth rates and transmission rates are significantly correlated with those observed (Spearman's ρ = 0.65, p < 0.05). We then examine seasonal patterns of rotavirus predicted across a range of different birth rates and transmission rates and explore how vaccination may impact these patterns. Our results suggest that the relative lack of rotavirus seasonality observed in many tropical countries may be due to the high birth rates and transmission rates typical of developing countries rather than being driven primarily by environmental conditions. While vaccination is expected to decrease the overall burden of disease, it may increase the degree of seasonal variation in the incidence of rotavirus in some settings.

Prevalence and factors associated with rotavirus infection among children admitted with acute diarrhea in Uganda

BACKGROUND

Rotavirus remains the commonest cause of severe dehydrating diarrhea among children worldwide. Children in developing countries die more because of several factors including poorer access to hydration therapy and greater prevalence of malnutrition. Hitherto, the magnitude of rotavirus disease in Uganda has remained unknown. This study was therefore done to determine the prevalence and factors associated with rotavirus infection among children aged 3-59 months admitted with acute diarrhea to paediatric emergency ward of Mulago Hospital, Uganda

METHODS

Three hundred and ninety children, aged between 3-59 months with acute diarrhoea were recruited. The clinical history, socio-demographic characteristics, physical examination findings and laboratory investigations were recorded. Stool samples were tested for rotavirus antigens using the DAKO IDEIA rotavirus EIA detection kit.

RESULTS

The prevalence of rotavirus infection was 45.4%. On multivariate analysis rotavirus was significantly associated with a higher education (above secondary) level of the mother [OR 1.8; 95% CI 1.1-2.7]; dehydration [OR 1.8; 95% CI 1.1-3.0] and breastfeeding [OR 2.6; 95% CI 1.4-4.0]. Although age was significantly associated with rotavirus on bivariate analysis; this association disappeared on multivariate analysis. No significant association was found between rotavirus infection and nutritional status, HIV status and attendance of day care or school.

CONCLUSIONS

Rotavirus infection is highly prevalent among children with acute diarrhoea admitted to Mulago Hospital in Uganda.