Genotyping of rotavirus isolates collected from children less than 5 years of age admitted for diarrhoea at the Yangon Children's Hospital, Myanmar
Introduction
Globally, 3–5 billion cases of acute gastroenteritis with nearly 2 million deaths occur each year in children under 5 years of age [1]. Most diarrhoeal episodes in children are due to viral infection and account for up to 70% of all events [2]. Rotavirus infection is the most common cause of severe, dehydrating, gastroenteritis among children worldwide. In developing countries, approximately 1400 children die from rotavirus infections each day, with an estimated 600,000 annually. In developing and developed countries, rotavirus is estimated to cause more than 2 million hospitalization every year [2], [3].
From 1988 to 1990, a WHO sponsored case–control study investigating the aetiology of acute diarrhoea in children under 3 years of age was conducted at the Yangon Children's Hospital. This hospital-based study revealed that rotavirus infection was responsible for 22% of all diarrhoeal hospitalizations in children under 3 years of age [4]. However, this initial study was likely an underestimate since a subsequent study conducted from January 2002 to December 2003 in Yangon showed that the rate of rotavirus detection in hospitalized children with diarrhoea more than doubled from 22% to 50% [5].
Rotavirus is a segmented, double-stranded RNA virus, that has three shells, an outer capsid, an inner capsid and a core which surround the 11 segments of double-stranded RNA, that encode for six structural proteins (VP1–VP4, VP6, VP7) and six non-structural proteins (NSP1–NSP6). Two structural proteins, VP7 (the glycoprotein or G protein) and VP4 (the protease-cleaved protein or P protein), make up the outer shell and are considered important for vaccine development since they define the serotype of the virus and are the major antigens involved in virus neutralization [6]. Because the genes encoding these proteins segregate independently of each other during reassortment, a dual-serotyping system to account for the specificities of both VP7 and VP4 has been adopted [7]. Thus the classification of rotaviruses is based on differences in the VP7 (G) and VP4 (P) capsid proteins. G serotypes 1–4, and P genotypes P[8] and P[4] predominate worldwide.
The diversity of rotavirus strains due in part to its ability to naturally reassort the segmented genome, together with the incomplete global geographical picture of this diversity poses a problem that candidate vaccines developed over years, may differ from those currently in circulation; and thus the vaccine used could have little or no effect on the indicated population. This highlights the need of updated data on the types and distribution of rotavirus strains circulating in regions where rotavirus related mortality and morbidity are major health problems and vaccines are most needed. This report summarizes rotavirus epidemiological data collected over 2 years (2004–2005) from Yangon Children's Hospital in Yangon, Myanmar. To complement the knowledge of rotavirus disease in this country, we describe the seasonality and genotypic characteristics of rotavirus strains responsible for acute gastroenteritis in children less than 5 years of age.
Section snippets
Materials and methods
Faecal specimens were collected from a total of 2179 children less than 5 years of age who were admitted with acute diarrhoea to Yangon Children's Hospital in Yangon, Myanmar. Acute diarrhoea was defined as the passage of loose or watery motions for more than three times in 24 h. Most of the children were from the Yangon City Development Area. Faecal samples were collected from January 2004 through December 2005. All faecal samples were collected and transported in cold boxes daily to the
Results
A total of 2179 faecal samples were collected from children aged less than 5 years, who presented to the hospital with acute diarrhoea during the study period from January 2004 through December 2005. During the year 2004, a total of 1004 stool specimens were collected for the analysis and of these 575 (57%) specimens were rotavirus positive. In 2005, 1175 stool specimens were collected for analysis, and 651 (55%) were rotavirus positive.
Discussion
The results of this study describe the first genotyping results for rotavirus strains associated with acute diarrhoea in infants and young children in Yangon, Myanmar. In Yangon, the rate of detection of rotavirus diarrhoea among hospitalized children has more than doubled, from 22% during the 1980s to over 50% in the years 2002–2005 [5]. The most common age group identified with acute rotavirus diarrhoea was 7–12 months age group. This study reveals that the under 1 year age group contributed
Conflict of interest
None to declare.
Funding sources
This work was performed under a collaborative agreement with the Program for Appropriate Technology in Health (PATH) and was funded in part by the GAVI Alliance and US CDC.
Acknowledgements
We wish to thank the Medical Superintendent and Staff of the Yangon Children's Hospital for their assistance in the conduct of this study.
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