The first identification of rotavirus B from children and adults with acute diarrhoea in kathmandu, Nepal.

Rotavirus B (RVB) in the genus Rotavirus of the family Reoviridae is known to be a cause of acute gastroenteritis among children and adults in parts of Asia including China, India, Bangladesh and Myanmar. In a 15-month surveillance programme between March 2007 and May 2008, 3,080 stool specimens were collected from children and adults with acute gastroenteritis in an infectious disease hospital in Kathmandu, Nepal. In 25 (0.8%) specimens RVB was detected, for the first time in Nepal, by the use of polyacrylamide gel electrophoresis followed by confirmation with reverse-transcription PCR and sequencing. The strains detected in this study had very similar electropherotypes, and their VP7 sequences were almost identical and phylogenetically belonged to the Indo-Bangladeshi lineage which was distinct from the Chinese lineage. Thus, this study showed the circulation of RVB strains belonging to the Indo-Bangladeshi lineage in a broader region than previously documented, suggesting that this phylogenetic divide corresponded to the geographic divide created by the Himalayan Mountains. Further studies may be warranted to identify and characterize the RVB strains in northern Vietnam which is adjacent to southern China with a long and less mountainous border.

Continued Circulation of G12P[6] Rotaviruses Over 28 Months in Nepal: Successive Replacement of Predominant Strains.

Rotavirus A causes severe diarrhoea in infants and young children worldwide. The migration pattern (electropherotype) of the double-stranded RNA genome upon polyacrylamide gel electrophoresis has been used to define "strains" in molecular epidemiology. In temperate countries, distinct electropherotypes (strains) appear after the annual, off-seasonal interruption of rotavirus circulation. In Nepal, rotavirus circulated year-round and an uncommon genotype G12P[6] predominated and persisted, providing a unique opportunity to examine whether the same electropherotype (the same strain) persisted or new electropherotypes (new strains) emerged successively under the same G12P[6] predominance. A total of 147 G12P[6] rotaviruses, collected from diarrhoeal children in Nepal between 2007 and 2010, were classified into 15 distinct electropherotypes (strains). Of these, three electropherotypes (strains), LP1, LP24, and LP27, accounted for 10%, 32% and 38% of the G12P[6] rotaviruses, respectively. Each of the three major strains successively appeared, dominated, and disappeared. This study provided new evidence for the hypothesis that rotavirus constantly changes its strains to predominate in the local population even under conditions where a single genotype predominates and persists. Such dynamic strain replacement, the constant takeover of one predominant strain by another, fitter strain, is probably gives a competitive edge to the survival of rotavirus in nature.

Molecular epidemiology of rotavirus diarrhea among children aged <5 years in nepal: predominance of emergent G12 strains during 2 years.

A 2-year surveillance was performed in Kathmandu, Nepal, by collection of stool specimens from 1139 children aged <5 years who were hospitalized for acute diarrhea from November 2005 through October 2007. Of the 1139 samples, 379 (33%) had rotavirus strains identified by enzyme-linked immunosorbent assay; the most prevalent G type was G12, accounting for 50% of typed strains in 2005-2006 and 29% in 2006-2007, followed by G1 (26%) in 2005-2006 and by G9 (28%) and G2 (20%) in 2006-2007. The most prevalent P type was P[8], accounting for 47% of strains in 2005-2006 and 35% in 2006-2007, followed by P[6] (37% in 2005-2006 and 33% in 2006-2007) and P[4] (10% in 2005-2006 and 24% in 2006-2007). Of combined genotypes, G12P[6] was the most prevalent, accounting for 34% of strains in 2005-2006 and 24% in 2006-2007, followed by G1P[8] (23%) in 2005-2006 and G2P[4] (20%) in 2006-2007. An unusually high detection of G12 strains underscores the importance of continued surveillance of rotavirus strains.

Molecular epidemiology of rotavirus diarrhea among children and adults in Nepal: detection of G12 strains with P[6] or P[8] and a G11P[25] strain.

In anticipation of a rotavirus vaccine in Nepal, this study was undertaken to determine the distribution of the G and P serotypes and electropherotypes of rotaviruses in order to examine if there is any emerging serotype or unusual strain circulating in children and adults in Nepal. Of 1,315 diarrheal stool specimens, rotavirus was detected by an enzyme-linked immunosorbent assay in 116 (17%) of 666 patients less than 5 years of age, in 18 (7%) of 260 patients 5 to 14 years of age, and in 19 (5%) of 358 patients 15 years of age and older. Approximately 75% of rotavirus diarrhea occurred in children less than 5 years of age. Approximately 70% of rotaviruses found in each of the three age groups belonged to serotype G1P[8]. Interestingly, there were 29 (20%) G12 rotaviruses carrying either P[8] or P[6] and one (0.7%) G11 rotavirus carrying an unusual P[25] genotype. RNA polyacrylamide gel electrophoresis discriminated 19 strains (electropherotypes), among which there were three codominant strains carrying G1P[8] and long RNA patterns. Five electropherotypes were discriminated among G12 rotaviruses, all of which had long RNA patterns. The fact that 20% of rotaviruses were G12 strains carrying either P[8] or P[6] and had multiple electropherotypes suggest that G12 strains are not more rare strains but that they pose an emerging challenge to current and future vaccines. The presence of multiple strains as defined by electropherotypes suggests the richness of the rotavirus gene pool in Nepal, where unusual strains may continue to emerge.

Estimation of annual incidence, age-specific incidence rate, and cumulative risk of rotavirus gastroenteritis among children in Japan.

Rotavirus gastroenteritis is a common childhood infection, but the exact morbidity of the disease is not well described in Japan. We aimed at estimating morbidity measures to determine the magnitude of rotavirus gastroenteritis. An estimate for acute infectious gastroenteritis of all causes, to which rotavirus gastroenteritis belongs, has been available since the enactment in 1999 of the Law concerning the Prevention of Infectious Diseases and Medical Care of Patients with Infectious Diseases. Using this estimate and another estimate for the detection proportion of rotavirus among outpatients with acute infectious gastroenteritis, we calculated the annual incidence, the age-specific annual incidence rate, and the cumulative risk by the age of 6 years for rotavirus gastroenteritis. The latter estimate was obtained by a meta-analysis of four independent studies previously performed in Japan. According to our estimates, approximately 800,000 children in Japan under the age of 6 years visit pediatric practices or the outpatient department of hospitals because of rotavirus gastroenteritis at a rate of 11 cases/100 persons/year, and one in two children will visit pediatricians before they go to primary school. Such pediatrician visits most frequently occur at the age of 1 year (27 cases/100 persons/year). Thus, the magnitude of the burden of rotavirus disease among Japanese children is substantial.