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.

Dengue is an emerging disease in Nepal and was first observed as an outbreak in nine lowland districts in 2006. In 2010, however, a large epidemic of dengue occurred with 4,529 suspected and 917 serologically-confirmed cases and five deaths reported in government hospitals in Nepal. The collection of demographic information was performed along with an entomological survey and clinical evaluation of the patients. A total of 280 serum samples were collected from suspected dengue patients. These samples were subjected to routine laboratory investigations and IgM-capture ELISA for dengue serological identification, and 160 acute serum samples were used for virus isolation, RT-PCR, sequencing and phylogenetic analysis. The results showed that affected patients were predominately adults, and that 10% of the cases were classified as dengue haemorrhagic fever/ dengue shock syndrome. The genetic characterization of dengue viruses isolated from patients in four major outbreak areas of Nepal suggests that the DENV-1 strain was responsible for the 2010 epidemic. Entomological studies identified Aedes aegypti in all epidemic areas. All viruses belonged to a monophyletic single clade which is phylogenetically close to Indian viruses. The dengue epidemic started in the lowlands and expanded to the highland areas. To our knowledge, this is the first dengue isolation and genetic characterization reported from Nepal.