Molecular Characterization of Group A Rotavirus Genotypes Circulating in Oman between 2009 and 2013

Oman is on the verge of introducing rotavirus vaccination for children. It will be part of the National EPI programme based on the data collected on the burden of disease and circulating rotavirus genotypes. In 2005 the predominant circulating genotype in Oman was G1P[8] but strain prevalence changes over time have been observed. (Observation briefly mentioned in the discussion) To receive more detailed information a 5 year study from January 2009 to December 2013 has been conducted to elucidate the temporal diversity of genotypes and to provide more recent information on the burden of rotavirus infection among hospitalized children less than five years of age. A total of 6034 stool samples from hospitalized Oman and non Oman children less than 5 years of age with moderate to severe diarrhoea were collected in 12 regional hospitals, geographically representing the whole of Oman. In this study 48.5 % (2931/6031) of the children with clinical signs of diarrhoea suffered from rotavirus associated diarrhoea. Molecular characterization was done on 450 rotavirus antigen positive samples selected on basis of local regional distribution. The main genotype combinations were G1P[8], G2P[4], and G9P[8]. G1P[8] was the dominant rotavirus in 2009 21/77 (27%), in 2011 32/66 (48.5%) and in 2012 36/65 (55.38%), whereas in 2010 and 2013 the predominant genotype was G2P[4] 13/77 (16.9%) and 23/50 (46%) respectively. Several strains exhibited unusual combinations of G and P genotypes indicating the likelihood of natural re-assortment. The unusual P[10] genotype seen in our previous study (Said et al; 2005) was not detected in the current study, however, there was an increase of G9 sequences since 2007. It is noteworthy to mention the detection of G12 for the first time in Oman. In light of the observation that the disease and economic burden on rotavirus induced diarrhoea decreased in countries which implemented rotavirus vaccination programmes, the high prevalence of rotavirus associated diarrhoea in Oman implies the introduction of rotavirus vaccination.