Australian Rotavirus Surveillance Program annual report, 2015

The Australian Rotavirus Surveillance Program, together with collaborating laboratories Australia-wide, reports the rotavirus genotypes responsible for the hospitalisation of children with acute gastroenteritis during the period 1 January to 31 December 2015. During the survey period, 1,383 faecal samples were referred for rotavirus G and P genotype analysis, and of these, 1,031 were confirmed as rotavirus positive. A total of 634 specimens had been collected from children under 5 years of age, while 397 were from older children and adults. Genotype analysis of samples from both children and adults revealed that G12P[8] was the dominant genotype in this reporting period, identified in 48.2% of strains nationally. Genotype G3P[8] was the second most common strain nationally, representing 22.8% of samples, followed by G2P[4] and G1P[8] (9% and 8% respectively). G3P[8] was further divided as equine-like G3P[8] (13.2% of all strains) and other wild-type G3P[8] (9.6%). This report highlights the continued predominance of G12P[8] strains as the major cause of disease in this population. Genotype distribution was distinct between jurisdictions using RotaTeq and Rotarix vaccines. Genotype G12P[8] was more common in states using RotaTeq, while equine-like G3P[8] and G2P[4] were more common in the states and territories using Rotarix. This survey highlights the dynamic change in rotavirus genotypes observed since vaccine introduction, including the emergence of a novel equine-like G3P[8] as a major strain. The prolonged dominance of G12P[8] for a 4th consecutive year further illustrates the unexpected trends in the wild type rotaviruses circulating in the Australian population since vaccine introduction.