Australian Rotavirus Surveillance Program: Annual report, 2009/2010

The Australian Rotavirus Surveillance Program together with 15 collaborating laboratories Australia-wide conducts a laboratory based rotavirus surveillance program. This report describes the genotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2009 to 30 June 2010, the 3rd year of surveillance following introduction of rotavirus vaccines into the National Immunisation Program. Seven hundred and seventy-eight faecal samples were referred to the centre for G and P genotype analysis using hemi-nested multiplex reverse transcription-polymerase chain reaction. Of the 422 confirmed as rotavirus positive, genotype G1P[8] was the dominant type nationally, representing 49.3%, followed by genotype G2P[4] (21.1%). Genotypes G3P[8], G4P[8] and G9P[8] each represented less than 3% of circulating strains nationally. The dominance of G1P[8] was in part associated with a large outbreak of severe gastroenteritis in the Northern Territory in 2010. The identification of uncommon rotavirus genotype combinations has increased since vaccine introduction, with G1P[4], G2P[8] and G9P[4] identified during this survey. Single strains of G1P[6] and G4P[6] were identified during this study period. This survey continues to highlight the fluctuations in rotavirus genotypes, and results from this survey suggest there is limited genotype selection based on vaccine usage. However, the large G1P[8] outbreak of gastroenteritis in the Northern Territory may have resulted from vaccine pressure on wild-type strains.