Annual report of the Rotavirus Surveillance Programme, 1999/2000.

The National Rotavirus Reference Centre has conducted rotavirus surveillance by means of a collaborative laboratory based initiative started in June 1999. The serotypes of rotaviruses that lead to the hospitalisation of children with acute diarrhoea were determined from June 1999 to May 2000. We examined 1126 rotavirus specimens using a combination of monoclonal antibody immunoassay, reverse transcription-polymerase chain reaction, and hybridisation. The four most common serotypes G1-G4 were represented. More than 50% of isolates tested were serotype G1, with serotype G1 being represented in most centres Australia-wide. Serotype G9 rotaviruses were identified for the first time in Australia, and were second in importance with 10% of samples tested. The significant presence of G9 viruses throughout Australia suggests the emergence of a new serotype and has implications for current rotavirus vaccine strategies that target serotypes G1-G4.