Astrovirus and Norovirus Infection in a Paediatric Setting

Abstract

Astrovirus and norovirus are RNA viruses that cause gastroenteritis in children. In Australia, the role these viruses play in children with diarrhoea presenting to a paediatric hospital have not been examined since rotavirus vaccination was introduced in 2007. This study aimed to determine the prevalence and nature of infections at one of the largest paediatric teaching hospitals in Australia, and to compare the performance of commercial ELISA tests with nested reverse transcription-polymerase chain reaction assays (nRT-PCR) developed in our laboratory. Faecal specimens received January 2009 to December 2010 from children presenting with diarrheal symptoms were tested. Over 5,000 specimens were tested for viral antigens by the ELISA method with incidences of 0.5% for astrovirus and 6.6% for norovirus. Compared to the nRT-PCR assays, the astrovirus ELISA had a sensitivity of 77.4% (95% CI= 58.9-90.4%) and specificity of 100% (95% CI=97.5-100.0%) and the norovirus sensitivity was 93.3% (95% CI= 90.2-95.75) with a specificity of 94.2% (95% CI= 85.8-98.4%). The estimated incidences if all study specimens were tested by both ELISA and nRT-PCR were 5.1% (95% CI= 4.53-5.77%) for astrovirus and 30.9% (95% CI= 29.63-32.19%) for norovirus. Astovirus genotypes HAstV-1 to 4 were detected with HAstV-1a the predominant genotype and 12 norovirus genotypes were detected: NoV GI.1, GI.2, GI.4, GI.6, GI.13, GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13 with GII.4 the predominant genotype. In 2009, the epidemic GII.4 2008 variant was dominant and this was replaced by the pandemic GII.4 New Orleans variant in 2010. The impact of the rotavirus vaccination program is difficult to assess from this two year study period as although astrovirus activity was low, norovirus activity was high due to the pandemic GII.4 New Orleans variant. Further studies will be required, both in Australia and worldwide, to assess the effect of the rotavirus vaccines on astrovirus and norovirus infection.