Detection of sporadic cases of Norwalk-like virus (NLV) and astrovirus infection in a single Irish hospital from 1996 to 1998.

Background: 'Norwalk-like viruses' (NLV) and astroviruses are recognised as the most important etiologic agents of viral gastroenteritis, excluding rotaviruses. However, neither of these two groups of viruses is routinely screened for in Irish hospital laboratories.
Objective: The objective of this study was to examine faeces collected from patients with non-bacterial, non-rotaviral gastroenteritis and examine if NLVs and astroviruses could be identified as the causative agents of the illness.
Study Design: Faecal specimens were collected from a single Irish hospital from February 1996 to June 1998. Three hundred and sixty samples were tested for the presence of NLVs using newly designed inosine-containing degenerate primers. Two hundred and three faecal specimens from paediatric patients were screened for the presence of astroviruses.
Results: the results of the screening study were that 29 (8%) specimens were found to be positive for NLV by reverse transcription polymerase chain reaction (RT-PCR) and 15 (7%) specimens from paediatric patients were found to be positive for astroviruses. Genotyping of the NLV-positive samples determined that four of the isolates were from genotype I (G1) and 25 were G2. The G2 positive specimens were further subtyped by oligonucleotide probing and the majority (n = 21) were found to be subtype P2-B, with four isolates being typed as P2-A. No P1-B isolates were found.
Conclusions: This is the first report of detection of sporadic cases of NLV and astrovirus in Ireland. The results obtained highlight the need for continued surveillance of these viruses and the development of rapid detection systems for use in clinical laboratories.