Genetic diversity of noroviruses from outbreaks, sporadic cases and wastewater in Luxembourg 2008–2009

The genetic diversity of norovirus strains obtained from gastroenteritis outbreaks, sporadic case surveillance and wastewater plants was compared in Luxembourg from October 2008 until June 2009. Except for GI.6 and GIV.1 strains detected exclusively in wastewater, all other genotypes were also found in human samples. Of the nine NoV genotypes detected, only three (GII.4, GIIb/II.3 and GIIc/II.12) were associated with institutional outbreaks. The majority of sequences from all sources belonged to genotype GII.4, including two potentially new subvariants. Strains collected in the context of outbreaks may significantly under-represent the overall genetic diversity of NoVs circulating in a country.