Norovirus gastroenteritis outbreak with a secretor-independent susceptibility pattern, Sweden

Abstract

Norovirus (NoV) is recognized as the commonest cause of acute gastroenteritis among adults. Susceptibility to disease has been associated with histo-blood group antigens and secretor status; nonsecretors are almost completely resistant to disease. We report a foodborne outbreak of GI.3 NoV gastroenteritis that affected 33/83 (40%) persons. Symptomatic disease was as likely to develop in nonsecretors as in secretors (odds ratio [OR] 1.41, 95% confidence interval [CI] 0.46-4.36 vs. OR 0.71, 95% CI 0.23-2.18, p = 0.57). Moreover, no statistical difference in susceptibility was found between persons of different Lewis or ABO phenotypes. The capsid gene of the outbreak strain shares high amino acid homology with the Kashiwa645 GI.3 strain, previously shown to recognize nonsecretor saliva, as well as synthetic Lewis a. This norovirus outbreak affected persons regardless of secretor status or Lewis or ABO phenotypes.

Figure 1

Time to onset of symptoms after patient exposure to norovirus-contaminated food (n = 30), Sweden. Zero indicates the time point for serving and ingesting the contaminated food.

Figure 2

Phylogenetic analysis of amino acids of the norovirus capsid gene from the gastroenteritis outbreak in Jönköping, Sweden (JKPG, •) and reference strains. The tree was constructed using the neighbor-joining and Poisson correction methods, with MEGA 4.0 software (www.megasoftware.net). Bootstrap values are shown at the branch nodes (values <70% are not shown). Reference sequences were collected from Genbank and represent the 8 genotypes of GI as described by Zheng et al. (26). Scale bar indicates nucleotide substitutions per site. NV-USA [M87661], Aich124-JPN [AB031013], SOV-GBR [L07418], C59-USA [AF435807], HLL219-USA [AF414403], Stav-Nor [AF145709], LR316-USA [AF414405], VA115-USA [AY038598], Kashiwa645-JAP [BD011871], PD196-DEU [AF439267], JKPG-SWE [FJ711163] DSV-USA [U04469], Chiba-JPN [AB042808], Valetta-MLT [AJ277616], Musgrove-GBR [AJ277614], SzUG1-JPN [AB039774], Hesse-DEU [AF093797], Wiscon-USA [AY502008], Wnchest-GBR [AJ277609], Boxer-USA [AF538679].