Background: Salmonella enterica subsp. enterica serovar Norwich (antigenic formula 6,7:e,h:1,6) is a serovar of the O:7 (C1) serogroup. Serovar Norwich is uncommon, with only 63 and 102 isolates recorded in the Public Health Laboratory Information System (PHLIS) for the years 1993 and 1994, respectively.

NCBI PD link for serovar Norwich: https://www.ncbi.nlm.nih.gov/pathogens/isolates/#(taxgroup_name:%22Salmonella%20enterica%22)%20AND%20computed_types:(%22serotype=Norwich%22)

Genetic characteristics: Serovar Norwich has been found to be monophyletic. Levent et al. identified a serovar Norwich strain (ST2119) in cattle feces at slaughter, which contained C63PI, SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-9, SPI-13, and SPI-14 but was missing SPI-8.

Animal reservoir: Unknown, poultry may be the potential reservoir for serovar Norwich. This serovar was also isolated from other animals such as cattle, horses, and dogs. 

Geographical distribution: According to the metadata from NCBI PD, serovar Norwich has only been reported in UK, US and Canada.  

Human outbreaks: 

Year

Location

Associated source

Number of cases

Between 2012 to 2016USChicken10
1994US: MD, PARestaurant-related7

Border rejections: There have been no recent border rejections linked to this serovar. 

Recalls: There have been no recent recalls linked to this serovar.

Relevant links:

  1. https://ajph.aphapublications.org/doi/abs/10.2105/AJPH.82.9.1273
  2. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1547190/full
  3. https://journals.asm.org/doi/10.1128/aem.00485-21?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed
  4. https://www.fsis.usda.gov/sites/default/files/media_file/documents/Risk_Profile_for_Pathogenic_Salmonella_Subtypes_in_Poultry.pdf
  5. https://www.sciencedirect.com/science/article/pii/S0362028X24001157
  6. https://pmc.ncbi.nlm.nih.gov/articles/PMC2626871/
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