Salmonella Napoli

Background: Salmonella enterica subsp. enterica serovar Napoli (antigenic formula 1,9,12:l,z₁₃:e,n,x) is a serovar of the O:9 (D₁) serogroup.

This is a rare serovar, in the US only 19 cases were reported from 1999-2009. In other regions of the world S. Napoli is also rare, except for France, Italy, and Switzerland were it appears to have increased considerably. It was isolated from rucola and wild bird samples collected in Italy between 2004 and 2014 (Fisher et al., 2009; Mancini et al., 2014; Gori et al., 2018). Although it is a nontyphodial Salmonella strain some if its symptoms, including a prolonged incubation period (7–14 days), high fever, bacteremia, and elevated rates of hospitalizations, are similar to those caused by typhoidal Salmonella.

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

Genetic characteristics: Serovar Napoli has the typhoid-associated genes hlyE and taiA (SPI-18), cdtB, pltA, and pltB (CdtB-Islet), as well as the GICT18/1 islet.

Animal reservoir: Unknown, poultry and wild boars may be potential reservoirs for serovar Napoli. It was also isolated from wild birds but uncommonly from cattle.

Geographical distribution: Serovar Napoli has been reported in US, Canada, Australia, and Europe, mainly in UK and Italy.

Human outbreaks:

Year	Location	Associated source	Number of cases
2023	Norway	Not identified	7
2014	Italy	Ham	47
2011	Italy	Water	10
1982	England and Wales	Chocolate bars	245

Animal outbreaks:

Year	Location	Breed	Number of cases
2022-2023	Italy	Holstein Friesian	4¹

¹ The herd consisted of 310 cows. There were four animals infected: two calves and two milking cows.

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

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

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Salmonella Napoli