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Background: Salmonella enterica subsp. enterica enterica serovar Rissen (antigenic formula 6,7,14:f,g:-) is a serovar of the O:7 (C1) serogroup. This serovar was first isolated from HOST in LOCATION in YEAR. Serovar Rissen is the XXth most common nontyphoidal Salmonella serotype Salmonella serotypes in the United States.first nomenclating by Rohde & Tiedje during early 1960s. In Japan, Kaneko reported the first isolate of S. Rissen from patients with sporadic diarrhea was found during the period from April 1985 to December 1994 in Yamanashi Prefecture. Recently, serovar Rissen is the 4th most common nontyphoidal Salmonella serovar isolated from human infections in LOCATION and is also among the top 20 most frequently reported Thailand.

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

Genetic characteristics: Serovar Rissen has been found to be polyphyletic with three lineages identified and one stand-alone singleton that does not cluster with any other Salmonella Rissen isolates. Serovar Rissen ST469 has been found worldwide, in countries such as Thailand, China, and Italy. This sequence type is the most common ST for serovar Rissen. ST8877 has been isolated from a cracked table egg in Sudan.

Pornsukarom et al. reported that all Thai Rissen isolates in their study were multidrug-resistant and more than 90% were resistant to ampicillin, sulfisoxazole, tetracycline and streptomycin. Conversely, half of the Salmonella Rissen isolates in the USA were pan-sensitive while some were resistant to only tetracycline. Wang et al. observed that Salmonella Rissen human isolates (anal swabs or feces) had the common resistance profile: ampicillin, trimethoprim-sulfamethoxazole, and tetracycline; resistance were conferred by bla_TEM, tetA, and sul3, respectively. A study from India reported on multidrug-resistant Salmonella Rissen strains (resistant to nalidixic acid, sulfamethizole, and carbanicillin) isolated from seafood in Cochin, India. Moreover, Spanish Salmonella Rissen isolated from live mussels carried mcr-1 gene and other antimicrobial resistance genes (aac(6')-Iaa, aadA1, aadA2, bla_TEM-1B, cmlA1, sul1, sul3, tet(A), and dfrA1).

Animal reservoir: Swine is the major animal reservoir of serovar Rissen, including the pork production chain. However, Salmonella Rissen can be also detected in seafoods.

Geographical distribution: Serotype Rissen has been reported especially in Asian countries such as Thailand, Vietnam, China, Japan, and VietnamIndia, but it has also been found in Italy, France, Spain.

Human outbreaks: XX Two outbreaks linked to to Salmonella Rissen have been associated with SOURCESfood. Some examples are shown below.

Year	Location	Associated source	Number of cases
2022	Europe: multi-country	Cucumbers	72
2011	US: multistate	Imported Papayas from Mexico	106
2008	US: multistate	Rice & Wheat Puff Cereal	28
2008	Europe: multi-country	Meat	119
2004	France	Infant formula	141
2002	Germany	Tea, aniseed herbal	42
2020	France	Fuet from Spain	18
2008-2009	US: multistate	White pepper	87	1998	US: multistate	Toasted Oats Cereal	209

Border rejections: Multiple border rejections associated with serovar Rissen have been reported. Here we selected NUMBER five as examples.

Year	Exporting country	Importing country	Associated source	Product category
2024	Poland	Italy	Turkey meat	Poultry meat and poultry meat products
2022	China	Sweden	Organic soybean cake	Feed materials
	Denmark	Finland	Rapeseed expellers	Feed materials
2022	Spain	Belgium	Turkey processed animal protein¹	Feed materials
2022	Ukraine	Germany	Sunflower cake	Feed materials
2020	Spain	Switzerland	Chorizo sausage	Meat and meat products (other than poultry)
2020	Belgium	Austria	Dog feed²	Pet food

¹ Salmonella Rissen and Muenster were found.

² Salmonella Rissen and monophasic Typhimurium were found.

Recalls: Recalls: Multiple recalls associated with serovar Rissen have been reported. Here we selected NUMBER as examples.

2017Infant formula

Year	Location	Recalled food	Type
2020	France
Fuet¹	Food
2019	Ultra-processed food	1998	US: multistate	Toasted Oats Cereal Pig ears²	Ready-to-Eat foodPet treats

¹ This This recall was caused by an outbreak of Salmonella enterica serovar Agona associated with infant formula products manufactured by the Lactalis Nutrition Santé group in France.by France to withdraw all fuet with all dates and bearing the mark ES-10.12147/B-CE carried out in various stores across France.

² This recall was caused by an a multistate human outbreak of Salmonella serovar Agona infections linked to toasted oats cereal manufactured by Malt-O-Meal. linked to several Salmonella serovars, including Rissen, linked to pig ears treats for dogs.

Relevant links:1.