Study Salmonella Infections in Norway shedding duration
Background   Non-typhoidal salmonellae (NT-Salmonella) are a major cause of diarrhoea worldwide. Salmonella is generally transmitted through the faecal-oral route. Commonly, this occurs through the improper handling of contaminated foods but also zoonotically.?NT-Salmonella gastroenteritis is usually self-limited and generally resolves within 48 to 72 hours. However, in some cases the initial infection can lead to a carrier state in humans, which corresponds to a persistent colonization of the gut and continuous long-term shedding of Salmonella. This study aimed?to investigate?host and pathogen-specific risk factors?associated with?long-term?shedding?of?NT-Salmonella?post-infection in human salmonellosis cases in Norway,?to?inform infection control and preventive measures.   ?   Methods   All salmonellosis?cases?reported to the national surveillance system in?2019?were invited?to participate in the?study.?Participants?were asked to submit?a stool sample and a questionnaire?five?weeks post-initial positive sample.?We?cultured?all samples?and sequenced?isolates?to identify genotype (cgMLST), serotype and antimicrobial resistance.?We analysed data by?descriptive statistics and measured association for two?levels of?shedding;?i) Long term shedding (LTS): positive sample?at?= 5 weeks after initial sample, and = 5 allelic differences compared to the initial sample (cgMLST), and?ii) Short term shedding (STS): negative sample at?= 5 weeks after initial sample.??      Results   The study included data from 273?participants. 23.4%?were classified as LTS, and?70.7% as STS.?Stratification by serotype?found that 45% of S.?Agbeni isolates were LTS. In contrast, only?21% of the S. Typhimurium and 19% of S. enteritidis were LTS.?We identified a positive association between the length of shedding?and?persisting diarrhoea?(p.?0.02)?5 weeks?after initial sample, age group 18-?46 (p. 0.02) and lactose-free diet (p. 0.03).?