Epidemiology of Foodborne Disease Outbreaks Caused by Nontyphoidal Salmonella in Zhejiang Province, China, 2010–2019

Nontyphoidal Salmonella infection is a common cause of bacterial foodborne illness in Zhejiang Province, China. This study aimed to summarize the epidemiological and etiological characteristics of the outbreak of nontyphoidal Salmonella infection in Zhejiang Province. Data collected over a 10-year period (2010-2019) from the China National Foodborne Diseases Surveillance Network (NFDSN) were analyzed. A total of 78 outbreaks due to nontyphoidal Salmonella, causing 1450 illnesses and 353 hospitalizations with no deaths, were reported. The outbreak rate from May to October was about four times as high as that in other months. In addition, 33.3% (25/78) outbreaks occurred in household settings, and 41.8% (606/1450) cases were exposed at bakery product-processing factories (or shops). Moreover, food vehicles were identified in 75.6% (59/78) of Salmonella outbreaks. Of these, 30.5% (35/59) were caused by cooked meat products, followed by cold-processed cakes and sandwiches usually containing meat and/or eggs (28.81%, 17/59). Salmonella Enteritidis (56.9%, 33/78) and Salmonella Typhimurium (17.2%, 10/78) were the dominant strains. Outbreaks were most frequently attributed to cross-contamination (88.1%) and improper storage temperature (61.0%). Outbreaks caused by Salmonella are important targets for public health intervention efforts, and improving the safety and quality of cooked meat products, cold-processed cakes, and sandwiches should be a priority.