The Association between Non-foodborne Exposures and the Occurrence of Non-typhoidal Salmonellosis in Tennessee

Introduction: Salmonellosis is a growing public health problem worldwide. The estimates of non-typhoidal salmonellosis (NTS) is approximately 1.4 million/year occurs in the U.S, costing several billion dollars annually. Although the ingestion of contaminated food is considered as one of the major sources of NTS, non-foodborne and/or environmental exposures may also play major roles to transmit NTS. 

Purpose: The purpose of this study was to explore the associations between the non-foodborne (including environmental) exposures and the occurrence of NTS caused by Salmonella serotypes Newport, Javiana, and Mississippi in a FoodNet catchment area (Tennessee).

Methods: Data from FoodNet and Tennessee Department of Health comprising of 3,470 laboratory confirmed cases of NTS from 2011-2014 were used to calculate the incidence rates in Tennessee. Case-case analyses were conducted for 1,624 laboratory confirmed cases of NTS. NTS caused by serotypes Newport, Javiana, and Mississippi were considered as cases whereas the comparison group consist of with other Salmonella serotypes.

Results: After adjusting for the demographics such as age, sex, race, ethnicity, and the month and year of disease onset, NTS was found to be significantly associated with the two exposure variables (1) contact with chicken and (2) contact with pet that had diarrhea. The odds of NTS was 1.9 (95% CI: 1.10- 3.32, P=0.02) times higher for those who came in contact with chicken and 2.1 times (95% CI: 1.14- 3.90, P=0.01) higher for those who came in contact with pet that had diarrhea.

Significance: This study reveals the incidence of NTS caused by Salmonella serotypes Newport, Javiana, and Mississippi serotypes increased significantly in Tennessee. Furthermore, contact with certain types of animals is a major preventable route of transmission of NTS. In addition, continued efforts to increase awareness and practice of hand hygiene are needed to prevent the occurrence of the infection.