Factors Associated with Sporadic Infections of Salmonella enterica Serotype Infantis, Foodborne Diseases Active Surveillance Network (FoodNet) Open Access

Sundararaman, Preethi Rajam (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/xd07gt089?locale=en


A recent increase in incidence of infections with Salmonella enterica serotype Infantis (S. Infantis) has been observed in the United States, but sporadic infections have not been well described. This study looked at Foodborne Diseases Active Surveillance Network (FoodNet) data from 2004-2014 to describe sporadic cases of infection with S. Infantis by age group, race, ethnicity, sex, season, and annual incidence. Data from a 2014 FoodNet case exposure ascertainment initiative were examined to identify foodborne, waterborne, or environmental factors associated with infection of S. Infantis. FoodNet surveillance includes 48 million persons, representing 15% of the U.S. population, from ten sites. This study employed a case-case comparison methodology, using persons with sporadic infections of Salmonella serotypes Enteritidis, Typhimurium, Newport, Javiana, or I 4,[5],12:i:- as ill controls. Because the process by which infections are reported to surveillance is non-random, traditional case-control methodology has limitations when applied to surveillance data. Case-case comparisons have been proposed as an alternative analytic method to address these limitations. During 2004-2014, a total of 1,268 sporadic laboratory-confirmed infections of S. Infantis and 42,448 sporadic laboratory-confirmed infections of other Salmonella serotypes were reported to FoodNet. Annual incidence of sporadic infections of S. Infantis in 2014 was the highest observed during the 2004-2014 period. New cases of sporadic infections of S. Infantis were most likely to occur in children less than 5 years of age, Asian persons, and persons of Hispanic ethnicity. Exposure information was available for 96 persons with infection of S. Infantis and 2,040 persons with infections of other Salmonella serotypes reported to FoodNet in 2014. In multivariable analysis adjusting for FoodNet site, season, and exposures reported by ≥10% of cases, contact with pet birds and live poultry were significantly associated with sporadic infection of S. Infantis when compared to infections of other Salmonella serotypes. Data collection is ongoing, and replicating this analysis with more years of exposure data will help validate findings. An improved understanding of factors associated with sporadic infections of S. Infantis can lead to targeted public health interventions to address the observed increase in incidence of infections in the United States.

Table of Contents

Chapter I: Literature Review. 1

Chapter II: Manuscript. 7

Introduction. 7

Methods. 9

Results. 11

Discussion. 14

References. 18

Tables. 23

Figures. 33

Chapter III: Summary, Public Health Implications, Possible Future Directions. 36

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