Protracted Outbreak of Salmonella Newport Infections Linked to Ground Beef: Possible Role of Dairy Cows - 21 States, 2016-2017

Abstract

In January 2017, CDC identified a cluster of Salmonella enterica serotype Newport infections with isolates sharing an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern, JJPX01.0010 (pattern 10), through PulseNet, the national molecular subtyping network for foodborne disease surveillance. This report summarizes the investigation by CDC, state and local health and agriculture departments, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) and discusses the possible role of dairy cows as a reservoir for strains of Salmonella that persistently cause human illness. This investigation combined epidemiologic and whole genome sequencing (WGS) data to link the outbreak to contaminated ground beef; dairy cows were hypothesized to be the ultimate source of Salmonella contamination.

FIGURE 1

Infections with the outbreak strain of Salmonella Newport (n = 106), by state of residence — 21 states, October 2016–July 2017

FIGURE 2

Isolates of the outbreak strain of Salmonella Newport from patients (n = 106), dairy cattle (n = 3), and leftover ground beef (n = 1) — 21 states, October 2016–July 2017 *The isolate collected from a dairy cow fetus in July 2016 is not displayed because cases were reported during July–October 2016 but were not investigated as part of this outbreak.