Recurrent multistate outbreak of <i>Salmonella</i> Newport associated with tomatoes from contaminated fields, 2005

TLDR

Salmonella Newport causes over 100,000 infections annually in the United States, and outbreaks linked to tomatoes from Virginia’s eastern shore in 2002 and 2005 infected 510 and at least 72 patients, underscoring the need for improved produce safety. We performed a case‑control study during the 2005 outbreak, enrolling 29 cases and 140 matched neighbourhood controls. The study found that eating tomatoes was strongly associated with infection (matched odds ratio 9.7), tomatoes were traced to Virginia’s eastern shore where the outbreak strain was isolated from irrigation pond water, and the recurrence of the same rare strain in two multistate outbreaks two years apart indicates persistent field contamination.

Abstract

Salmonella Newport causes more than an estimated 100,000 infections annually in the United States. In 2002, tomatoes grown and packed on the eastern shore of Virginia contaminated with a pan-susceptible S. Newport strain caused illness in 510 patients in 26 states. In July-November 2005, the same strain caused illness in at least 72 patients in 16 states. We conducted a case-control study during the 2005 outbreak, enrolling 29 cases and 140 matched neighbourhood controls. Infection was associated with eating tomatoes (matched odds ratio 9.7, 95% confidence interval 3.3-34.9). Tomatoes were traced back to the eastern shore of Virginia, where the outbreak strain was isolated from pond water used to irrigate tomato fields. Two multistate outbreaks caused by one rare strain, and identification of that strain in irrigation ponds 2 years apart, suggest persistent contamination of tomato fields. Further efforts are needed to prevent produce contamination on farms and throughout the food supply chain.