While most outbreaks of foodborne illness peak and recede, one southern Michigan restaurant struggled with an intermittent Salmonella outbreak for more than a decade.
From September 2008 to July 2019, there were 35 primary cases and one secondary case of Salmonella Mbandaka ultimately traced to the restaurant by the local public health department, William Nettleton, MD, medical director of the Kalamazoo County Health and Community Services Department, and colleagues reported in the August 20 issue of Morbidity and Mortality Weekly Report.
The unusual persistence of the outbreak was due to a complex interplay between the restaurant environment and asymptomatic food workers, Nettleton told MedPage Today.
“It was very challenging to identify the source of the outbreak,” he said in an interview. “Typically with Salmonella or other types of enteropathogens, there’s a foodborne vehicle. People get sick over a period of days to weeks, and once the source is eliminated, people stop getting sick. You get the traditional bell curve.”
“This was different,” he said. “The sporadic incidence made it very challenging.”
The restaurant initially made it on the county health department’s radar in 2012, when the Michigan Department of Health and Human Services sounded an alarm about Salmonella Mbandaka cases occurring intermittently in the county since 2008.
Kalamazoo health officials at the time launched a hypothesis-generating questionnaire, and by 2014 they’d homed their sights on the restaurant in question, after five known cases reported a meal there.