Norovirus outbreak report: No clarity on what made 20 people sick at Puritan event

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Noroviruses are thought to be the most common cause of acute gastroenteritis (diarrhea and vomiting illness). CDC

MANCHESTER, NH — The origin of a norovirus outbreak at the Puritan Backroom Conference and Event Center last November cannot be determined, according to an investigation conducted by the state Bureau of Infectious Disease Control (BIDC).

On Nov. 24, 2019, the Sunday before Thanksgiving, 45 people attended a private pre-holiday gathering at the center. Within 46 hours, 20 people became ill — two were waitstaff — and one person died.

U.S. Rep. Chris Pappas is part-owner of the restaurant. His staff has said since he was elected, he has stepped away from the business.

The city’s health department conducted an environmental investigation of the restaurant on Nov. 27, at the request of the New Hampshire Department of Health and Human Services (DHHS).  The Office of the Chief Medical Examiner had notified DHHS that day that norovirus had been a contributing factor in the death of an individual who attended the Puritan Backroom event.

BIDC focused on the private event because there were no other reports of illness from other groups who were at the conference center or from patrons of the restaurant that day. 

Attendees were asked to fill out a form that asked what foods they ate and what symptoms they had of a gastrointestinal illness before and after the event.

Those who attended the event were called by Manchester Health Department (MHD) staff and administered the survey.  

Stool samples were requested from ill attendees for pathogen testing and sample collection was coordinated through MHD. 

People became sick between 19 and 46 hours after the event. They ranged in age from 2 to 62, with a median age of 25; 12 were male.

Two sought healthcare but none was hospitalized.

Forty people who attended the event participated in the survey. Six cases were confirmed; 11 were found to be probable, and the survey determined 23 people didn’t experience a gastrointestinal illness.

When a comparison was made of the foods eaten by those who became ill and those who didn’t, “no statistically significant association between illness and individual food items consumed were identified,” according to the report eight-page report [see below].

As for the food preparation, that was done in the restaurant’s kitchen and then served in the adjoining conference center.  There were no critical item violations identified (i.e. violations which are known to increase the risk of foodborne illness) during the environmental assessment conducted by MHD. There were no food service workers identified as being ill at the time of the group meal. Two staff who worked the event became ill with a gastrointestinal illness on Nov. 26, two days after the event.

No one else at the conference center or at the restaurant that day reported any illness to the Puritan Backroom, MHD or DHHS.

“During outbreaks, norovirus is typically spread from person-to-person, through consumption of contaminated food or water, or by touching contaminated surfaces.  In regards to potential foodborne transmission in this outbreak, no food exposures were statistically associated with illness (i.e. no food items were identified that increased the risk of developing illness),” according to the report. 

“However, the fact that a statistically significant food item was not identified in the analysis of interview data does not exclude the possibility that food was the source of the outbreak. It is possible that multiple food items were contaminated or that a particular food item had lower levels of contamination, which could limit the ability of the investigation to identify a single common implicated food item. Low statistical power (i.e. small numbers due to the group’s size) may also impact the ability of an investigation to identify a statistically significant food item.”

No food service worker reported illness at the time of the event and no attendee reported illness in the seven days prior to the meal.

“However, the investigation relied on the information that people are able to recall and willing to share and the possibility that an ill attendee or ill food service worker introduced norovirus to the event cannot be excluded,” according to the report.

Health officials said that typically in New Hampshire there are between 50-75 norovirus outbreaks annually.  It is spread by having direct contact with an infected person, from eating or drinking contaminated food or water or touching contaminated surfaces and then putting your unwashed hands in your mouth.

NH-DHHS officials said the most common symptoms of norovirus are diarrhea, vomiting, nausea, and stomach pain. There is no specific treatment for it and most people with norovirus get better within 1 to 3 days. However, the virus can make people feel extremely ill and cause them to vomit or have diarrhea many times a day. This can lead to dehydration, especially in young children, older adults and people with other illnesses.

Read the full report below: