The Wyoming Department of Health epidemiologist Kelly Weidenbach-Vigil, MPH, published a through and well-reasoned report on the cause of the Restaurant-Associated Outbreak of Norovirus Gastroenteritis Natrona County, November – December 2012 (Download Report). The entire report is worth a read and underscores the real hazard of allowing ill employees to work. Here is a snapshot of the Report’s conclusions.
- Investigators sought to determine if the outbreak was restaurant-associated or community-acquired. Investigation findings are suggestive of a restaurant-associated outbreak.
- From December 10, 2012 through December 21, 2012, CNCHD received 187 separate foodborne illness complaints against Golden Corral. During the same time period, CNCHD received 11 complaints against various restaurants (no other restaurant was named twice). The frequency in which Golden Corral was named among both ill persons who self-identified to CNCHD and among emergency department patients was not consistent with what is normally seen during community-wide outbreaks.
- Case patient interviews did not reveal a high frequency of exposures to other risk factors. The epidemic curve (Figure 1) and the graph of visitation to Golden Corral (Figure 2) are suggestive of a common source outbreak.
- Over 95% of cases report patronizing the restaurant on or after December 7, 2012, which indicates some event occurred that allowed a large number of people to be exposed over that weekend.
- Furthermore, attack rates among parties of multiple Golden Corral patrons are high (61-73%), which is not commonly seen in community-wide outbreaks and is more common during restaurant-associated outbreaks. The environmental health findings and illness among employees (31) are also consistent with an association with the restaurant.
- Investigators were not able to determine exactly how the virus was introduced to the restaurant environment. Both patrons and employees may have played a role in the introduction and propagation of the virus in the environment.
- The presence of ill and/or previously ill employees in food-handling areas of the restaurant was possibly an important contributing factor in the propagation of this outbreak. No single food item was found to be the pathogen vehicle in this outbreak.
For more information on Norovirus, visit www.about-norwalk.com.