The Loudoun County Health Department has identified more than 135 individuals who reported becoming ill after visiting the Chipotle Mexican Grill at 21031 Tripleseven Road, Sterling, VA 20165 between July 13 and 16, 2017. “Two ill patrons have tested positive for the same strain of norovirus. Based on symptoms reported and these preliminary laboratory results, the cause of the outbreak is believed to be norovirus, though the specific source of the norovirus has not yet been identified,” said Dr. David Goodfriend, director of the Health Department. “The Health Department is not aware of any customers becoming ill since the reopening of the facility last Wednesday.”

According to the Centers for Disease Control and Prevention (CDC), 1 in 6 Americans gets sick from contaminated food each year. Norovirus (sometimes called “stomach flu”) is the most common cause of foodborne illness. People infected with norovirus usually develop symptoms 12 to 48 hours after being exposed to norovirus and most people who are ill get better within one to three days. Frequent hand washing and staying home when sick are two of the most important means of preventing the spread of infection.

The public is encouraged to contact the Loudoun County Health Department at health@loudoun.gov with any questions or concerns.

And, then there is this:

I give credit to the scientists for having a bit of ironic humor in an article recently published about one of the foods I do avoid.  I could never recall if it was the months with or without an “r” that you were supposed to avoid eating raw oysters.  Now, I guess it really does not matter if the water they were grown in contain human feces.

BC oysters and norovirus: Hundreds of cases in months with an “r”

British Columbia Medical Journal, Vol. 59, No. 6, July, August 2017, page(s) 326,327 BC Centre for Disease Control
Lorraine McIntyre, MSc, Eleni Galanis, MD, MPH, FRCPC, Natalie Prystajecky, PhD, Tom Kosatsky, MD

Between November 2016 and March 2017 more than 400 individuals across Canada developed norovirus gastroenteritis associated with the consumption of BC oysters. Over 100 cases occurred mid-November in participants at a Tofino oyster festival. Six cases occurred in persons attending a December oyster barbecue in Victoria. By March over 300 additional cases of norovirus linked to cultivated BC oysters harvested from multiple sites on both the east and west coasts of Vancouver Island were identified in BC, Alberta, and Ontario consumers.

Norovirus is a highly infectious cause of gastroenteritis typically spread from person to person and is associated with regular community outbreaks in schools, hospitals, day cares, and care facilities. Foodborne outbreaks of norovirus are often linked to ill food handlers. In this recent outbreak, oysters were contaminated in the marine environment where they were farmed. The trace-back of oysters consumed by infected individuals led to the closure of 13 geographically dispersed marine farms in BC (see map) and to extensive public outreach.

Genotypic analysis of norovirus isolated from the cases included several variants of genogroup I (GI) early in the outbreak and both genogroups GI and GII later in the outbreak.

Both GI and GII norovirus were detected in oysters from shellfish farms. This suggests that oysters bind and act as a reservoir for community outbreak strains and disseminate those strains to consumers.[1]

Although sewage is often the cause of oyster contamination it remains unclear whether one or many sewage sources contributed to the contamination of shellfish farms. The 2016–17 outbreak was preceded by a wet fall and accompanied an unseasonably cold winter. Wet, cold, and dark winters enhance norovirus survival, allowing for longer retention in ocean sediments and in oysters.[2,3] The infective dose of norovirus is estimated as few as 18 particles.[2] Given the low infective dose and the viability of norovirus in cold water, we postulate that sewage spread by ocean currents may have contaminated geographically dispersed farms. Among potential sources under investigation are sewer overflows, metropolitan and local wastewater treatment plants, municipal raw sewage discharge, and commercial fishing vessels. The BCCDC is leading a collaborative group reviewing pollution sources discharging to BC marine environments that may have contaminated BC oysters.

In this outbreak, both raw and cooked oysters led to illness; oysters were likely insufficiently cooked to inactivate norovirus. In addition to norovirus, pathogens like Vibrio sp., Salmonella sp., and hepatitis A can be transmitted to oyster consumers; cooking oysters to an internal temperature of 90 °C for at least 90 seconds will reduce this risk. The “rule” that shellfish is safe to eat in months with an “r” (September to April) is false. First, bacteria and viruses persist in cold seawater. Second, marine biotoxins (saxitoxin and domoic acid that cause paralytic and amnesic shellfish poisoning) occur year round.

Physicians and laboratories play an important role in controlling foodborne disease. In this outbreak, trace-back of oysters linked to cases was used to close shellfish farms. If you see patients with acute gastroenteritis who recently consumed shellfish, inform your local public health office and submit stool samples for testing.[4]

The authors acknowledge partners in the national outbreak investigation and the environmental transmission of norovirus working group.

1. Rajko-Nenow P, Waters A, Keaveney S, et al. Norovirus genotypes present in oysters and in effluent from a wastewater treatment plant during the seasonal peak of infections in Ireland in 2010. Appl Environ Microbiol 2013;79: 2578-2587.
2. Campos CJA, Lees DN. Environmental transmission of human noroviruses in shellfish waters. Appl Environ Microbiol 2014;80:3552-3561.
3. Hassard F, Gwyther CL, Farkas K, et al. Abundance and distribution of enteric bacteria and viruses in coastal and estuarine sediments—a review. Front Microbiol 2016;(7):Article 1692.
4. Guidelines and Protocols Advisory Committee. Infectious diarrhea – guideline for ordering stool specimens. Accessed 18 March 2017. www2.gov.bc.ca/gov/content/health/practitioner-professional-resources/bc-guidelines/infectious-diarrhea.

Heath officials have determined the source of a norovirus that sickened dozens of people attending a festival at the Northern Wisconsin State Fairgrounds last month.

Wisconsin Department of Health Services spokeswoman Jennifer Miller told the Leader-Telegram the gastroenteritis outbreak at the Special Kids Day event was caused by contaminated food.

Miller says multiple stool samples collected from those who became sick indicated that the illness was caused by food and wasn’t passed through physical contact. She says the specific contaminated food source remains under investigation.

Symptoms of the sickness include vomiting, diarrhea, low-grade fever and fatigue. There isn’t a cure for norovirus but people have generally recovered within a few days.

Following reports of norovirus-like illnesses in people who report eating raw oysters from several areas in Washington and elsewhere, public health officials at the Washington State Department of Health have tracked down areas where some of the illness-linked oysters were harvested.  Over the past several weeks, small harvest closures and recalls have been ordered, the largest of which is in Hammersley Inlet in Mason County, where a recall has been issued for any shellfish harvested there since March 15. Smaller portions of the shellfish harvesting area were closed and shellfish recalled on March 2, April 4 and April 5.

The three-mile stretch of commercial shellfish growing beds is about two-thirds of the Hammersley Inlet growing area and is harvested by 31 shellfish companies. Shellfish harvested from the area is typically shipped to many states and countries. Shellfish growers and the Department of Health are working with local health jurisdictions and other states to track down all harvested product to make sure it is not available to be consumed.

“We are actively evaluating all potential pollution sources in the area to determine what is causing the contamination.  The area will remain closed until we can assure that public health is protected,” said Rick Porso, Director of the Office of Environmental Health and Safety. “This issue underscores the importance of protecting our marine water, especially in areas where shellfish are grown.”

Norovirus is a common stomach virus that spreads easily. It can be transmitted through contaminated food or surfaces and person-to-person contact. The source of norovirus is people — specifically, the feces and vomit of infected individuals.  The virus can be present in marine water indirectly through boat discharges, failing septic systems, malfunctioning wastewater treatment plants, or directly from an infected person. Because shellfish are filter feeders, they can concentrate the virus and infect individual that consume them raw or undercooked.

Norovirus symptoms include watery diarrhea, vomiting and stomach pain. Most people get better within two days. Dehydration can be a problem among some people, especially the very young, the elderly, and people with other illnesses. For those consumers concerned about the increased risk of illness, ordering and eating cooked shellfish is an effective way to prevent norovirus illness.

Food Safety News reported that the consumption of raw or undercooked oysters from British Columbia is blamed for 321 cases of norovirus gastroenteritis in three Canadian provinces, according to an updated report from the Public Health Agency of Canada (PHAC), released March 27. The outbreak, which has affected residents of British Columbia, Alberta and Ontario, began in December 2016 and is on-going.

As of March 28’s update, 321 clinical cases of gastroenteritis linked to oysters had been reported between Dec. 4, 2016, and March 18, this year: 223 in British Columbia, 42 in Alberta and 56 in Ontario.

According to a spokesperson from the Canadian Food Inspection Agency (CFIA), seven shellfish aquaculture sites have been temporarily closed by the Department of Fisheries and Oceans. The closures are based on sample results and/or epidemiological assessments. Investigation is on-going into other harvest areas that have been linked to illnesses.

Seattle-King County Public Health is investigating a series of illnesses associated with consumption of oysters harvested along the Washington coast. Between Jan.  10 and March 20, as many as 39 people may have become ill after eating raw oysters at one of several different restaurants or private events in the county.

No laboratory confirmation is available; however, these symptoms are ‘suggestive’ of norovirus, according to a March 28 news release issued by the health department. While oysters served at the retail locations were harvested from various areas along the Washington coast, one small part of Samish Bay accounted for 22 illnesses linked to four servings. A section of the Samish Bay growing area was closed on March 17 for all species.