Norovirus is a highly contagious infectious disease, which is transmitted from person-to-person via fecal-oral, or ‘vomitus-oral’ routes, or indirectly via contaminated food or environment. Airborne transmission of norovirus was implicated in an epidemiological study during an outbreak in a hotel restaurant , but only until recently was detection of norovirus RNA demonstrated in air samples collected in patient’s room and at the nurse’s station during hospital outbreaks , presumably due to projectile vomiting of patients, flushing of toilet, or during floor cleaning as described previously.
Detection of norovirus in air samples in patient without vomiting: implication of saliva testing for norovirus in immunocompromised host
Norovirus, an extremely contagious cause of gastroenteritis, can be transmitted by infected food workers and is difficult to remove from contaminated surfaces.
What is added by this report?
An investigation into an ongoing gastrointestinal illness outbreak identified 159 persons reporting illness meeting the case definition; laboratory testing confirmed norovirus cases. Public health recommendations were not strictly followed, and transmission continued for approximately 2 weeks. Halting transmission required a coordinated approach involving thorough environmental decontamination and a strict ill employee exclusion policy.
What are the implications for public health practice?
Mitigation efforts for ongoing norovirus outbreaks in similar settings should include a comprehensive prevention strategy that addresses all possible routes of norovirus transmission.
In October 2017, the Nebraska Department of Health and Human Services (NDHHS) was notified by a local health department of a gastrointestinal illness outbreak among attendees of a wedding reception at facility A, an event center. Shortly thereafter, state and local public health officials began receiving reports of similar gastrointestinal illness among attendees of subsequent facility A events. An investigation was initiated to identify cases, establish the cause, assess possible transmission routes, and provide control recommendations. Overall, 159 cases consistent with norovirus infection (three confirmed and 156 probable) were identified among employees of facility A and attendees of nine facility A events during October 27–November 18, 2017. The investigation revealed a public vomiting episode at the facility on October 27 and at least one employee involved with preparing and serving food who returned to work <24 hours after symptom resolution, suggesting that a combination of contaminated environmental surfaces and infected food handlers likely sustained the outbreak. Recommendations regarding sanitation and excluding ill employees were communicated to facility A management. However, facility A performed minimal environmental cleaning and did not exclude ill employees. Consequently, transmission continued. To prevent persistent norovirus outbreaks in similar settings, public health officials should ensure that involved facilities implement a comprehensive prevention strategy as early as possible that includes extensive sanitation and strict exclusion of ill food handlers for at least 48 hours after symptom resolution (1).
Investigation and Results
On October 30, 2017, public health officials became aware of approximately 30 persons who developed gastrointestinal illness after attending a wedding reception (event 1) on October 27 at facility A. Norovirus was suspected based on ill attendees’ reports of developing diarrhea, vomiting, abdominal cramps, and fever approximately 12–48 hours after the event. On November 6, investigators learned of similar gastrointestinal illness among attendees at five subsequent facility A events (events 2–6), at which point an Internet-based questionnaire that assessed symptom history, events attended, and food items consumed was developed. E-mail addresses for facility A employees were provided by facility management. Investigators worked with event organizers to disseminate the questionnaire to attendees of the first six events held at facility A during the investigation period, as well as four subsequent events that were also ultimately affected by the outbreak. A case-control study was performed. A probable case was defined as the occurrence of diarrhea (≥3 loose stools within 24 hours) or vomiting and at least one other symptom (nausea, abdominal cramps, diarrhea, or vomiting) in a facility A employee or an event attendee who reported illness onset 6–72 hours after attending a facility A event on or after October 27. Confirmed cases met the probable case definition and had norovirus RNA detected in a stool specimen by real-time reverse transcription–polymerase chain reaction (RT-PCR) (2). Controls were identified as facility A employees who were not ill and were exposed to facility A during the study period or event attendees who were not ill and attended an event during the study period. Estimated attack rates (ARs) were calculated per event, using host-estimated number of attendees as denominators.
Ten events that included food service provided by facility A were held at the facility during October 27–November 18, 2017. Overall, 378 persons from nine events completed questionnaires, including 18 of 25 (72%) employees and 360 of 1,383 (26%) event attendees (Table). Only one questionnaire response among 70 attendees was received for the tenth event and was thus excluded from analysis. Overall, 159 persons (six employees and 153 event attendees) reported illness meeting the probable (156) or confirmed (three) case definition (Figure); 186 controls were identified. Comparison of food items consumed by case-patients and controls was limited because the only items available at all nine events were water, ice, and drink garnishes; however, no item was significantly associated with illness. Estimated ARs for the first six events, which occurred before any public health intervention, ranged from 7% to 35% per event (median = 18.5%) (Table).
The investigation uncovered a witnessed episode of vomiting in a public area near the event space by an event attendee. The episode occurred at the beginning of the October 27 event (event 1) on carpeting in the lobby at the entrance to the event hall and might have represented the initial introduction of norovirus into facility A. Although no testing of environmental surfaces was conducted to confirm, it is possible this vomiting contaminated environmental surfaces.
On November 7, investigators learned that the carpeting where vomiting occurred on October 27 had been swept with a vacuum cleaner and inadequately sanitized; the agent used did not have efficacy against norovirus. Investigators recommended sanitizing environmental surfaces with a sodium hypochlorite (chlorine bleach) solution or a disinfectant specifically registered by the Environmental Protection Agency (EPA) as effective against norovirus*,† and excluding ill employees from work until ≥48 hours after symptom resolution (1). However, cases of gastroenteritis occurred at two events that were held on November 10 (event 7) and 11 (event 8) after these recommendations were made; estimated ARs at event 7 and event 8 were 4% (six of 150 attendees) and 15% (53 of 360 attendees), respectively, indicating ongoing transmission. Investigators subsequently learned of an employee who left work when she became ill at 10:00 a.m. on November 7, with nausea, vomiting, fever, headache, and myalgias, and returned to work preparing and serving food on November 8, <24 hours later.
Stool specimens from three ill persons were tested. Norovirus genogroup II was detected by real-time RT-PCR from all three stool specimens tested; further genetic sequencing by Nebraska Public Health Laboratory and CDC confirmed that all three specimens yielded the same norovirus genotype, GII.P12-GII.3. Two of the case-patients in whom norovirus was laboratory-confirmed attended the October 27 event (event 1), and the third attended the event on November 11 (event 8).
After initial public health recommendations to use disinfectants registered by the EPA and exclude ill employees failed to halt transmission (1), several discussions were held with facility A management during the period leading up to a planned event on November 18 (event 9). The recommendation for strict employee exclusion was reiterated on November 15, along with ideas for minimizing pressures on employees to work while ill, such as offering paid sick leave and bringing in staff members from a different location to work the event. Consideration was given to postponing the upcoming event or finding an alternative location for it. Facility A hired a professional cleaning service experienced with norovirus eradication to sanitize the facility on November 16 and 17. After thorough sanitation and strict employee exclusion were implemented, the event held on November 18 (event 9) had an estimated AR of 1% (three of 350 attendees), indicating reduced transmission (Table). No further illnesses in facility A employees or event attendees were reported to public health officials.
Norovirus, the most common cause of outbreak-associated acute gastroenteritis worldwide, is highly efficient at causing human disease (3). The virus is extremely contagious, with a low infectious dose capable of causing infection with as few as 18–2,800 virus particles (4,5). In addition, large numbers of virus can be shed by infected persons, even those with asymptomatic infections (1). Norovirus is resistant to many common commercial disinfectants and is able to persist on environmental surfaces for up to 2 weeks (6).
Transmission occurs through several different routes, and multiple transmission routes can coexist during norovirus outbreaks (6,7). In addition to foodborne and direct person-to-person spread, transmission can also occur through ingestion of aerosolized particles and through contact with contaminated environmental surfaces, which are believed to harbor the virus and play a role in sustaining outbreaks (8,9). Multiple outbreaks caused by foodborne sources and subsequently perpetuated by environmental contamination or person-to-person spread have been described (7,10). In addition, when contaminated food items are implicated in outbreaks, infected food handlers are often involved (1).
In this setting of successive outbreaks at the same event center, norovirus was likely transmitted through a combination of persistently contaminated environmental surfaces and ill food handlers (7). The investigation findings indicate that the initial public vomiting episode likely contaminated the carpeting at the entrance to the event hall. Inadequate sanitizing of the area and aerosolization of the virus resulting from subsequent vacuuming could both have led to further spread. Although no environmental testing was done, investigators suspect that widespread environmental contamination was likely present (9). Transmission was halted only after the facility was thoroughly cleaned and a strict ill employee exclusion policy was enforced.
The findings in this report are subject to at least two limitations. First, because the total number of attendees at each facility A event was not known, investigators had to rely on host estimations. Accordingly, calculation of exact ARs was precluded. Similarly, questionnaire distribution to individual attendees was facilitated by each event’s host. As a result, investigators had no way of knowing how many attendees successfully received the invitation to complete the Internet-based questionnaire, and accuracy of corresponding AR calculations might have been affected. Because methodology for calculating ARs was consistent across all events, the potential of adversely affecting comparison of event-specific ARs was likely limited. However, the limitation was believed to introduce enough bias to preclude a cohort analysis. Second, environmental sampling that might have helped elucidate possible transmission routes was not done. By the time public health officials learned of the outbreak’s ongoing nature, 10 days had passed since the initial public vomiting episode. Because results of environmental testing would not have changed the recommendation for extensive sanitation, such testing was not prioritized.
Mitigation efforts for ongoing norovirus outbreaks in similar settings should include a comprehensive prevention strategy that attempts to address all possible routes of norovirus transmission. In this setting, control measures that included extensive environmental decontamination and strict exclusion of all ill food handlers for ≥48 hours after symptom resolution were needed to halt the outbreak. Public health officials can also verify that facilities involved in similar persistent outbreaks are implementing recommended public health interventions.
Introduction Norovirus outbreaks frequently occur in communities and institutional settings acquiring a particular significance in armed forces where prompt reporting is critical. Here we describe the epidemiological, clinical and laboratorial investigation of a multicentre gastroenteritis outbreak that was detected simultaneously in three Portuguese army units with a common food supplier, Lisbon region, between 5 and 6 December 2017.
Methods Questionnaires were distributed to all soldiers stationed in the three affected army units, and stool specimens were collected from soldiers with acute gastrointestinal illness. Stool specimens were tested for common enteropathogenic bacteria by standard methods and screened for a panel of enteric viruses using a multiplex real-time PCR assay. Food samples were also collected for microbiological analysis. Positive stool specimens for norovirus were further genotyped.
Results The three simultaneous acute gastroenteritis outbreaks affected a 31 (3.5%) soldiers from a total of 874 stationed at the three units and lasted for 2 days. No secondary cases were reported. Stool specimens (N=11) were negative for all studied enteropathogenic agents but tested positive for norovirus. The recombinant norovirus GII.P16-GII.4 Sydney was identified in all positive samples with 100% identity.
Conclusions The results are suggestive of a common source of infection plausibly related to the food supplying chain. Although centralisation of food supplying in the army has economic advantages, it may contribute to the multifocal occurrence of outbreaks. A rapid intervention is key in the mitigation of outbreak consequences and in reducing secondary transmission.
Simultaneous norovirus outbreak in three Portuguese bases in the Lisbon region, December 2017
Journal of the Royal Army Medical Corps
António Lopes-João1, J R Mesquita2,3, R de Sousa4, M Oleastro4, C Penha-Gonçalves1and M S J Nascimento3,5
The discovery, reported June 10, 2019, in the journal Proceedings of the National Academy of Sciences, overturns nearly two decades of conventional wisdom about norovirus. Until now, the only structural data about the virus that scientists had came from a single, not particularly prevalent, strain.
“Everyone thought that all the strains would look about the same – like the one that was solved 20 years ago,” says Howard Hughes Medical Institute Investigator Leemor Joshua-Tor. “It turns out that they don’t!”
Joshua-Tor’s team used a microscopy technique called cryo-electron microscopy (cryo-EM) to visualize the shells of four viral strains, including one responsible for up to roughly 80 percent of norovirus outbreaks. That strain was 71 percent larger (by volume) than the one previously reported. Its shell was also decorated with a different pattern of molecular spikes.
Those structural details will be crucial for scientists working on vaccines or antiviral therapies to treat norovirus infection, says Joshua-Tor, a structural biologist at Cold Spring Harbor Laboratory (CSHL). Though norovirus causes about 21 million cases of foodborne illness in the United States every year, there are currently no approved therapies.
At least one vaccine candidate is working its way through clinical trials now. But CSHL study coauthor James Jung says scientists will need to take the virus’s newfound variation into account – so any new vaccine protects against a broad array of strains.
The traditional oyster-tasting feast in March has been canceled and fears are mounting of huge financial losses to the local community that harvests about 3 million oysters each year.
Experts are pointing their fingers at the outdated sewage system in the area that has seen a rise in the numbers of tourists flocking to Croatia’s stunning Adriatic coast.
“I am really sorry but people themselves are to blame that something like this happened,” explained Vlado Onofri from the Institute for Marine and Coastal Research in nearby Dubrovnik. “It’s something that has to be solved in the future.”
While some stomach bugs can be eliminated with cooking, norovirus survives at relatively high temperatures.
Navigating the oyster fields in their small boats, the farmers proudly show visitors rows and rows of oyster-filled underwater farm beds spreading through the bay.
Top municipal official Vedran Antunica questioned the assumption that the local sewage system was to blame for the outbreak.
“Viruses are everywhere, now as we speak, the air is full of viruses,” Antunica said. “We had the same sewage system in the past, so why wasn’t it (norovirus) recorded? What has changed?”
Do not bring raw anything into a hospital full of immunocompromised people (those NZ mussels are cooked).
And I’m still looking at you, Brisbane Private Hospital, for continuing to serve raw sprouts on everything.
The Bailiwick Express reports that an outbreak of the winter vomiting bug (we call it Norovirus) which forced hospital bosses to ban visitors from wards was caused by someone bringing mussels in for a patient, it has emerged.
Over Christmas, Northumbria Healthcare NHS Trust will partially lift the restriction on visitors, introduced after norovirus spread across a number of sites.
Officials have traced its spread to a visitor bringing in mussels for an inpatient at Wansbeck General Hospital in Ashington, Northumberland.
It is thought to have affected at least 180 people.
Between December 2011 and June 2016, children aged 14 days to 11 years with AGE were enrolled at 1 of 7 hospitals or emergency departments as part of the New Vaccine Surveillance Network. Parental interviews, medical and vaccination records, and stool specimens were collected at enrollment. Stool was tested for rotavirus by an enzyme immunoassay and confirmed by real-time or conventional reverse transcription-polymerase chain reaction assay or repeated enzyme immunoassay. Follow-up telephone interviews were conducted to assess AGE in HHCs the week after the enrolled child’s illness. A mixed-effects multivariate model was used to calculate odds ratios.
Overall, 829 rotavirus-positive subjects and 8858 rotavirus-negative subjects were enrolled. Households of rotavirus-positive subjects were more likely to report AGE illness in ≥1 HHC than were rotavirus-negative households (35% vs 20%, respectively; P < .0001). A total of 466 (16%) HHCs of rotavirus-positive subjects reported AGE illness. Of the 466 ill HHCs, 107 (23%) sought healthcare; 6 (6%) of these encounters resulted in hospitalization. HHCs who were <5 years old (odds ratio, 2.2 [P = .004]) were more likely to report AGE illness than those in other age groups. In addition, 144 households reported out-of-pocket expenses (median, $20; range, $2–$640) necessary to care for an ill HHC.
Rotavirus-associated AGE in children can lead to significant disease burden in HHCs, especially in children aged <5 years. Prevention of pediatric rotavirus illness, notably through vaccination, can prevent additional illnesses in HHCs.
Evidence for household transmission of rotavirus in the United States, 2011-2016
Stool tests performed on those who are ill haven’t confirmed this diagnosis, but Director of Health Services Dr. Goldstein said that norovirus is “likely” the culprit of the students’ symptoms, which include vomiting, diarrhea and stomach pain. Resident Advisors on campus have reported 103 cases of students having contracted the debilitating stomach bug as of Wednesday evening, according to Goldstein, Director of Health Services.
Goldstein first notified the campus community about the virus in a campus-wide email sent Monday, Feb. 4 at 2:40 p.m., but didn’t name the illness as norovirus at that time.
Some students, however, felt this email did not come soon enough. Haley Matthes ‘19 voiced her frustrations and warned students to be aware of its spreading in a post in the Lafayette College Class of 2019 Facebook group on Feb. 2.
“I’m just tired of the school waiting for a campus-wide sickness to escalate to a point where they need to send out a bulletin [or] cancel classes,” Matthes said in a follow-up email.
Matthes was also upset that extended hours weren’t offered at Bailey Health Center.
Several students in the Phi Kappa Psi fraternity have also had the virus. According to Mikey Burke ‘21, approximately 12 to 15 members of the fraternity had contracted the virus as of Tuesday, although he said he expected that number to grow.
“I think it just spread really quickly throughout the house, it originated there and spread to a lot of the brotherhood, I live in McKeen and only hung out at the [Phi Psi] house for a couple hours…and got sick,” Burke said in an email.
Bobby Longo ‘21, another Phi Psi fraternity member to have the virus, said he believed the email warning on Monday was “too late.”
“Norovirus is an extremely contagious stomach virus that spreads like wildfire. After the first or second case on campus we should have been notified… it ramps up as people go from class to class spreading it,” Longo said in an email.
According to Goldstein, his level of concern about the virus was raised when the health center began receiving phone calls and emails from concerned students and parents, as the health center was “not overwhelmed” by the number of students coming to Bailey about the virus.
Goldstein said he wanted to find a “sweet spot” of not raising a level of hysteria but also communicating with the students. He decided to send the campus-wide email more based on “the feedback from students,” Goldstein said.
“I think what’s happening is students are self-treating and getting through this without needing to see a provider, but the numbers are pretty significant on campus. The students communicating with me was a good thing,” he said.
According to Goldstein, reports from Resident Advisors and Bailey total a little over 150, but Goldstein said there may be overlap among these reports, if for example, a student both went to Bailey and reported their illness to their RA.
While Goldstein said that the discussion of the school closing “hasn’t happened yet,” he believes certain social gatherings will be cancelled if the virus continues spreading rapidly. One event, the Lunar New Year dumpling making party hosted by ISA and ACA, was cancelled on Tuesday as a result of the spreading sickness.
Abstract Published research on outbreaks of gastrointestinal illness has focused primarily on the results of epidemiological and clinical data collected postoutbreak; little research has been done on actual preventative practices during an outbreak. In this study, the authors observed student compliance with hand hygiene recommendations at the height of a suspected norovirus outbreak in a university residence in Ontario, Canada. Data on observed practices was compared to post-outbreak self-report surveys administered to students to examine their beliefs and perceptions about hand hygiene. Observed compliance with prescribed hand hygiene recommendations occurred 17.4% of the time. Despite knowledge of hand hygiene protocols and low compliance, 83.0% of students indicated that they practiced correct hand hygiene during the outbreak. To proactively prepare for future outbreaks, a current and thorough crisis communications and management strategy, targeted at a university student audience and supplemented with proper hand washing tools, should be enacted by residence administration.
To acquire data on contamination with Norovirus in berry fruit and salad vegetables in the United Kingdom, 1,152 samples of fresh produce sold at retail in the UK were analysed for Norovirus.
Of 568 samples of lettuce, 30 (5.3%) were Norovirus-positive. Most (24/30) lettuce samples which tested positive for Norovirus were grown in the UK and 19 of those 24 samples contained NoV GI. Seven/310 (2.3%) samples of fresh raspberries were Norovirus-positive. Most (6/7) of the positively-testing fresh raspberry samples were imported, but no predominance of a genogroup, or any seasonality, was observed. Ten/274 (3.6%) samples of frozen raspberries were Norovirus-positive. The country of origin of the positively-testing frozen raspberry samples was not identified in most (7/10) instances.
The collected data add to the currently limited body of prevalence information on Norovirus in fresh produce, and indicate the need for implementation of effective food safety management of foodborne viruses.
Norovirus in produce sold at retail in the United Kingdom
Cook, N., Williams, L., & Dagostino, M. (2019). Prevalence of . Food Microbiology, 79, 85-89. doi:10.1016/j.fm.2018.12.003