Can a smartphone stop a norovirus outbreak?

Rebecca Trager of Chemistry World reports U.S. researchers have created a handheld detection system that is sensitive enough to catch just a few particles of norovirus.

University of Arizona biomedical engineer Jeong-Yeol Yoon and his team have created a highly sensitive portable detection system capable of spotting norovirus at levels that can make people sick. The work was presented the American Chemical Society’s national meeting in San Diego, California on 27 August.

As few as 10 norovirus particles can cause vomiting and diarrhoea in humans and the virus is extremely contagious so early detection is vital to prevent outbreaks. However, the virus does not grow in laboratory cultures and current detection methods rely on specialised and time-consuming PCR (polymerase chain reaction) techniques.

Yoon’s research team previously developed a smartphone-based device that measured light-scattering from norovirus-bound polystyrene beads in a paper microfluidic chip. It has now improved the device’s detection limit by changing to a fluorescence-based method.

‘I looked at and saw that they sell a lot of these smartphone attachments – smartphone microscope attachments – that turn your phone turns into a microscope, and by adding a couple of other components, I could convert the smartphone-based microscope into a fluorescence microscope,’ Yoon explains.

The setup uses a microscope accessory with a separate light source and two optical filters. He and colleagues also designed a 3D printed case to house the components.

To test a sample, it is first added to the paper microfluidic chip, followed by a suspension of fluorescent beads labelled with norovirus antibodies. After three to five minutes, the antibodies bind to any norovirus particles in the sample, creating aggregates of the fluorescent beads that spread out along the channels of the chip. The resulting increase in fluorescence intensity around each norovirus particle can be detected by taking a picture of the chip with the smartphone’s camera.

An app that the team has also developed then analyses the picture to calculate the sample’s norovirus concentration from the pixel count in the image. So far, the lowest detection limit corresponded to about 5 or 6 norovirus particles per sample, Yoon says. He estimates that the material costs of this system, aside from the cell phone and app development costs, are about $200.

Norovirus and Hepatitis A risk in Australian greens and berries

The apparent international rise in foodborne virus outbreaks attributed to fresh produce and the increasing importance of fresh produce in the Australian diet has led to the requirement to gather information to inform the development of risk management strategies.

A prevalence survey for norovirus (NoV) and hepatitis A virus (HAV) in fresh Australian produce (leafy greens, strawberries and blueberries) at retail was undertaken during 2013–2014 and data used to develop a risk profile. The prevalence of HAV in berries and leafy greens was estimated to be <2%, with no virus detected in produce during the yearlong survey. The prevalence of NoV in fresh strawberries and blueberries was also estimated to be <2% with no virus detected in berries, whilst for leafy greens the NoV prevalence was 2.2%.

Prevalence of a bacterial hygiene indicator, Escherichia coli, was also investigated and found to range from <1% in berries to 10.7% in leafy greens. None of the NoV positive leafy green samples tested positive for E. coli, indicating it is a poor indicator for viral risk.

The risk was evaluated using standard codex procedures and the Risk Ranger tool. Taking all data into account, including the hazard dose and severity, probability of exposure, probability of infective dose and available epidemiological data, the risk of HAV and NoV foodborne illness associated with fresh Australian berries (strawberries and blueberries) sold as packaged product was deemed to be low. The risk of foodborne illness from HAV associated with leafy greens was also deemed to be low, but higher than that for fresh berries, due mainly to the potential for recontamination post-processing if sold loose. The risk of foodborne illness from NoV associated with leafy greens was deemed to be low/moderate. Despite the prevalence of NoV in leafy greens being low and the inability to discriminate between infective and non-infective virus using PCR based methodologies, the fact that NoV was detected resulted in a higher risk associated with this pathogen-product pairing; compounded by the higher prevalence of NoV within the community compared to HAV, and the potential for leafy greens to become contaminated following processing if sold loose.

Estimating risk associated with human norovirus and hepatitis A virus in fresh Australian leafy greens and berries at retail 26 August 2019

International Journal of Food Microbiology

Valeria A.Torok, Kate R.Hodgson, Jessica Jolley, Alison Turnbull, Catherine McLeod

50 sick: Norovirus the cause of Shropshire-area hotel illness outbreak

There’s about six new Norovirus outbreaks reported every day, but I choose this one today because I have a friend who lives in Shropshire, UK.

Deborah Hardiman of the Shropshire Star writes provisional tests carried out by Public Health England have confirmed that the group who attended the Buckatree Hall Hotel near Wellington on August 7 were struck down by the sickness bug norovirus, which was unlikely to have been spread by hotel staff.

This means that the illness that causes sickness had been spread by someone carrying the viral infection.

PHE said it was “unlikely that this is a member of staff at the hotel” due to no other reports among other guests who ate the same food falling ill.

Ann Fleming, Public Health England regional spokesperson, said: “We have just received confirmation that the samples from our laboratories have tested positive for norovirus.

“No other organisms has been detected so far.

“All the food samples have tested negative.

“There are no reports of illness in guests outside of the wedding party.”

Norovirus gets around –even without vomiting

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 [1], 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 [2], 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

Journal of Hospital Infections

25 July 2019

Cheng VCC1Wong MNurs SC2Chiu KHY3Yip CCY3Wong SCY3Yuen KY4.


159 sickened: Successive norovirus outbreaks at an event center – Nebraska, October-November, 2017

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.

Article Metrics

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).


Public Health Response

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.

Norovirus sucks

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

Norovirus strains don’t all look alike

Leemor Joshua-Tor of the Howard Hughes Medical Institute writes a new structural analysis of four norovirus strains reveals that the virus’s shell varies in size and molecular arrangement – a surprise finding that could help scientists developing vaccines. 

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.

Croatia’s prime oyster farmers in alarm after norovirus discovered

I’m not sure who decided raw oysters were a food, because that gelatinous slime is gross.

Oysters are also vulnerable to norovirus.

Authorities have detected norovirus, which causes diarrhea and vomiting, in parts of the Mali Ston bay in Croatia—triggering shock and alarm among the breeders.

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?”

Some would call it knowledge.

And we’re all hosts on a viral planet.

Raw is risky: Noro sickens 180 at UK hospital because someone thought bringing raw mussels in was a good idea

This story is from Dec. 2017, but instructive.

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.

Shellfish can harbour the norovirus infection.

Rotavirus or Norovirus: They’re both spread by poo and lousy handwashing

Rotavirus is a leading cause of acute gastroenteritis (AGE) in children and is highly transmissible. In this study, we assessed the presence of AGE in household contacts (HHCs) of pediatric patients with laboratory-confirmed rotavirus.


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


Journal of the Pediatric Infectious Diseases Society,

Mary E Wikswo, Umesh D Parashar, Benjamin Lopman, et al