HPA Norovirus Update

Norovirus – Credit HPA

 

# 6817

 

The UK’s HPA has released a new update on their busy norovirus season, which has prompted headlines in British papers announcing more than One Million Cases this year.

 

That number is an extrapolation, based on the assumption that there are 288 uncounted cases for every case officially diagnosed.

 

So take it as an estimate, not a precise count.  Still, reported cases of norovirus are well ahead of last year’s numbers across the UK.

 

 

HPA update on seasonal norovirus activity: 2 January 2013

2 January 2013

Latest figures from the Health Protection Agency (HPA) show there have been 3,877 laboratory confirmed cases of norovirus this season (from week 27 to week 51 2012). The latest figures are 72 per cent higher than the number of cases reported at this point last year, when there were 2,255 cases.

 

During the Christmas period there is typically a drop in the number of laboratory reports. In previous norovirus seasons the general trend is that cases increase in the New Year and we expect to see cases rise again over the next few weeks.

 

During the two weeks up to 30 December there were 29 hospital outbreaks reported, compared to 70 in the previous fortnight, bringing the total of outbreaks for the season to 590.

 

Cases of norovirus have risen earlier than expected this winter season and this is a trend that has been seen across Europe and other parts of the world. It has not yet been determined why this has been the case and activity varies significantly from year to year.

 

John Harris, an expert in norovirus from the HPA said: “As we have seen in previous years there has been a dip in the number of confirmed laboratory reports owing to the Christmas and New Year period. However, in line with other norovirus seasons we will expect to see an increase in the number of laboratory reports in the next few weeks.

 

“Norovirus is very contagious, and anyone who has had it knows it is very unpleasant. If you think you may have the illness then it is important to maintain good hand hygiene to help prevent it spreading. We also advise that people stay away from hospitals, schools and care homes as these environments are particularly prone to outbreaks.”

 

Norovirus can be transmitted by contact with contaminated surfaces or objects, by contact with an infected person, or by the consumption of contaminated food or water. Symptoms of norovirus include a sudden onset of vomiting and/or diarrhoea. Some people may have a temperature, headache and stomach cramps. The illness usually resolves in one or two days and there are no long-term effects.

Ends

Notes to editors

1. Indications from Europe and Japan are that norovirus activity also started to increase early. In Australia the norovirus season also peaks during the winter but this season it has gone on longer than usual and they are seeing cases into their summer. The HPA is following up with colleagues internationally.
2. The number of laboratory confirmed cases represents just a fraction of the actual amount of norovirus activity as it is estimated that for each confirmed case, there are a further 288 unreported cases, as the vast majority of those affected do not seek healthcare services in response to their illness. Data from The Infectious Intestinal Diseases II (IID II) report can be found at the Food Standards Agency website [external link].

(Continue . . . )

 

 

For more on noroviruses, you may wish to revisit the following blogs.

 

Vomiting Larry And His Aerosolized Norovirus

An Unwanted Lagniappe From The Kitchen

UK: Norovirus Season Starts Early

»» Read More

Vomiting Larry And His Aerosolized Norovirus

Credit UK’s Health & Safety Laboratory

 

# 6812

 

Sounding vaguely like an invention lifted from one the Tom Swift books of my youth (e.g. Tom Swift and His Atomic Earth Blaster, Tom Swift and His Electric Rifle), Vomiting Larry is a dummy that . . . well, vomits.

 
All in the name of science, of course.

 

In order to test how well (and how far) Norovirus (aka `The Winter Vomiting Bug’) can spread through the air, scientists have created a dummy that spews. A move, I suspect, prompted primarily by a lack of willing  human volunteers for this study.

  

By adding a florescent dye marker to Larry’s `vomitus’, researchers at the UK’s Health & Safety Laboratory have determined that droplets – too small to be readily seen – can end up as far as 3 meters away from the source.

 

Vomiting Larry featured on the BBC website

Winter Vomiting bug has been very much in the news of late due to the recent major outbreaks of norovirus, which causes this illness. A recent article on the BBC news website has highlighted the work that the Health and Safety Laboratory has done to establish the extent with which the surrounding environment becomes contaminated when an individual vomits.

 

This is an important consideration for infection control during outbreaks of norovirus where the key symptom is projectile (forced) vomiting. Catherine Makison of HSL's Occupational Hygiene Unit has developed a humanoid simulated vomiting system affectionately known as "Vomiting Larry".

 

"Larry" was primed with a vomitus substitute (to which a fluorescent marker was added so as to identify even small splashes post vomiting), and simulated vomiting was carried out. As the BBC video shows graphically, these tests demonstrated the full extent of room contamination post vomiting and that small droplets can spread over three metres from the "Larry" system, which are not easily visible under standard white hospital lighting.

 

HSL studies have shown that Norovirus can be isolated from these small droplets at concentrations capable of causing an infection. This information might highlight why this robust and highly infectious virus is transmitted between people so readily.

 

The outcomes of these studies have contributed to reviews of healthcare guidance in hospitals and are due to be published in relevant journals in the near future.

 

The role of direct aerosolized human-to-human transmission of norovirus remains less than clear, although there are numerous anecdotal reports that suggest that it happens.

 

The CDC – in a an MMWR report from 2011 called Updated Norovirus Outbreak Management and Disease Prevention Guidelines describes transmission thusly:

 

Transmission

Norovirus is extremely contagious, with an estimated infectious dose as low as 18 viral particles (41), suggesting that approximately 5 billion infectious doses might be contained in each gram of feces during peak shedding. Humans are the only known reservoir for human norovirus infections, and transmission occurs by three general routes: person-to-person, foodborne, and waterborne.

 

Person-to-person transmission might occur directly through the fecal-oral route, by ingestion of aerosolized vomitus, or by indirect exposure via fomites or contaminated environmental surfaces.

 

 

And last May, in Norovirus: The Gift That Keeps On Giving, we looked at an incident involving a girl’s soccer team where 17 girls were exposed via a reusable grocery bag, likely contaminated from an airborne route.

 

 

While one of the keys to prevention is good hand hygiene, unlike with many other bacteria and viruses, alcohol gel doesn’t do a particularly good job of killing the virus (see CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus).

 

Which makes a good old fashion hand scrubbing with soap and water the best preventative.

 

As new studies that show the aerosolized spread of noroviruses are published, hospital infection control policies may need to revisit the use of facemasks for HCWs caring for infected patients.

»» Read More

An Unwanted Lagniappe From The Kitchen

 

Norovirus – Credit CDC PHIL 

Lagniappe – A little something extra given to a customer. 

# 6766

 

 

The CDC estimates that norovirus (aka the `Winter Vomiting Bug’ or less accurately, `Stomach Flu’) causes more than 20 million cases of gastroenteritis each year in the United States. Anyone who has endured it can attest that a bout with norovirus is misery incarnate.

 

The CDC maintains an extensive Norovirus webpage where they describe the illness, how it is spread, and how to avoid infection. Among known causes of foodborne illness, norovirus is the largest culprit.

 

 

The CDC’s NOROVIRUS: FOR FOOD HANDLERS page warns:

 

The virus can easily contaminate food because it is very tiny and infective. It only takes a very small amount of virus particles (fewer than 100) to make someone sick.

 

Food can get contaminated with norovirus when:

• infected people who have stool or vomit on their hands touch the food,
• it is placed on counters or surfaces that have infectious stool or vomit on them, or
• tiny drops of vomit from an infected person spray through the air and land on the food.

 

All of which makes the thorough cleaning of plates and utensils used in restaurants a priority. 

According to a PLoS One  study, published yesterday, the prescribed methods of cleaning these items in restaurants does a good job against common bacteria – like Escherichia coli K-12 and Listeria innocua – but not so well in sanitizing against norovirus.

 

The open access study is called:

 

Efficacies of Sodium Hypochlorite and Quaternary Ammonium Sanitizers for Reduction of Norovirus and Selected Bacteria during Ware-Washing Operations

Lizanel Feliciano, Jianrong Li^*, Jaesung Lee, Melvin A. Pascall^*

 

Abstract

Cross-contamination of ready-to-eat (RTE) foods with pathogens on contaminated tableware and food preparation utensils is an important factor associated with foodborne illnesses. To prevent this, restaurants and food service establishments are required to achieve a minimum microbial reduction of 5 logs from these surfaces.

 

This study evaluated the sanitization efficacies of ware-washing protocols (manual and mechanical) used in restaurants to clean tableware items. Ceramic plates, drinking glasses and stainless steel forks were used as the food contact surfaces. These were contaminated with cream cheese and reduced-fat milk inoculated with murine norovirus (MNV-1), Escherichia coli K-12 and Listeria innocua.

 

The sanitizing solutions tested were sodium hypochlorite (chlorine), quaternary ammonium (QAC) and tap water (control). During the study, the survivability and response to the experimental conditions of the bacterial species was compared with that of MNV-1.

 

The results showed that current ware-washing protocols used to remove bacteria from tableware items were not sufficient to achieve a 5 log reduction in MNV-1 titer. After washing, a maximum of 3 log reduction in the virus were obtained. It was concluded that MNV-1 appeared to be more resistant to both the washing process and the sanitizers when compared with E. coli K-12 and L. innocua.

(Continue . . . )

 

Essentially, these researchers took silverware, ceramic plates, and glassware – inoculated them with norovirus, E. coli, and Listeria – and ran them through standard dishwasher or hand washing protocols with either a bleach solution or quaternary ammonium compound (QAC) solution.

 

After that, they tested them for residual pathogens.

 

Although commercial dishwashers did a better job than did handwashing, with both, significant contamination from the norovirus remained behind.

 

The authors write:

 

Conclusions

From the results of our study, it could be concluded that QAC and sodium hypochlorite sanitizers normally used to inactivate bacteria in manual and mechanical ware-washing operations were unable to produce the same level of virus inactivation under similar conditions, irrespective of the nature of the tableware item tested.

Further studies are needed to develop more effective ware-washing protocols for the removal of viruses from food contact surfaces/tableware items. Also, the combination of different detergents and sanitizing solutions (especially those containing surfactant agents) should be evaluated since they may help to enhance the removal and inactivation of non-enveloped viruses.

 

 

Obviously, people who are sick should not be handling food, but people can shed the virus even after they stop showing symptoms.

 

So one of the keys to prevention is good hand hygiene.

Unfortunately, unlike with many other bacteria and viruses, alcohol gel doesn’t do a particularly good job of killing the virus, something we discussed last year in  CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus.

 

Which makes a good old fashion hand scrubbing with soap and water the best preventative.

 

The CDC recommends the following steps to protect yourself from the virus.

 

And of course, the obvious question is . . .if norovirus escapes routine dishwashing protocols, what about other viruses like Hepatitis A and influenza?

Reportedly, these researchers will be looking at those viruses next.

»» Read More

UK: Norovirus Season Starts Early

80% of Norovirus Outbreaks occur between November & April - Credit CDC 

 

# 6710

 

 

Whether you call it Norwalk or Norovirus – the more descriptive `Winter Vomiting Bug’, or the less accurate `stomach flu’  - the virus behind millions of cases of gastroenteritis each year can pack more misery into 72 hours than should be allowed by law.

 

Long the scourge of crowded institutions - like nursing homes, cruise ships, hospitals and schools - the virus also circulates readily in the community, taking advantage of low levels of human immunity and its ease of spread.

 

After exposure and a short incubation period (12-24 hours), the victim usually experiences nausea, frequent vomiting & diarrhea, and stomach pain – and may also experience headache, fever, and body aches.

 

The illness generally runs its course in 1 to 3 (very long) days, and most people recover.

 

But among those who are aged or infirmed, the virus can take a heavy toll. According to the CDC, each year the norovirus:

 

• causes about 21 million cases of acute gastroenteritis (inflammation of the stomach or intestines or both)
• contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and the elderly

 

Last month in JAMA, a study of 407 norovirus outbreaks across 308 nursing homes showed an 11% increase in fatalities during times when a facility was experiencing an outbreak.

 

JAMA. 2012 Oct 24;308(16):1668-75.

Hospitalizations and mortality associated with norovirus outbreaks in nursing homes, 2009-2010.

Trivedi TK, DeSalvo T, Lee L, Palumbo A, Moll M, Curns A, Hall AJ, Patel M, Parashar UD, Lopman BA.

 

A short (2 minute) video on this paper may be viewed below. Among their recommendations, it is important to identify an outbreak early, take preventative measures, and nursing staff who become infected should not return to work until at least 48 hours after their symptoms have abated.

 

 

 

Already this winter, I’m aware of a couple of outbreaks here in Central Florida, and in the post-hurricane Sandy recovery, we’ve media reports that Viral outbreak at Hurricane Sandy evacuation shelter shuts 3 Brooklyn schools.

 

And from the UK today,  reports that their `winter vomiting bug season’ has gotten off to an early start.

 

Stomach flu earlier, worse in Britain

Published: Nov. 11, 2012 at 12:35 AM

LONDON, Nov. 11 (UPI) -- Norovirus, or the stomach flu, is 27 percent higher in Britain than at the same time last year and six weeks earlier than usual, health officials say.

(Continue . . .)

 

Earlier this week, the HPA posted the following notice on their Syndromic Surveillance site, indicating reports of vomiting were elevated, suggesting `community-based norovirus activity’.

 

 

One of the keys to prevention is good hand hygiene.

 

Unfortunately, unlike with many other bacteria and viruses, alcohol gel doesn’t do a particularly good job of killing the virus, as we discussed last year in  CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus.

 

Which makes a good old fashion hand scrubbing with soap and water the best preventative.

 

The primary method of infection is via the fecal-oral route. The CDC describes it this way:

 

Norovirus and Food

Norovirus is a leading cause of disease from contaminated foods in the United States. Foods that are most commonly involved in foodborne norovirus outbreaks include leafy greens (such as lettuce), fresh fruits, and shellfish (such as oysters). However, any food item that is served raw or handled after being cooked can become contaminated with noroviruses.

Norovirus Spreads Quickly

Norovirus can spread quickly from person to person in crowded, closed places like long-term care facilities, daycare centers, schools, hotels, and cruise ships. Noroviruses can also be a major cause of gastroenteritis in restaurants and catered-meal settings if contaminated food is served.

 

The viruses are found in the vomit and stool of infected people. You can get it by

• Eating food or drinking liquids that are contaminated with norovirus (someone gets stool or vomit on their hands, then touches food or drink).
• Touching surfaces or objects contaminated with norovirus and then putting your hand or fingers in your mouth.
• Having direct contact with a person who is infected with norovirus (for example, when caring for someone with norovirus or sharing foods or eating utensils with them).

People with norovirus illness are contagious from the moment they begin feeling sick until at least 3 days after they recover. But, some people may be contagious for even longer.

 

The role of direct aerosolized human-to-human transmission of norovirus remains a bit murky, although there are numerous anecdotal reports that suggest that it happens.

 

The CDC – in a an MMWR report from 2011 called Updated Norovirus Outbreak Management and Disease Prevention Guidelines describes transmission thusly:

 

Transmission

Norovirus is extremely contagious, with an estimated infectious dose as low as 18 viral particles (41), suggesting that approximately 5 billion infectious doses might be contained in each gram of feces during peak shedding. Humans are the only known reservoir for human norovirus infections, and transmission occurs by three general routes: person-to-person, foodborne, and waterborne.

 

Person-to-person transmission might occur directly through the fecal-oral route, by ingestion of aerosolized vomitus, or by indirect exposure via fomites or contaminated environmental surfaces.

 

The CDC recommends the following steps to protect yourself from the virus.

 

 

 

Good advice, but frankly - having already gone through at least one memorable bout with the virus - if I found myself caring for someone with Norovirus in my household, I’d take a few extra precautionary steps.

 

According to:

 

GUIDELINE FOR THE PREVENTION AND CONTROL OF NOROVIRUS GASTROENTERITIS OUTBREAKS IN HEALTHCARE SETTINGS

Taranisia MacCannell, PhD, MSc ; Craig A. Umscheid, MD, MSCE ; Rajender K. Agarwal, MD, MPH ; Ingi Lee, MD, MSCE ; Gretchen Kuntz, MSW, MSLIS ;Kurt B. Stevenson, MD, MPH 3 and the Healthcare Infection Control Practices Advisory Committee (HICPAC)

(EXCERPT)

PERSONAL PROTECTIVE EQUIPMENT

23. If norovirus infection is suspected, adherence to PPE use according to Contact and Standard Precautions is recommended for individuals entering the patient care area (i.e., gowns and gloves upon entry) to reduce the likelihood of exposure to infectious vomitus or fecal material.    (Category IB) (Key Question 1.C.4)

  
24. Use a surgical or procedure mask and eye protection or a full face shield if there is an anticipated risk of splashes to the face during the care of patients, particularly among those who are vomiting. (Category IB) (Key Question 3.C.2.a) 

25. More research is needed to evaluate the utility of implementing Universal Gloving (e.g., routine use of gloves for all patient care) during norovirus outbreaks. (No recommendation/unresolved issue) 

 

One of the reasons I keep a generous supply of exam gloves, and surgical (& N95) masks in my emergency kit. 

 

And finally, earlier this year in Norovirus Sequelae we looked at  a new study appearing in Clinical Infectious Diseases that found a link between norovirus infection and ongoing gastrointestinal complaints.

 

Researchers looked at the records of more than 1700 military personnel who were treated for AGE (acute gastroenteritis) during three known norovirus outbreaks.

 

By comparing them to controls, they determined that those with a history of AGE were at increased risk of developing chronic gastrointestinal disorders.

 

Since this was a fairly small study, and some variability was detected in outcomes across the three outbreaks studied, more research will be needed to confirm their findings and to determine how long these after effects may persist.

 

Still, this is one virus that you want to avoid catching, if at all possible.

»» Read More

Norovirus Sequelae

 

 

# 6404

 

 

Last month I wrote a blog called Norovirus: The Gift That Keeps On Giving, about an outbreak of this nasty gastrointestinal malady among a group of teenage girls at a soccer tournament in 2010.  

 

It now appears that the above title may have been more appropriate than I imagined, as a new study appearing in Clinical Infectious Diseases finds a link between norovirus infection and ongoing gastrointestinal complaints.

 

According to the CDC norovirus sickens more than 20 million Americans every year, hospitalizes up to 70,000, and contribute to 800 deaths.  The CDC maintains an extensive Norovirus webpage where they describe the illness, how it is spread, and how to avoid infection.

 

 

As if enduring 24 to 48 hours of vomiting and diarrhea wasn’t enough, today’s study suggests that those who experience a norovirus infection are at substantially greater risk of developing chronic dyspepsia, constipation and GERD (Gastroesophageal reflux disease).

 

In the following study researchers looked at the records of more than 1700 military personnel who were treated for AGE (acute gastroenteritis) during three known norovirus outbreaks. 

 

By comparing them to controls, they determined that those with a history of AGE were at increased risk of developing chronic gastrointestinal disorders.

 

Since this was a fairly small study, and some variability was detected in outcomes across the three outbreaks studied, more research will be needed to confirm their findings and to determine how long these after effects may persist.

 

 

 

Post-infectious gastrointestinal disorders following norovirus outbreaks

Chad K. Porter1, Dennis J. Faix, Danny Shiau, Jennifer Espiritu, Benjamin J. Espinosa, and Mark S. Riddle

Results. We identified 1,718 subjects from three outbreaks. After controlling for important demographic covariates, the incidence of constipation, dyspepsia and GERD was approximately 1.5 fold higher (p<0.01) in AGE exposed subjects than matched subjects. We also noted variability in outcome incidence across outbreaks.

Conclusions. It appears that the risk of dyspepsia, constipation and GERD are higher among those who have AGE during a confirmed norovirus outbreak. While these findings need confirmation, they suggest that dysmotility may result subsequent to these infections. If confirmed, the costs and morbidity associated with the chronic consequences of norovirus should be considered.

Dysmotility is a generic medical term to describe diseases of the GI tract (esophagus, stomach, small and large intestines) where the muscles do not function properly.

 

The primary route of infection is the fecal-oral route (although there is evidence it can also be airborne), and the best intervention is . . . you guessed it . . .  washing your hands.

 

Unfortunately, unlike with many other bacteria and viruses, alcohol gel doesn’t do a particularly good job of killing the virus, as we discussed last year in  CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus.

 

For more information, the CDC’s hand hygiene website provides many useful resources, including a link to a new iPad/iPhone application called iScrub.

 

»» Read More

Norovirus: The Gift That Keeps On Giving

 

 

 

# 6319

 

 

The hallmark of a Norovirus infection is that during the first 12 hours of vomiting and diarrhea you are afraid you might die, and during the second 12 hours you begin to fear you won’t.

 

While the vast majority afflicted recover, among the elderly and frail this illness can induce serious dehydration and on rare occasions can be fatal.

 

According to the CDC, each year the norovirus:

 

• causes about 21 million cases of acute gastroenteritis (inflammation of the stomach or intestines or both)
• contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and the elderly

 

 

The CDC maintains an extensive Norovirus webpage where they describe the illness, how it is spread, and how to avoid infection. Among known causes of foodborne illness, norovirus is the largest culprit.

 

Source CDC

 

From the Journal of Infectious Diseases today we’ve an epidemiological investigation that examined a norovirus outbreak among a girl’s soccer team and found a common denominator (a reusable grocery bag) and evidence suggestive of aerosol contamination.

 

In today’s IDSA journal report (and accompanying commentary) we get a fascinating look what may be the `perfect human pathogen’, and how it was easily spread among 17 girls at a soccer tournament in 2010.

 

First, the press release, then the study:

Public release date: 9-May-2012

Investigators trace of role reusable grocery bag in norovirus outbreak

Oregon investigators recently mapped the trail of an outbreak of a nasty stomach bug among participants in a girls' soccer tournament to a reusable open top grocery bag stored in a hotel bathroom. Their findings, which illustrate the role that inanimate objects can play in spreading norovirus infection, appear in The Journal of Infectious Diseases.

 

Noroviruses are a leading cause of gastroenteritis worldwide and the most common cause of foodborne outbreaks in the United States. Highly contagious, even in low concentrations, the viruses spread efficiently from feces and vomit by direct contact or by indirect transmission from viral contamination of surfaces. In October 2010, a cluster of gastroenteritis that appeared in a group of people with no apparent direct physical contact with a pathogen challenged investigators to find the cause and take appropriate control measures.

 

In the study, Kimberly K. Repp, PhD, MPH, of Oregon Health and Sciences University, and William E. Keene, PhD, MPH, of the Oregon Public Health Division in Portland, investigated an outbreak in a group of 17 Oregon girls, 13-14 years old, and their four adult chaperones attending a soccer tournament in Washington state. All had traveled in private automobiles, shared hotel rooms, and eaten at local restaurants. Eight cases were identified, including the index patient who was presumably infected prior to the trip. There was no direct contact between the original patient and her teammates after her symptoms began; before her overt symptoms began she left her room and moved in with a chaperone. The girl subsequently began vomiting and having diarrhea in the chaperone's bathroom. The outbreak affecting the rest of the team began several days later; they were exposed by handling a bag of snacks that unfortunately had been stored in the hotel bathroom. Virus aerosolized within the bathroom likely settled onto the grocery bag and its contents. Matching viruses were found on the reusable shopping bag two weeks later.

(Continue . . . )

 

A Point-Source Norovirus Outbreak Caused by Exposure to Fomites

1. Kimberly K. Repp1, and William E. Keene2

The authors describe the route of infection by saying:

 

Aerosolization of vomit and feces has been demonstrated to be of major importance in norovirus outbreaks [13]. Even viruses aerosolized from flushing a toilet can contaminate surfaces throughout a bathroom [14]. Once a fomes is contaminated, transfer to hands and other animate objects can readily occur [15]. The more confined the space (eg, most bathrooms), the more intense would be the “fallout” [13].

 

The authors also take notice of some of the lesser known hazards of reusable grocery bags (see my earlier blog It’s In The Bag).

 

Accompanying this research letter is an informative editorial by Aron J. Hall called:

 

Noroviruses: The Perfect Human Pathogens?

1. Aron J. Hall

 

 

The role of direct aerosolized human-to-human transmission of norovirus remains a bit murky, although there are numerous anecdotal reports that suggest that it happens.

 

The CDC – in a an MMWR report from 2011 called Updated Norovirus Outbreak Management and Disease Prevention Guidelines describes transmission thusly:

 

Transmission

Norovirus is extremely contagious, with an estimated infectious dose as low as 18 viral particles (41), suggesting that approximately 5 billion infectious doses might be contained in each gram of feces during peak shedding. Humans are the only known reservoir for human norovirus infections, and transmission occurs by three general routes: person-to-person, foodborne, and waterborne.

Person-to-person transmission might occur directly through the fecal-oral route, by ingestion of aerosolized vomitus, or by indirect exposure via fomites or contaminated environmental surfaces.

»» Read More

CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus

 

 

Photo Credit – CDC

 

# 5747

 

While dispensers of alcohol-based hand sanitizers have become ubiquitous in many health care facilities over the past few years, there remain serious questions over just how effective they may be in killing some particularly hearty pathogens.

 

In recent years it has become apparent that alcohol based hand cleansers are not effective at killing the spores of the Clostridium difficile bacteria, and so the CDC offers this advice:

 

How can Clostridium difficile infection be prevented in hospitals and other healthcare settings?

• Use gloves when entering patients’ rooms and during patient care.
• Perform Hand Hygiene after removing gloves.
• Because alcohol does not kill Clostridium difficile  spores, use of soap and water is more efficacious than alcohol-based hand rubs. However, early experimental data suggest that, even using soap and water, the removal of C. diffile spores is more challenging than the removal or inactivation of other common pathogens.
• Preventing contamination of the hands via glove use remains the cornerstone for preventing Clostridium difficile transmission via the hands of healthcare workers; any theoretical benefit from instituting soap and water must be balanced against the potential for decreased compliance resulting from a more complex hand hygiene message.

 

And more recently, we’ve seen increased evidence that these handy hand sanitizers may be `suboptimal’ at killing some nonenveloped viruses (including norovirus), as well.

 

In March of this year, the CDC’s MMWR published a lengthy report that called into question the efficacy of alcohol based products against norovirus:

 

Updated Norovirus Outbreak Management and Disease Prevention Guidelines

(Excerpt)

Overall, studies suggest that proper hand washing with soap and running water for at least 20 seconds is the most effective way to reduce norovirus contamination on the hands, whereas hand sanitizers might serve as an effective adjunct in between proper handwashings but should not be considered a substitute for soap and water handwashing.

 

Today, the CMAJ has an early release news item that summarizes the findings of a couple of recent studies that showed that health care facilities that relied more heavily on alcohol-based sanitizers were more apt to experience outbreaks of norovirus.

 

 

Hand sanitizers may increase norovirus risk

August 10, 2011

 

Alcohol-based hand sanitizers may not be the panacea for hand hygiene they were once supposed, as mounting research indicates they may not be effective substitutes for soap and water, and in some cases may actually increase the risk for outbreaks of highly contagious viruses in health care settings.

 

Public health experts, however, say more rigorous investigations will be necessary to trump the convenience of using hand sanitizers, among other benefits, or substantially alter existing recommendations that strongly encourage their use by health care professionals.

(Continue . . . )

 

You can read the abstract to one of these studies in the May 2011 edition of the  AJIC.

 

Use of alcohol-based hand sanitizers as a risk factor for norovirus outbreaks in long-term care facilities in northern New England: December 2006 to March 2007

 

David D. Blaney, MD, MPH , Elizabeth R. Daly, MPH , Kathryn B. Kirkland, MD ,Jon Eric Tongren, PhD, MSPH , Patsy Tassler Kelso, PhD , Elizabeth A. Talbot, MD

 

Lead author Dr. David Blaney of CDC’s  Epidemic Intelligence Service is quoted in the CMAJ article as saying that alcohol-based hand sanitizers might be, “suboptimal in controlling the spread of noroviruses.”

 

For now, the efficacy of alcohol based hand sanitizers against norovirus remains controversial at best. More, and better studies will be needed before any firm conclusions can be drawn.

 

None of this is to suggest that hand sanitizers are without value.

 

They are fast and easy - which promotes their frequent use - and when used properly they appear effective against a wide variety of bacteria and enveloped viruses, including colds and influenzas.

 

 

But when dealing with a norovirus outbreak, for now the best policy appears to be washing your hands thoroughly with soap and water.

»» Read More

Hand Hygiene Isn’t Just For Flu

 

 

 

# 4402

 

 

Last summer and fall many people adopted – at least temporarily – increased hand washing (and alcohol sanitation) as a preventative against the H1N1 `swine’ flu.

 

Hand hygiene was widely promoted by the CDC, and other public health venues, as something everyone could do to reduce their chance of getting sick.

 

As a compulsive hand-washer (a trait I picked up as a paramedic back in the 1970s, a time before we routinely wore latex gloves!), my habits didn’t really change, although I probably used the alcohol gel more often when I was away from home.

 

But for many people this habit, unlike the germs on their hands, didn’t stick.

 

With the swine flu threat widely perceived as diminishing, people don’t seem to be quite as diligent about hand hygiene as they were a few months ago.  

A pity, because good hand hygiene can prevent a lot of illnesses.

 

New England Journal of Medicine

 

Maryn McKenna had a great blog more than a year ago (see This is what hand hygiene looks like), utilizing the above graphic.  The petri dish on the left depicts MRSA bacteria from a health care worker’s hand. 

The blank culture on the right is what you get after using alcohol foam sanitizer.   

 

Good hand hygiene matters.

 

In recent weeks we’ve heard of a rise in Norovirus outbreaks (see Norovirus: The Gift That Keeps On Giving) around the country. 

 

The primary route of infection is the fecal-oral route (although it can also be airborne), and the best intervention is . . . you guessed it . . .  washing your hands.

 

Unfortunately, unlike with many other bacteria and viruses, alcohol gel doesn’t do a particularly good job of killing the norovirus.  

 

(Note: Norwalk and Norovirus both refer to the same RNA virus (family Caliciviridae) that that are responsible for numerous outbreaks of non-bacterial gastroenteritis around the world.)

 

    Appl Environ Microbiol. 2010 Jan;76(2):394-9. Epub 2009 Nov 20.

Effectiveness of liquid soap and hand sanitizer against Norwalk virus on contaminated hands.

 

Liu P, Yuen Y, Hsiao HM, Jaykus LA, Moe C.

(EXCERPTS)

The purpose of this study was to screen sodium hypochlorite and ethanol for efficacy against Norwalk virus (NV) and expand the studies to evaluate the efficacy of antibacterial liquid soap and alcohol-based hand sanitizer for the inactivation of NV on human finger pads.

 

. . . sodium hypochlorite concentrations of >or=160 ppm effectively eliminated RT-qPCR detection signal, while ethanol, regardless of concentration, was relatively ineffective . . .

 

Despite the promise of alcohol-based sanitizers for the control of pathogen transmission, they may be relatively ineffective against the HuNoV, reinforcing the need to develop and evaluate new products against this important group of viruses.

 

When dealing with Norovirus, hand washing with soap and water is clearly the way to go.

 

While the effectiveness of hand washing against what is presumed to be a mostly-airborne/large droplet vectored virus like influenza is debatable, good hand hygiene can prevent a lot of other illnesses.    

 

Pandemic or not, it is always a healthy habit to keep.

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Norovirus: The Gift That Keeps On Giving

 

 

# 4370

 

 

If you’ve ever been stricken by Norovirus then you know that for the first 12 hours you are afraid you may die, and for the second 12 hours you are terrified that you won’t.

 

Known in the UK as the Winter Vomiting virus, Norwalk-like (genus Norovirus, family Caliciviridae) viruses are part of a family of single strand RNA viruses that cause  acute gastroenteritis in humans.

 

They are infamous for spreading rapidly through cruise ships, hotels, hospitals, schools and long-term care facilities.  While the symptoms may be dramatic and miserable (vomiting, diarrhea, stomach pains, etc), it generally runs its course in 24-48 hours, rarely resulting in death.

 

Immunity to the virus is generally short-lived and incomplete, and reinfection several times over a person’s lifetime is common.  Some people appear more prone to infection than others, with the virus having a greater affinity for blood type O.

 

For reasons that are less than clear, Norovirus outbreaks exhibit high seasonality, occurring most often in the winter months. 

 

Which brings us to an interesting article today from the CanWest News service that may shed some light on this mystery.   No firm conclusions, mind you.  But an interesting theory . . .

 

 

Virus may incubate in icy lakes: researchers; Norwalk affects millions annually

Monday, February 22nd, 2010 | 12:41 am

Canwest News Service

Norwalk virus, a gut-wrenching fixture of Canadian winters whose source and seasonal nature have long been a mystery, may originate in drinking water drawn from lakes whose cool winter temperatures keep the microbe nicely preserved, suggests a new study.

 

University of Toronto researchers, comparing Norwalk outbreaks to river water flow and lake temperatures, theorize that a near-endless "feedback loop" sends the virus from human waste to surface waters, then to water treatment plants that are unable to eliminate the bug, and finally back into household faucets.

 

The theory, if proven, raises the question of whether tap water should be treated with ultraviolet exposure, virtually the only way to kill the hardy viruses, the researchers say.

(Continue . . . )

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