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.
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:
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.
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