Amidst the ongoing battle against the flu, Americans now have a new virus with which to contend– one that is more infectious and more persistent than its partner in crime. A novel norovirus strain, GII.4 Sydney, is rapidly leaving a sickly trail of misfortunate patients in its wake. Australia, Japan, the United Kingdom and now the United States are only a few of the countries hit by the Sydney strain, and their citizens are not happy.
GII.4 Sydney strain
Norovirus Sydney seems to be a particularly infectious version of the virus, but the symptoms remain the same for all norovirus strains. Patients usually suffer from cramping, diarrhea, vomiting, and general misery until the illness subsides, usually after a couple of days. No treatment exists, however the CDC highlights the importance of drinking plenty of fluids as dehydration is one of the leading causes of death associated with norovirus infection. The United States sees about 21 million cases and 800 deaths from norovirus every year, making it the leading cause of gastroenteritis in the country.
It is not uncommon to see a marked increase in norovirus cases during the winter season, yet ‘Sydney 2012’ is wreaking special havoc across the globe. The strain was first identified in Australia in March 2012 and has since caused multiple large-scale outbreaks across different continents. Between September and December 2012, 53 percent of norovirus outbreaks in the United States were caused by Sydney, according to the CDC. Fifty-one percent of these resulted from direct person-to-person contact, followed by foodborne outbreaks (20 percent).
‘Cruise Ship Disease’
Given its impressive tenacity, it is almost impossible to get rid of norovirus with the usual arsenal of cleaning products. The CDC recommends using harsher chemicals, such as bleach and hydrogen peroxide, to clean kitchen countertops and other surfaces where norovirus tends to linger. And forget about Purell. Our hands, known cesspools of germs and bugs, require forceful scrubbing with hot water and soap for at least thirty seconds. In fact, norovirus outbreaks are six times more likely to occur in health facilities that use hand sanitizers in place of hand washing.
It is not surprising then that norovirus tends to spread fiercely and most effectively in enclosed, crowded spaces, like cruise ships for example. In the last two months alone, hundreds of passengers and crewmembers were forced below deck, violently ill. Ironically, seasickness had nothing to do with it. The microbial culprit, norovirus Sydney, infected travelers due to contaminated food and water.
The Emerald Princess, which docked in Ft. Lauderdale in late December, carried 196 norovirus-infected passengers and crew, who were asked to isolate themselves until deemed no long contagious. Similarly, the Crown Princess, which departed from Texas for Italy, reported over 100 norovirus cases during the 20-day journey. Brooklyn’s Queen Mary 2 was forced to dock in St. Maarten due to more than 200 sick passengers.
Follow the data
Despite the noteworthy number of reported cases, norovirus activity usually peaks in January. The CDC is awaiting last month’s data before confirming Sydney’s impressive virulence.
We, at The Disease Daily, decided to do a bit of data cranking of our own, using HealthMap alerts. The results were interesting but not altogether surprising! In 2010 and 2011, HealthMap aggregated 464 and 331 breaking norovirus alerts, respectively. This figure skyrocketed to 1,139 alerts in 2012. Similarly, January 2013 alone boasts 251 norovirus alerts. This is already significantly more than half of the alerts seen in all of 2011. Time will tell whether the CDC agrees with these figures or whether other factors, such as improvements in the HealthMap alert system are at work.
Noroviruses are classified into five genogroups, which are then further divided into at least 34 genotypes. Of these, noroviruses GI and GII cause illness in humans and most outbreaks are due to GII.4 strains. Every two to three years, noroviruses mutate and new strains develop. This development is often followed by an increase in outbreak activity, as is likely with the GII.4 Sydney strain.
Given the mutable nature of noroviruses, it has been exceedingly difficult to develop an effective vaccine. Recently, Montana’s Ligocyte Pharmaceuticals developed a norovirus vaccine that may give overworked health professionals a break.
This new vaccine candidate is injectable and thus more immunogenic, or able to trigger an immune response in the body. The University of Rochester Medical Center in New York is one of five groups testing the vaccines effectiveness. Outcomes of the trials will determine whether this new vaccine will prove more successful than previous attempts, which came in the form of nasal sprays. In the mean time, remember to wash your hands.