Introduction Norovirus is a highly transmissible infection that causesa condition known as acute gastroenteritis which is defined as an inflammationof the intestinal lining which can result in multiple symptoms including;vomiting, diarrhea, and abdominal cramps, occasionally resulting in fever andmuscle aches as well. After contracting the virus, symptoms may take up to oneor two days to present themself and usually takes a healthy immune system abouttwo to three days to fight off. Those who are immunocompromised such as theelderly or children may have more difficulties overcoming the illness which cancause further complications if their symptoms persist. The infection can becontracted in one of three ways, the first of which is being in close contactwith another individual who was previously diagnosed with norovirus orexperiencing the symptoms mentioned above.
The second method is by touching acontaminated object or surface and then touching any open mucosal cavity of theface such as the eyes, nose, and/or mouth which would allow the virus to enterthe uninfected individuals’ system. The final method would be to consume foodor water that had been previously contaminated with the virus for variousreasons such as preparation of the food by an infected individual or drinkingwater that was unproperly filtered. There are no known treatments or anypreventative vaccinations available at this time and while some physicians mayprescribe antibiotics; they have been proven to be ineffective in the face ofviruses (“Norovirus infection,” 2017). Patients are simply advised to stay hydrated and allow the infection torun its course as the body’s immune system is capable of fighting it off giventime. Norovirushas an extreme global burden as it is known to be one of the most commoncausative agents of acute gastroenteritis in the U.S. and worldwide (“Norovirus,”2016). It has caused “200,000 deaths annually worldwide, with 70,000 or moreamong children in developing countries” (Lopman, 2015, p.
3). Within the UnitedStates, the CDC reports that it causes anywhere from 570 – 700 deaths per yearas seen in Figure 1. The virus has been able to make such a widespread impactbecause of its ability to live on surfaces and within the previously infectedindividuals’ feces and vomit for up to two weeks post recovery of theinfection; meaning that individuals who have already stopped experiencing thesymptoms can still pass the infection along to others. Another reason is thatunlike other viruses such as the common cold or flu; it is resistant to many ofthe disinfectants available for purchase on the market, so many individualsclean their homes believing the virus has been killed when it is still livingon multiple surfaces.
Figure 1Background Norovirus is prevalent in small enclosed areas housinglarge populations of individuals such as daycares, nursing homes, healthcarefacilities, and cruises. Of the facilities listed, cruise ships pose one of thehighest incidence rates of norovirus amongst the general population as it is avessel travelling by water between different geographic locations with thehighest traffic volume. All it takes is one infected individual experiencingany of the previously mentioned symptoms to board a cruise and they can quicklyspread the virus through touching common surfaces such as railings, doorknobs,and tabletops. By serving food to guests in an open style buffet, individualsbecome exposed to foods that have been tampered with by hundreds of others servingthemselves along with the added factor of the amount of time that the food isleft out which simply becomes a breeding ground for infectious agents in whichnorovirus is one of the many culprits in the contagion cocktail (Dell’Amore,2016). By focusing public health efforts including resources, interventions,and education for norovirus on the cruise ship industry, the frequency of casescan be lowered along with the potential risk of spreading the infectiontrans-globally.
Health Implications Norovirus is categorized in five separate groups labelledGI – GV which each further subdivide into more specific forms of the virus asdepicted in Figure 2. A new discovery, however, occurred in 2012; Sydney,Australia to be exact, and it was found to have been the most prominent strainof the virus not just in the U.S., but worldwide. This became known as theGII.4 Sydney strain as it belonged to the second group of norovirus taxonomyand then further classified under the fourth known genotype and named Sydneyfor its origin of discovery. This new strain of norovirus replaced thepreviously dominant strain, GII.
4 New Orleans which had emerged back in 2009.This GII.4 strain is said to evolve every few years which is why it createspeaks in the overall epidemiological transmission rate pattern which otherwisetends to stay high, yet steady (Prystajecky, 2013). Such can be observed in Figure3 with the number of norovirus outbreaks displayed along with the year andmonth during which it occurred along the y and x axis respectively and thevarious strains differentiated by color. Doing so allows for the obvioustransition between occurrence of GII.4 New Orleans outbreaks and GII.
4 Sydneyoutbreaks to be recognized. Figure 2 Figure 3Methodology To prevent and limit the number of norovirus outbreaksthat occur aboard cruise ships and similar marine vessels, the Centers forDisease Control and Prevention have taken the lead through an initiative knownas the Vessel Sanitation Program. The program, also referred to as the VSP,entails various preventative methods to limit the number of outbreaks thatoccur along with random inspections of the vessels to determine compliance withsanitation regulations.
Ships that fall within the jurisdiction of the VSPinclude ships that have any more than 15 individuals on board and docks at anyUS port meaning that international ships that do no dock at US ports are notincluded regardless of whether they carry American citizens or not. One of theunique, yet beneficial assets of the program in terms of research andprevention efforts is the Gastrointestinal Illness Surveillance system which iscomposed of set guidelines for reporting cases of acute gastroenteritis andnorovirus by staff members on the cruise ships throughout the duration of thetrip from the time the ship leaves port till the moment they dock at theirfinal destination. Medical staff on the cruise ship must record everyone whoexperiences any of the main symptoms of norovirus; diarrhea, vomiting, abdominalpain, fever, and/or muscle aches along with any individuals for whom they’vegiven an antidiarrheal medication. At specific intervals set by the program,cruise ships are to submit their findings, and this allows for two things.Firstly, the VSP can observe for new cases and determine when there are anyunusual increases that occur which would prompt an outbreak response whichentails another set of guidelines to be determined on a case by case basis bythe VSP. The other, is the overall research conducted with the epidemiologicaldata collected and the trends that can be detected over time which will furtheraid in prevention efforts in the long run (“Vessel Sanitation Program,” 2017). First Supporting Case An article posted in TheJournal of Infectious Diseases displays the effects of the newly emergedGII.4 – 2012 Sydney strain of Norovirus on the human body by determiningwhether it elicits the same immune response as that of previous strains ofnorovirus.
The study analyzed the new strain against GII. 4 – 2006 Minerva andGII.4 – 2009 New Orleans immune responses. By utilizing antibodies within thehuman immune system that had been previously mapped for binding to the virus inan area that would shut it down (blockade epitomes), researchers were able totest for a measurable response in both the previous norovirus strains alongwith the new one. They found that while the antibodies did bind and cause anactive immune response when introduced to the GII.4 – 2006 Minerva and GII.4 –2009 New Orleans, such was not the case for the GII.
4 – 2012 Sydney strain.There were two new epitomes, or spots of identifiable binding for the immunesystem on the virus, found on the GII.4 – 2012 Sydney strain that was notpreviously found on the older strains making it more difficult for the immunesystem to be able to detect and fight it off (Debbink, 2013, par. 1-7). From the results collected within the research article,one can estimate the effects which the newly emerged strain of norovirus, GII.
4Sydney can wreak amongst the general population. By highlighting the keydifference in structure between the old and new strains of norovirus, thearticle warns the reader that unlike the older strains which the body haslearned to put up a defense against, GII. 4 Sydney is a whole new monster thathas yet to meet its match. The previous strains have slowly decreased in incidenceover time, leading up to the evolution of the new strain due to individuals whobuilt up an immunity from previous exposures to the same strain along with anon-traditional herd immunity in which those who are armed to fight off theinfection from multiple exposures (as opposed to vaccination) are effectivelyprotecting those who have not previously been exposed, or in other wordssusceptible, to either the GII. 4 – 2006 Minerva and/or the GII.4 – 2009 NewOrleans strains.
Second Supporting Case In January of 2016, the Centers for Disease Control andPrevention published a Morbidity and Mortality Weekly Report highlighting thefindings collected from the Vessel Sanitation Program from the years of 2008 to2014. In the report, the incidence of those experiencing symptoms of acutegastroenteritis, the etiology (or the cause of said condition), and thecomparative analysis amongst varying etiologies throughout the duration of thesix years, were all mapped out and discussed. It was found that there was asudden spike in the number of cases of acute gastroenteritis in the year of2012 which coincides with the findings of previous literature on the outbreakof the GII. 4 Sydney strain of Norovirus and its mass effects on the cruiseship population as seen in Figures 4 and 5. The increase in incidence found onthe cruise ships also reflects that of findings on land which further drivesthe importance of the emergence of an evolutionized strain of the common virusthat most had already built a resistance to. Even those who had not yet alreadybuilt their own personal immune system response against the virus due to a lackof exposure were protected from it through a non-traditional herd immunity,however, this immunity falls ineffective in the face of the new strain whichcreates a new case for public health specialists to tackle to combat the suddenoutbreaks of a relatively common and previously steady virus (“Morbidity andMortality,” 2016).Figure 4 Figure 5 From this report, we can gather real time evidence of thevast increase in norovirus incidence rates that were previously predicted byresearch on the newly discovered strain of norovirus. It demonstrates thatwhile there were cases of acute gastroenteritis caused by norovirus circling inhigh numbers on cruise ships in previous years, the drastic incline in the yearof 2012 marks the GII.
4 Sydney strain as the most prevalent to date. While itmay be difficult to completely isolate the impact of each and every singlestrain of the virus and compare it to the impact caused by the GII. 4 Sydney,we can isolate the most prominent one, a title which was previously held by theGII. 4 New Orleans and report that the new strain has in fact superseded itspredecessor. Analysis While the first supporting case was an experimental innature, it relays key information regarding the structure of the virus whichallows researchers to analyze the effects which the virus may pose amongst thehuman population.
This also allows for other trained experts in the field, suchas epidemiologists or public health interventionists, to project the amount ofprevention efforts that will need to be made in order to combat potentialoutbreaks. This then sets the stage for the second supporting case to trulydemonstrate the importance of such a spike in cases of the norovirus infection.Experts utilize such information collaboratively to understand what causesthese outbreaks and ways in which we may not only combat the current issue athand, but also create new preventative protocols and regulations in place toensure it does not occur again and that if it does then it does so with minimalamounts of damage and harm done.
Solutions As mentioned earlier,there are no true methods of treatment known for norovirus as of yet, nor arethere any vaccinations available to protect against it as one would receive fora virus such as the flu. This does not mean, however, that one must assume fullsusceptibility to the infection and completely give up in all other preventionmethods. One can easily take certain precautions to increase their odds againstcontracting the virus as listed in the handout created by the Centers forDisease Control (“Norovirus Illness,” 2015). It lists out five main measures tobe taken in order for one to protect themselves and those around them fromnorovirus. The first is the golden rule of all public health prevention methodsand that is washing our hands.
Regardless of how evolved a virus strain may beagainst our body’s immune system, it will still be removed from the surface ofour hands with the use of antibacterial soap and the mechanical movement ofhandwashing. This not only prevents it from being introduced into one’s ownsystem, but also prevents the spread of it as well. Doing things such ascarefully washing fruits and vegetables for meal preparation and vigorouslywashing infected clothing are also ways to prevent the spread of norovirus. Conclusion While norovirus is a prominent infectious diseasepredominantly affecting the cruise ship population for many years, there arenew findings that may better our understanding of the infection and our effortsto stop it. The recent discovery of the new GII. 4 Sydney strain demonstratedthe importance of preparation in the case of the virus evolving and causingsudden outbreaks which could cause a worldwide pandemic as it did in 2012 whenthe strain first emerged. It may seem as though the new strain has increasedresistance against the human immune system along with its ability to liveindependently for long periods of time, organizations such as the Centers forDisease Control have created guidelines for individuals to follow to preventbecoming infected.
They have also created the Vessel Sanitation Program toprotect the vulnerable population of cruise ship travelers from norovirus asthey are not only the most at risk, but they are not also unable toindependently practice many of the preventative methods besides hand washingdue to their lack of control over food preparation, water treatment, andoverall sanitation of the ship. By combining these public health efforts, weare able to slowly decrease the impact of norovirus, despite the emergence ofnew strains, and improve the overall health of individuals within thepopulations that are most affected by the issue.
