Introduction defined as an inflammation of the intestinal lining


            Norovirus is a highly transmissible infection that causes
a condition known as acute gastroenteritis which is defined as an inflammation
of the intestinal lining which can result in multiple symptoms including;
vomiting, diarrhea, and abdominal cramps, occasionally resulting in fever and
muscle aches as well. After contracting the virus, symptoms may take up to one
or two days to present themself and usually takes a healthy immune system about
two to three days to fight off. Those who are immunocompromised such as the
elderly or children may have more difficulties overcoming the illness which can
cause further complications if their symptoms persist. The infection can be
contracted in one of three ways, the first of which is being in close contact
with another individual who was previously diagnosed with norovirus or
experiencing the symptoms mentioned above. The second method is by touching a
contaminated object or surface and then touching any open mucosal cavity of the
face such as the eyes, nose, and/or mouth which would allow the virus to enter
the uninfected individuals’ system. The final method would be to consume food
or water that had been previously contaminated with the virus for various
reasons such as preparation of the food by an infected individual or drinking
water that was unproperly filtered. There are no known treatments or any
preventative vaccinations available at this time and while some physicians may
prescribe antibiotics; they have been proven to be ineffective in the face of
viruses (“Norovirus infection,” 2017). 
Patients are simply advised to stay hydrated and allow the infection to
run its course as the body’s immune system is capable of fighting it off given

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has an extreme global burden as it is known to be one of the most common
causative agents of acute gastroenteritis in the U.S. and worldwide (“Norovirus,”
2016). It has caused “200,000 deaths annually worldwide, with 70,000 or more
among children in developing countries” (Lopman, 2015, p. 3). Within the United
States, the CDC reports that it causes anywhere from 570 – 700 deaths per year
as seen in Figure 1. The virus has been able to make such a widespread impact
because of its ability to live on surfaces and within the previously infected
individuals’ feces and vomit for up to two weeks post recovery of the
infection; meaning that individuals who have already stopped experiencing the
symptoms can still pass the infection along to others. Another reason is that
unlike other viruses such as the common cold or flu; it is resistant to many of
the disinfectants available for purchase on the market, so many individuals
clean their homes believing the virus has been killed when it is still living
on multiple surfaces.


Figure 1


            Norovirus is prevalent in small enclosed areas housing
large populations of individuals such as daycares, nursing homes, healthcare
facilities, and cruises. Of the facilities listed, cruise ships pose one of the
highest incidence rates of norovirus amongst the general population as it is a
vessel travelling by water between different geographic locations with the
highest traffic volume. All it takes is one infected individual experiencing
any of the previously mentioned symptoms to board a cruise and they can quickly
spread the virus through touching common surfaces such as railings, doorknobs,
and tabletops. By serving food to guests in an open style buffet, individuals
become exposed to foods that have been tampered with by hundreds of others serving
themselves along with the added factor of the amount of time that the food is
left out which simply becomes a breeding ground for infectious agents in which
norovirus 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 cases
can be lowered along with the potential risk of spreading the infection

Health Implications

            Norovirus is categorized in five separate groups labelled
GI – GV which each further subdivide into more specific forms of the virus as
depicted 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 strain
of the virus not just in the U.S., but worldwide. This became known as the
GII.4 Sydney strain as it belonged to the second group of norovirus taxonomy
and then further classified under the fourth known genotype and named Sydney
for its origin of discovery. This new strain of norovirus replaced the
previously 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 creates
peaks in the overall epidemiological transmission rate pattern which otherwise
tends to stay high, yet steady (Prystajecky, 2013). Such can be observed in Figure
3 with the number of norovirus outbreaks displayed along with the year and
month during which it occurred along the y and x axis respectively and the
various strains differentiated by color. Doing so allows for the obvious
transition between occurrence of GII.4 New Orleans outbreaks and GII.4 Sydney
outbreaks to be recognized.

Figure 2  






Figure 3


            To prevent and limit the number of norovirus outbreaks
that occur aboard cruise ships and similar marine vessels, the Centers for
Disease Control and Prevention have taken the lead through an initiative known
as the Vessel Sanitation Program. The program, also referred to as the VSP,
entails various preventative methods to limit the number of outbreaks that
occur along with random inspections of the vessels to determine compliance with
sanitation regulations. Ships that fall within the jurisdiction of the VSP
include ships that have any more than 15 individuals on board and docks at any
US port meaning that international ships that do no dock at US ports are not
included regardless of whether they carry American citizens or not. One of the
unique, yet beneficial assets of the program in terms of research and
prevention efforts is the Gastrointestinal Illness Surveillance system which is
composed of set guidelines for reporting cases of acute gastroenteritis and
norovirus by staff members on the cruise ships throughout the duration of the
trip from the time the ship leaves port till the moment they dock at their
final destination. Medical staff on the cruise ship must record everyone who
experiences any of the main symptoms of norovirus; diarrhea, vomiting, abdominal
pain, fever, and/or muscle aches along with any individuals for whom they’ve
given 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 any
unusual increases that occur which would prompt an outbreak response which
entails another set of guidelines to be determined on a case by case basis by
the VSP. The other, is the overall research conducted with the epidemiological
data collected and the trends that can be detected over time which will further
aid in prevention efforts in the long run (“Vessel Sanitation Program,” 2017).

First Supporting Case

            An article posted in The
Journal of Infectious Diseases displays the effects of the newly emerged
GII.4 – 2012 Sydney strain of Norovirus on the human body by determining
whether it elicits the same immune response as that of previous strains of
norovirus. The study analyzed the new strain against GII. 4 – 2006 Minerva and
GII.4 – 2009 New Orleans immune responses. By utilizing antibodies within the
human immune system that had been previously mapped for binding to the virus in
an area that would shut it down (blockade epitomes), researchers were able to
test for a measurable response in both the previous norovirus strains along
with the new one. They found that while the antibodies did bind and cause an
active 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 immune
system on the virus, found on the GII.4 – 2012 Sydney strain that was not
previously found on the older strains making it more difficult for the immune
system 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.4
Sydney can wreak amongst the general population. By highlighting the key
difference in structure between the old and new strains of norovirus, the
article warns the reader that unlike the older strains which the body has
learned to put up a defense against, GII. 4 Sydney is a whole new monster that
has yet to meet its match. The previous strains have slowly decreased in incidence
over time, leading up to the evolution of the new strain due to individuals who
built up an immunity from previous exposures to the same strain along with a
non-traditional herd immunity in which those who are armed to fight off the
infection from multiple exposures (as opposed to vaccination) are effectively
protecting those who have not previously been exposed, or in other words
susceptible, to either the GII. 4 – 2006 Minerva and/or the GII.4 – 2009 New
Orleans strains.

Second Supporting Case

            In January of 2016, the Centers for Disease Control and
Prevention published a Morbidity and Mortality Weekly Report highlighting the
findings collected from the Vessel Sanitation Program from the years of 2008 to
2014. In the report, the incidence of those experiencing symptoms of acute
gastroenteritis, the etiology (or the cause of said condition), and the
comparative analysis amongst varying etiologies throughout the duration of the
six years, were all mapped out and discussed. It was found that there was a
sudden spike in the number of cases of acute gastroenteritis in the year of
2012 which coincides with the findings of previous literature on the outbreak
of the GII. 4 Sydney strain of Norovirus and its mass effects on the cruise
ship population as seen in Figures 4 and 5. The increase in incidence found on
the cruise ships also reflects that of findings on land which further drives
the importance of the emergence of an evolutionized strain of the common virus
that most had already built a resistance to. Even those who had not yet already
built their own personal immune system response against the virus due to a lack
of exposure were protected from it through a non-traditional herd immunity,
however, this immunity falls ineffective in the face of the new strain which
creates a new case for public health specialists to tackle to combat the sudden
outbreaks of a relatively common and previously steady virus (“Morbidity and
Mortality,” 2016).

Figure 4

Figure 5

            From this report, we can gather real time evidence of the
vast increase in norovirus incidence rates that were previously predicted by
research on the newly discovered strain of norovirus. It demonstrates that
while there were cases of acute gastroenteritis caused by norovirus circling in
high numbers on cruise ships in previous years, the drastic incline in the year
of 2012 marks the GII. 4 Sydney strain as the most prevalent to date. While it
may be difficult to completely isolate the impact of each and every single
strain 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 the
GII. 4 New Orleans and report that the new strain has in fact superseded its


            While the first supporting case was an experimental in
nature, it relays key information regarding the structure of the virus which
allows researchers to analyze the effects which the virus may pose amongst the
human population. This also allows for other trained experts in the field, such
as epidemiologists or public health interventionists, to project the amount of
prevention efforts that will need to be made in order to combat potential
outbreaks. This then sets the stage for the second supporting case to truly
demonstrate the importance of such a spike in cases of the norovirus infection.
Experts utilize such information collaboratively to understand what causes
these outbreaks and ways in which we may not only combat the current issue at
hand, but also create new preventative protocols and regulations in place to
ensure it does not occur again and that if it does then it does so with minimal
amounts of damage and harm done.


            As mentioned earlier,
there are no true methods of treatment known for norovirus as of yet, nor are
there any vaccinations available to protect against it as one would receive for
a virus such as the flu. This does not mean, however, that one must assume full
susceptibility to the infection and completely give up in all other prevention
methods. One can easily take certain precautions to increase their odds against
contracting the virus as listed in the handout created by the Centers for
Disease Control (“Norovirus Illness,” 2015). It lists out five main measures to
be taken in order for one to protect themselves and those around them from
norovirus. The first is the golden rule of all public health prevention methods
and that is washing our hands. Regardless of how evolved a virus strain may be
against our body’s immune system, it will still be removed from the surface of
our hands with the use of antibacterial soap and the mechanical movement of
handwashing. This not only prevents it from being introduced into one’s own
system, but also prevents the spread of it as well. Doing things such as
carefully washing fruits and vegetables for meal preparation and vigorously
washing infected clothing are also ways to prevent the spread of norovirus.



            While norovirus is a prominent infectious disease
predominantly affecting the cruise ship population for many years, there are
new findings that may better our understanding of the infection and our efforts
to stop it. The recent discovery of the new GII. 4 Sydney strain demonstrated
the importance of preparation in the case of the virus evolving and causing
sudden outbreaks which could cause a worldwide pandemic as it did in 2012 when
the strain first emerged. It may seem as though the new strain has increased
resistance against the human immune system along with its ability to live
independently for long periods of time, organizations such as the Centers for
Disease Control have created guidelines for individuals to follow to prevent
becoming infected. They have also created the Vessel Sanitation Program to
protect the vulnerable population of cruise ship travelers from norovirus as
they are not only the most at risk, but they are not also unable to
independently practice many of the preventative methods besides hand washing
due to their lack of control over food preparation, water treatment, and
overall sanitation of the ship. By combining these public health efforts, we
are able to slowly decrease the impact of norovirus, despite the emergence of
new strains, and improve the overall health of individuals within the
populations that are most affected by the issue.