By: Heather Williams

Norovirus.  That’s something you get on cruise ships, right?  Well, yes and no.  The associating with cruises ships is a bit of misnomer, but close proximity such as that you would get in the closed environment of a cruise ship is a fast way to spread the illness.  Norovirus is a very common virus that does not care about time of year, age, or health.  Though being a healthy adult can make it easier on you.  It is highly contagious and unlike some viruses, having been exposed does not offer any immunity for future exposure.  This is because there are so many versions of the virus and so many mutations you are likely to be exposed to a different on each time.

What are Some Statistics?

Each year Norovirus accounts for somewhere between 19 to 21 million cases of acute gastroenteritis.  Gastroenteritis is described as inflammation of the stomach and/or intestines.  That’s a lot of tummy aches.  More seriously, norovirus is responsible for somewhere between 56,000 to 71,000 hospitalizations and between 570-800 deaths each year, with deaths generally affecting the very young and the very old.  Of all the types of gastroenteritis, 16% can be linked back to Norovirus and 12% of acute gastroenteritis cases requiring outpatient care can be linked back to Norovirus.

When looking at pediatric cases, Norovirus is the leading cause of severe acute gastroenteritis among American children under the age of 5 years old.  This corresponds to 1 million pediatric medical visits each year.  1 in 278 children are hospitalized for Norovirus before they reach 5 years old.  1 in 14 children will visit an emergency room due to Norovirus before they reach 5 years old.  Another 1 in 6 will need outpatient medical care for Norovirus before they reach 5 years old.  That’s a lot for little tummies to deal with!

Norovirus is known to be the leading cause of foodborne illness in the United States, accounting for 58% of domestically-acquired foodborne illness.  This racks up quite a bill, costing about $2 billion for healthcare and loss of productivity in the United States.

How Do I Know I Have Norovirus?

Common symptoms of Norovirus include diarrhea, vomiting, nausea, stomach pain.  Others may experience headache, fever, and body aches.  These symptoms often start between 12 to 48 hours after exposure.  Most people experience symptoms resolving within 1 to 3 days from onset.  In the mean-time you will feel very sick.

It’s no surprise hat symptoms such as vomiting and diarrhea can lead to dehydration.  That can be very serious in the very young, the very old, and those with other illnesses.  Symptoms of dehydration to look out for include dry mouth and throat, decrease in urination, and feeling dizzy when standing up.  Children don’t really have a way to communicate how they are feeling.  To identify dehydration in children, you may have to pay attention to a few behaviors, such as crying without tears or only a few tears, unusual sleepiness or fussiness.

How Would I Get Norovirus?

Norovirus is transmitted in a way people don’t like to think about, considering most transmission of Norovirus is foodborne.  Norovirus is transmitted fecal-oral.  What that means, is that the virus is shed through the feces of an infected person and transmitted to another person when they inadvertently consume it. Now, I would imagine that no one is going around eating, well.  You know…  But you would be surprised at how much feces is actually floating around in our environment.  You don’t have to see it to be infected by it. In fact, even microscopic amounts – smaller than your eye can see – can infect you and make you sick.

This can easily be transferred if someone who is infected does not properly wash their hands after using the restroom, or someone who is caring for someone who is sick does not wash their hands after changing a diaper or taking care of that person.  Unfortunately, Norovirus can be present and shed in stool even before the patient starts feeling sick and can persist for two weeks or more after the patients’ symptoms resolve.  Though the most contagious periods are when the patient is very sick and during te first few days of recovery.

While some transmissions occur in the household, most large outbreaks happen in restaurants and other food service settings.  This is because someone who is infected may handle the food of many people in one day.  If someone who is sick with Norovirus does not properly wash their hands and touches ready-to-eat foods or foods that have already been cooked with bare hands, the food may become contaminated and infection is passed onto the unknowing recipient of the dish.

Other sources include foods such as fruits, vegetables, oysters, and other foods intended to eat raw that have been contaminated at the source, such as a contaminated water supply or sick farm worker.  Norovirus can also be spread through community water systems and often occurs when sewage contaminates wells and in untreated recreational water such as a pool or splash pad.

Areas in which people are in close quarters, especially involving food, allow Norovirus to spread rapidly.  Close quarters places include nursing homes, schools, daycares, and you guessed it – cruise ships.  This is why cruise ships get a bad reputation.  Though according to the Vessel Sanitation Program, 74 million passengers sailed on cruise ships between the years 2008 and 2014.  Only 129,678 passengers were reported to have acute gastrointestinal illness.  Only 1 in 10 of those cases were associated with a Norovirus outbreak.

How is Norovirus Diagnosed?

There are a couple different ways that clinical and public health laboratories can perform diagnostic tests for Norovirus.  The most widely used method is Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR).  Another method includes enzyme immunoassays (EIAs).

Genetic analysis using RT-qPCR detects the genetic material (RNA) of the virus.  A variety of samples can be used to test for Norovirus, including: environmental specimens and human specimens – stool and vomitus.  Stool specimens are the best sample type for RT-qPCR.  Samples are best when obtained within 48 to 72 hours of onset of symptoms.  Sometimes Norovirus can be found in stool samples taken up to 2 weeks after a person recovers.  For diagnostic purposes, the earlier the sample is taken the better.

EIAs are not very sensitive tests, so the US Food and Drug Administration (FDA) only recommends use of this type of diagnostic test for outbreaks and not for diagnosing individual cases.  The EIA would be used on sets of samples were Norovirus is likely to present instead of samples were health care providers are trying to rule out various causes of illness.  EIAs are helpful in characterizing Norovirus strains, which allows cases to linked together if the same strain is present, and allows more information to be analyzed to detect a common source of an outbreak.

How is Norovirus Treated?

Unfortunately, there is no specific treatment for Norovirus.  Since it is a virus and not a bacterium, antibiotics do nothing to treat the illness.  The best way to handle Norovirus illness is to treat the symptoms and replace lost fluid with plenty of liquids.  Sports drinks and oral rehydration fluids are helpful to battle mild dehydration.  If severe dehydration occurs, hospitalization may be needed and intravenous, or IV fluids may be administered.  Dehydration should be taken seriously, as this could lead to other organ and system failures.

How is Norovirus Prevented?

WASH YOUR HANDS!  Very simply, washing your hands before you eat or prepare foods is key in reducing foodborne Norovirus illness.  Eating food that was prepared by someone who has washed their hands helps reduce spread of Norovirus.  Avoid putting you hands in your mouth or touching food if you have not washed your hands.  Certainly and most importantly, everyone following proper handwashing procedures after using the bathroom, changing diapers, or cleaning up after someone who is sick can prevent the spread of Norovirus illness.