Hand sanitizer doesn’t work well on this nasty bug. So how to dodge norovirus symptoms this season?
UC Davis Health
Recently the California Department of Public Health (CDPH)
warned that norovirus — commonly known as the stomach flu — is “on the rise.”
As of Dec. 12, norovirus levels in wastewater in
the U.S. West and South were labeled “medium” according to data linked on the
department’s website, but were “high” in the U.S. Midwest and Northeast. As of
Dec. 20, levels were high at the Sacramento Regional Wastewater Treatment
Plant, as well as in San Francisco.
Norovirus is highly contagious, and it travels from person
to person a bit differently than the respiratory viruses that cause flu, COVID
and common colds. That can be both good and bad news.
Read on to arm yourself with more understanding
about norovirus symptoms and behavior — and how you can increase your chances
of avoiding this bug.
What is norovirus?
Norovirus is
one of several intestinal viruses that cause diarrhea, vomiting and gut cramps
that can last for multiple days. Sometimes, this can lead to dangerous levels
of dehydration.
When you hear about nasty outbreaks of stomach illness in
places like cruise ships, day cares and senior facilities, it’s highly likely
you’re hearing about norovirus. It’s sometimes even called “the cruise ship
virus.” These are all places where people spend time close to each other, and
where they usually eat and drink together from the same food source.
For many people, those conditions also happen during holiday
gatherings.
How long do norovirus symptoms last?
Symptoms usually start 12 to 48 hours after contact with the
virus, according to CDPH. A person may vomit and/or have diarrhea many times a
day, with symptoms usually lasting 1 to 3 days.
How is norovirus treated?
There’s no specific treatment for norovirus, and it usually
gets better on its own. There
are things you can do to ease symptoms, such as resting and drinking
extra liquids to help restore the fluids that you lose quickly during diarrhea
and vomiting.
When
symptoms are severe, health care providers may give intravenous
(IV) fluids to treat severe dehydration.
No licensed antiviral therapy (such as Tamiflu) is currently
available for norovirus. Some off-label agents are sometimes used for
immunocompromised patients with weakened immune systems.
How does norovirus spread?
It sounds gross, but norovirus mainly spreads when vomit or
particles of feces from an infected person get swallowed by an uninfected
person. This can happen in several ways.
- Foods
and drinks: When people don’t wash their hands when
making food, they are more likely to contaminate it.
- Surfaces
and objects: If your fingers then go into your mouth — or onto
objects like a chewed pen — norovirus can go
with them.
- Physical
contact: Shaking hands or caring for a member of your household
who is sick can also spread the virus.
According
to CDPH, a person is most contagious as soon as they start feeling
sick until a few days after symptoms stop. However, they may still be
contagious for two weeks or longer after feeling better.
Can you get norovirus by breathing it in?
Breathing in virus particles is not thought to be the
primary way that norovirus spreads. It doesn’t invade your body by infecting
cells inside your nose, mouth or airway like respiratory viruses. Instead, it
infects your gut after reaching it with food or saliva.
Generally, it isn’t recommended to wear a mask in a crowded
indoor place to avoid norovirus. However, it is possible that being near an
infected person while they’re sick, or while cleaning up after them, could
expose you to tiny droplets of vomit or feces that contain the virus.
Theoretically, these can enter your mouth, so wearing
a mask during clean-up can still be a good idea.
How contagious or spreadable is norovirus?
Norovirus is extremely contagious, with transmission
characteristics that are above flu and COVID but less than measles.
Why is norovirus so contagious?
Armor, for one. Norovirus has an outer shell of protein
that’s much tougher than the soft envelope of fat around viruses like the flu
or the novel coronavirus (COVID).
This protects the norovirus from many things that could kill
a lesser virus, such as:
- Temperature
swings: Noroviruses can live through temps as high as 145°F and
as low as freezing, helping it survive food storage and prep.
- Acidic
conditions: Norovirus can survive exposure to stomach acid.
- Cleaning
products: Hand
sanitizer doesn’t work well on norovirus. Neither do many
common cleaning wipes or products, unless registered
for killing norovirus.
- Weather
and physical contact: It can survive
for days or weeks on doorknobs, countertops, phones and hard
surfaces.
The amount of norovirus that it takes to cause illness is
also remarkably low – as
few as 18 to 1,000 viral particles. A single episode of vomiting
contains enough virus to infect 150,000 people.
How can I protect myself from norovirus?
For one, don’t eat food prepared by people who are sick or
were sick recently. But that can be hard to control. So, you can also make sure
that you clean your hands at key times, by washing them with soap and water for
at least 20 seconds.
A simple rule could be: “Before putting something in my
mouth, I make sure I’ve washed my hands first — especially in a group setting
or around someone who’s sick.”
If you’re really concerned about norovirus, here are some
examples of times you might want to be sure you wash your hands before eating:
- At
a shared meal, after serving dishes have made the rounds and
you’ve loaded your plate.
- While
snacking, if using shared serving utensils at the appetizer
table, or pouring drinks from a shared bottle.
- After
shaking hands when greeting someone at a gathering with food and
drink.
- At
a restaurant, after touching shared items like a menu, or the
serving utensils in a salad bar or buffet.
- At
the workplace, if you’re snacking while using a computer or other
equipment.
If you can’t wash your hands before touching food and you’re
very concerned about norovirus, you could also stick to eating with utensils
only.
How best to kill norovirus when doing dishes?
Cleaning dishes and utensils in a dishwasher is the most
reliable method to prevent norovirus spread. That is because the water
typically reaches 140-160°F in the sanitizing cycle.
The blend of hot water and detergents used in dishwashers is
sufficient to decontaminate dishware and eating utensils exposed to norovirus.
No special precautions are needed beyond standard dishwashing practices.
Can I track norovirus levels?
Public health officials can look for trends and spikes by
watching how much virus shows up at wastewater treatment plants in different
communities, using tools such as the WastewaterSCAN program.
State and local health officials also track outbreaks of norovirus, which is when two or more people get sick from a common source. They may issue alerts through the news media and social media.
