Norovirus (Norwalk Virus) | Transmission, Pathogenesis, Symptoms, Prevention

Summary

The video script discusses norovirus, a highly contagious virus causing acute gastroenteritis. Originating from Norwalk, Ohio in 1968, it's prevalent in winter and spreads via the fecal-oral route. Symptoms include abdominal pain, nausea, vomiting, and diarrhea, lasting 48-72 hours. Diagnosed clinically, treatment is supportive focusing on hydration. Prevention involves thorough hand-washing with soap and water and sanitizing with bleach, as norovirus is resistant to alcohol sanitizers.

Takeaways

• 🦠 Norovirus is a highly contagious virus that causes acute viral gastroenteritis and is the most common cause worldwide.
• ❄️ It is more prevalent in winter months, hence the nickname 'winter vomiting disease'.
• 🤒 Transmission occurs mainly through the fecal-oral route, often via contaminated water or food, particularly leafy greens.
• 👐 The virus can be shed in an infected person's stool for up to several weeks, even after symptoms have resolved.
• 🔬 Norovirus is resistant to alcohol sanitizers, requiring bleach for effective environmental decontamination.
• 🤮 Symptoms include sudden onset of abdominal pain, non-bloody vomiting, and non-bloody diarrhea, with vomiting being more common than diarrhea.
• 🏥 Diagnosis is primarily clinical, based on symptoms, though real-time qPCR can be used to confirm in outbreak situations.
• 💊 Treatment is supportive, focusing on hydration and symptom management, as it is a self-limiting infection.
• 🚫 There is no specific diet proven to reduce symptoms or duration, and the BRAT diet is not supported by evidence.
• 🧼 Prevention is key, emphasizing handwashing with soap and water and avoiding alcohol-based sanitizers.
• 🏃‍♂️ Asymptomatic individuals can still shed the virus, highlighting the importance of hygiene even when feeling well.

Q & A

What is norovirus?

Norovirus is a highly contagious virus belonging to the Caliciviridae family. It causes acute viral gastroenteritis, which is inflammation of the gastrointestinal system.

How is norovirus transmitted?

Norovirus is transmitted through the fecal-oral route, which can occur through contaminated hands, objects, water sources, and food supplies, particularly leafy greens.

Why is norovirus more common in winter?

Norovirus is more likely to occur in winter months due to people being indoors more often, leading to closer contact and easier spread of the virus.

What are the symptoms of norovirus?

Common symptoms include abdominal pain, nausea, vomiting (which is the most common symptom), watery diarrhea, myalgias, headaches, and fatigue. Fever occurs in approximately 50% of cases.

How long does the norovirus incubation period last?

The incubation period for norovirus is roughly 24 to 48 hours, after which symptoms begin to appear.

How long do norovirus symptoms typically last?

Symptoms of norovirus usually last for about 48 to 72 hours, but can last longer in immunocompromised individuals.

Can norovirus be diagnosed using a specific test?

Diagnosis is primarily clinical, based on symptoms. However, real-time qPCR can be used to detect the virus's genetic material, especially in cases of epidemics.

What is the treatment for norovirus?

Treatment is supportive, focusing on keeping the patient hydrated. There is no specific cure for norovirus as it is a self-limited infection.

Is there a vaccine for norovirus?

There is currently no vaccine available for norovirus, although research is ongoing.

How can norovirus be prevented?

Prevention involves hand washing with soap and water, as norovirus is resistant to alcohol sanitizers. Bleach is required to sanitize contaminated environments.

What is the significance of the term 'BRAT diet' in relation to norovirus?

The BRAT diet (bananas, rice, applesauce, and toast) is sometimes suggested for patients with norovirus, but there is no strong evidence to support its use in reducing symptoms or the length of infection.

Outlines

00:00

🦠 Understanding Norovirus

The first paragraph discusses the norovirus, a common cause of gastrointestinal upset and its high infectiousness. It explains the virus's classification as part of the Caliciviridae family, its seven genogroups, and identical symptoms across them. The paragraph also covers the virus's prevalence, its peak occurrence in winter months, and its transmission through the fecal-oral route. It details how the virus spreads via contaminated hands, objects, water, and food, particularly leafy greens. The norovirus's stability in the environment and its ability to be shed in stool for weeks post-infection are highlighted, emphasizing the risk of prolonged transmission. The paragraph also describes the incubation period and how the virus affects the gastrointestinal system, leading to symptoms like decreased gastric emptying, jejunal lesions, and malabsorption of fats, which result in diarrhea.

05:01

🤢 Symptoms and Management of Norovirus

The second paragraph delves into the symptoms of norovirus, which include abdominal pain, nausea, vomiting, and watery diarrhea. It notes that vomiting is more common than diarrhea and that fever occurs in about half of the cases. Other symptoms like muscle aches, headaches, and fatigue are also mentioned. The paragraph addresses the duration of symptoms, typically 48 to 72 hours, with a longer duration in immunocompromised individuals. It also touches on asymptomatic carriers who can still spread the virus. The diagnostic process is briefly mentioned, with a focus on clinical diagnosis and the use of real-time qPCR in epidemic situations. The treatment is supportive, emphasizing hydration and symptom management. The paragraph concludes with prevention strategies, including hand-washing with soap and water, the ineffectiveness of alcohol sanitizers, and the necessity of using bleach to sanitize contaminated environments. It also mentions the absence of a norovirus vaccine and encourages viewers to seek more information on infectious diseases.

Keywords

💡Norovirus

Norovirus is a highly contagious virus that causes acute gastroenteritis, which is an inflammation of the gastrointestinal tract. It is the most common cause of gastroenteritis worldwide. In the script, norovirus is described as a viral agent that can lead to symptoms like vomiting, diarrhea, and stomach cramps. It is often referred to as the 'winter vomiting disease' due to its prevalence during colder months when people are in close proximity.

💡Gastroenteritis

Gastroenteritis is an inflammation of the gastrointestinal tract, often resulting in symptoms such as diarrhea, vomiting, and abdominal pain. The script explains that norovirus causes acute viral gastroenteritis, highlighting that it is both sudden and caused by a virus, affecting the stomach and intestines.

💡Fecal-oral route

The fecal-oral route is a primary mode of transmission for many diseases, including norovirus, where the virus is spread through the ingestion of fecal matter, often via contaminated food, water, or surfaces. The script mentions that norovirus is transmitted through this route, emphasizing the importance of hand hygiene in preventing infection.

💡Viral shedding

Viral shedding refers to the process by which a virus is expelled from an infected individual, often in bodily fluids such as saliva, respiratory droplets, or feces. The script explains that norovirus is shed in the stool of infected individuals, which is a key factor in its transmission.

💡Incubation period

The incubation period is the time between exposure to a pathogen and the appearance of the first symptoms of the disease. For norovirus, the script states that the incubation period is roughly 24 to 48 hours, after which an infected individual begins to show symptoms.

💡Gastric emptying

Gastric emptying is the process by which the stomach releases its contents into the small intestine. The script suggests that norovirus decreases gastric emptying, which may be a reason for the nausea and vomiting associated with the infection.

💡Jejunum

The jejunum is the middle section of the small intestine, which plays a crucial role in nutrient absorption. The script mentions that norovirus can cause lesions in the jejunum, contributing to malabsorption and diarrhea.

💡BRAT diet

The BRAT diet, which stands for bananas, rice, applesauce, and toast, is a bland diet sometimes recommended for individuals with gastrointestinal issues. The script questions the effectiveness of the BRAT diet in treating norovirus, suggesting that there is no strong evidence to support its use.

💡Hydration

Hydration is the maintenance of adequate water levels in the body, which is crucial when dealing with conditions that cause vomiting and diarrhea, like norovirus. The script emphasizes the importance of staying hydrated as part of the supportive treatment for norovirus.

💡Hand-washing

Hand-washing is a fundamental hygiene practice for preventing the spread of infections. The script stresses that hand-washing with soap and water is essential in preventing norovirus because the virus is resistant to alcohol sanitizers.

💡Bleach

Bleach is a disinfectant used to clean and sanitize surfaces. The script specifies that bleach is necessary to sanitize environments contaminated with norovirus because the virus is very stable and resistant to other sanitizers.

Highlights

Norovirus is a common cause of gastrointestinal upset and is highly infectious.

Norovirus belongs to the family Caliciviridae and has seven genogroups.

The name 'norovirus' comes from the first outbreak in Norwalk, Ohio, in 1968.

Norovirus is the most common viral cause of gastroenteritis worldwide.

It is often called the 'winter vomiting disease' due to its prevalence in winter months.

Transmission occurs through the fecal-oral route, often via contaminated surfaces or food.

The virus can be shed in stool for up to four weeks, even after symptoms resolve.

Norovirus is very stable in the environment, requiring special disinfection methods.

Incubation period is typically 24 to 48 hours before symptoms appear.

Symptoms include abdominal pain, nausea, vomiting, and watery diarrhea.

Vomiting is the most common symptom of norovirus.

Symptoms usually last for 48 to 72 hours but can be longer in immunocompromised individuals.

Asymptomatic individuals can still shed the virus and spread infection.

Diagnosis is clinical, based on symptoms, and confirmed with real-time qPCR in some cases.

Treatment is supportive, focusing on hydration and symptom management.

The BRAT diet and probiotics have not been proven effective for norovirus treatment.

Prevention involves handwashing with soap and water, and sanitizing with bleach.

There is no vaccine currently available for norovirus.

Transcripts

norovirus like the neuro fires are very

common causes of gastrointestinal upset

and are very infectious in the system we

talk about how we become infected with

these viruses we're also in chocolate

signs and symptoms how we can diagnose

and how we can treat it and most

importantly proper methods to prevent or

reduce the risk of becoming infected

with this virus in the first place so

the norovirus is a virus in the viral

family khaleesi viridi these are small

non envelope RNA viruses and there are

actually seven Geno groups of the

norovirus but all of them have the same

symptoms

so the norovirus causes an acute viral

gastroenteritis so important is it's

acute it's viral and it's a

gastroenteritis so itís meaning

inflammation so information of the

gastrointestinal system and in fact the

norovirus is so common that it's

actually the most common viral cause of

gastroenteritis worldwide in the name

norovirus actually is derived from the

place of its first outbreak in that

place was actually Norwalk Ohio United

States in the year 1968

so the norovirus is often called the

Norwalk virus because of this reason and

the norovirus is more likely to occur in

the winter months most likely due to

individuals being inside more often in

close contact the virus can spread more

easily so it's also known as the winter

vomiting disease so how is the norovirus

transmitted it's transmitted through the

fecal-oral route so if we see an

individual who has the norovirus you

want to look at their family members you

want to look at family members with

similar illnesses because those same

members can easily pass it along to

others through the fecal-oral route so

how does this happen so what happens is

an infected individual can essentially

become contaminated on their hands that

can touch different objects like full

mites which are objects like furniture

can come from contaminated water sources

so if feces from an infected individual

it's in two water supply it can lead to

contaminated water individuals drinking

that water can become infected and

related to this is also contaminated

food supplies so specifically the leafy

greens so contaminated water is getting

onto leafy greens if those greens aren't

washed properly we can get the virus on

those foods and it's very virulent it

only requires very small amounts of

virus to cause an infection usually less

than 100 viral particles so even a small

amount of virus can lead to an infection

in I alluded to this before but the

norovirus is shed in the stool from

infected individuals that is how it is

transmitted so again it's shed in the

stool and it's picked up in other places

an individual who's perhaps hasn't

washed their hands properly you can

touch objects and contaminate those

objects or can get into water or food

and what's really challenging about the

norovirus is that it can be shed in the

stool of an individual for approximately

four weeks and even months in some

patients especially patients with immuno

compromised so even after individuals

have gotten better they've resolved the

infection they can still be shedding the

virus for weeks but the good news is

that transmission of the norovirus is

more likely to happen if a patient is

symptomatic compared to if they're

asymptomatic but it can still happen if

they're asymptomatic and what's really

challenging about the norovirus is that

it is very very stable in the

environment so because of this we have

special ways to deal with this fires and

we're going to talk about that in a

later slides so once an individual does

become infected the incubation period is

roughly 24 to 48 hours so it takes about

24 to 48 hours after becoming infected

with the norovirus to actually start

showing symptoms so how does the

norovirus actually infect and cause

illness so what the norovirus does is it

affects the gastrointestinal system so

the stomach and intestines so what it

does to the stomach is that it decreases

gastric emptying and it's hypothesized

that this is actually the reason why

norovirus causes nausea and vomiting the

norovirus has also been shown to cause

lesions in the jejunum which is a part

of the small intestine in the norovirus

has also been shown to cause

malabsorption by affecting the intestine

mucosa and what it does is it reduces

the activity of enzymes like trelles and

alkaline phosphatase and it also

inhibits the absorption of fats so this

is how the norovirus is likely causing

diarrhea so again the norovirus is

leading to decreased gastric emptying

jejunal lesions and the

priest enzyme activity of trolleys and

alkaline phosphatase as well as

decreased absorption of fats leading to

diarrhea so after the incubation period

signs and symptoms of the norovirus

occur suddenly there's an abrupt onset

of symptoms and some of those common

symptoms of norovirus include abdominal

pain which is described as cramping in

nature and nausea and vomiting like we

mentioned previously and the National

vomiting is actually the most common

symptom of the norovirus but what we do

see is that the vomiting is non bloody

and non bilious we can also see watery

diarrhea again the diarrhea is non

bloody as well and it's described as

moderate diarrhea it's not excessive

like some other gastrointestinal

conditions but you do see four-day bowel

movements per day but what we do see

with the norovirus and what is key to

the norovirus is that nausea and

vomiting occur more often than diarrhea

so there are other viruses that cause an

acute viral gastroenteritis but if you

see an individual with more vomiting

than they are having diarrhea it's more

likely a norovirus

causing the infection and fever doesn't

always happen it's estimated that it

occurs in approximately 50% of cases

some of the other symptoms of the

norovirus include myalgias so achy

muscles headaches and fatigue so very

tired and what we do see is that

symptoms of the norovirus lasts for

about 48 to 72 hours but what's

important to recognize is that it may

last longer in some individuals

particularly in individuals with immuno

compromised and those individuals have

longer presentations and more severe

presentation so more severe symptoms but

we do also see some patients that become

infected with the norovirus and are

asymptomatic and this seems to occur in

approximately 1 in 10 patients even

though they're a somatic they can still

shed the virus in stool which means that

they can still spread the infection and

even after a patient has resolved the

infection so what we do find is that the

resolution of symptoms comes on very

quickly as well but even after they have

recovered from the infection they can

still have symptoms after the infection

and some of these include Harper and

constipation so some residual issues

with the gastrointestinal system so how

do we diagnose and how do we treat the

norovirus so when we're diagnosing this

infection when we're looking at

laboratory investigations we often see a

normal leukocyte count but in some cases

it can be mildly elevated and this

diagnosis is a clinical one so we see a

patient they're having those symptoms we

talked about before we see that they're

having more vomiting than diarrhea so

it's more likely to be norovirus causing

the gastroenteritis and the symptoms

resolved in 42 72 hours that's a

clinical diagnosis of norovirus in some

cases they may also do a real-time qPCR

specifically in cases where they're

looking for the source of an epidemic of

the norovirus so they want to make sure

that the cases are actually the

norovirus so they actually use the

real-time qpcr and detect the viral

genetics of the norovirus once we make

the diagnosis what is the treatment so

as I mentioned before the norovirus is a

self-limited infection the symptoms

resolve spontaneously so the treatment

is supportive so you want to make sure

that the patient stays hydrated and we

can also try to treat some of their

symptoms like the knowledge by using

anti nausea and there are some questions

as to should be use specific diet when

patients have the norovirus and there's

something called the BRAT diet which

stands for bananas rice applesauce and

toast and there was some question as to

should we use the BRAT diet to kind of

help their symptoms or to maybe reduce

the length of infection but there

doesn't seem to be any evidence to

support this and there's so some

question as to should we use probiotics

when they have this infection should we

use zinc again the evidence here is weak

as I mentioned before the norovirus is

extremely stable in the environment so

we have to use specific methods to

prevent it and those specific methods

are hand washing with soap and water we

have to use soap and water because it's

actually resistant to alcohol sanitizers

so even if we use an alcohol sanitizer

that's not going to cut it the norovirus

is actually resistant to alcohol

sanitizers and we have to use bleach to

sanitize a contaminated environment

other sanitizers don't work

the virus is too stable it's too

resistant so we actually have to use

bleach so again we need to use soap and

water for hand-washing we can't use

alcohol sanitizers with norovirus and we

have to use bleach to sanitize the

contaminated environment and there is no

vaccine currently available so there is

still some work ongoing as to the

development of a norovirus vaccine but

it is currently not available so again

it's a clinical diagnosis of norovirus

we use real-time qpcr in the event of

finding the source of the viral epidemic

treatment is supportive

it's a self-limited infection and

prevention requires hand-washing with

soap and water and no alcohol sanitizers

and we need to use bleach to sanitize a

contaminated environment so if you want

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