Terrible Stomach Flu Still Going Around: GII.4 Norovirus Update


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It only takes 18 particles to make someone sick. Image by the CDC.

It only takes 18 particles of the norovirus to make someone sick. Image by the CDC.

Stomach cramps, vomiting, diarrhea, and body aches are all signs that you might have the norovirus, or commonly known as the ‘stomach bug’ or ‘cruise ship bug’ – even though it’s caused by restaurant workers more often than cruise ship conditions.

The norovirus is highly contagious and can make you miserable for days. While there is no specific cure for the norovirus, you’ll generally recover within a few days without the need for medical treatment.

However, some people, especially the elderly, young children, and those with compromised immune systems may have a more severe case due to weakened immune systems.

The current strain circulating, GII.4, is pretty vicious.

Many of our readers have made comments and asked questions regarding the severity and longevity of this virus, so we contacted the Centers for Disease Control and Prevention (CDC) and Dr. Peter White, Professor of Microbiology and Molecular Biology at The University of New South Wales in Australia, lead researcher on the team that isolated the GII.4 Sydney strain, to get you answers.

Unfortunately, the CDC doesn’t track cases of the norovirus, and, according to the information they provided us, aren’t aware of a difference in the severity between the GII.4 strain and earlier strains that only last 1-3 days.

Stomach Flu Going Around: Your Questions Answered

In addition to concerns about the length and severity of this strain of stomach flu, one reader commented that people with certain blood types are less likely to get the norovirus, and that 20 percent of Caucasians have a stronger immunity.

CDC: Caucasians May Have Immunity: Decoded Science asked Dr. Aron Hall with the Centers for Disease Control and Prevention for the CDC’s take on this, and Dr. Hall responded,

“The same antigens that dictate blood type are involved in binding norovirus in the gut. Approximately 20% of Caucasians do not have these antigens in their gut. These people may be genetically resistant to infection with at least some noroviruses.”

In a nutshell, this means that it’s true – about 20 percent of Caucasians are less likely to get the stomach flu.

Dr. White: Symptoms Appear to Be Similar: Decoded Science also had the opportunity to interview Dr. Peter White, Professor in Microbiology and Molecular Biology at The University of New South Wales in Australia. We asked him some of your questions about the severity of the virus, such as, “Is the Sydney is strain ‘worse’ than previous strains? Are the symptoms more violent than earlier strains? Do they last longer?”

According to Dr. White, the answer is no. He tells us, “…this strain appears to be about the same as previous strains in terms of disease symptoms and how long they last. In severe cases you can feel ill for up to a week, but usually most people feel better in a couple of days.”


Decoded Science also asked whether, other than washing your hands and avoiding people who are sick, is it possible to avoid catching this strain of the norovirus?

Dr. White responded, “I prefer to think of this the other way around. It’s difficult to stop yourself getting the virus, but it’s easier to prevent further transmission once you are infected. Do not visit hospitals and other institutions like aged-cared homes where norovirus outbreaks can cause real issues. When at home try to isolate yourself (and a bathroom) from other family members and clean up yourself (if you can), as the virus can be easily transmitted in faeces and vomitus.”

We’ve seen your comments on our earlier norovirus articles, and shared them with Dr. White. Dr. White explained,

“People often experience chills with norovirus infection, then get very hot to the point of sweating profusely when they are being sick, only to go back to chills afterwards. It is common for dioarrhea to follow episodes of vomiting and they can occur together making this very illness particularly unpleasant.”

Decoded Science also asked Dr. White whether there is further research being done on the Sydney strain, and thankfully he replied int he affirmative.

“Yes we are currently trying to develop specific antiviral agents which we hope will help protect doctors and nurses from infection, will help immunocompromised people who can be infected for years and provide a weapon against more severe norovirus infections. My group has recently published the first step of this process by identifying initial potential small molecule inhibitors of norovirus replication.”

Frequent, proper hand hygiene is one way to prevent the spread of the norovirus. Image by Janelle Vaesa

Frequent, proper hand hygiene is one way to prevent the spread of the norovirus. Image by Janelle Vaesa

Norovirus Vaccine?

With so many strains, would a norovirus vaccine be effective? We asked Dr. White whether he was aware of any progress on the vaccine for the nororvirus, and he responded,

“Yes I am aware of the progress, the most advanced is in Phase II clinical trials, but it is still years away from approval. A single strain of around 40 different noroviruses causes the bulk (~80%) of infections at any one time and these strains emerged around every three years.

These viruses are known as GII.4 viruses and Sydney 2012 is the latest member from this genetic pool of noroviruses and is the predominant norovirus globally. So if your vaccine targets only this single type of norovirus then it would be useful for around three years, similar in a way to how influenza vaccines work.”

Norovirus: Sydney GII.4

The norovius is highly contagious and taking preventive measures, such as staying home when you are sick and washing your hands are simple ways that you can help prevent the spread of any disease – not just the dread norovirus.

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