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Digestive-Health

16 January 2020

Always getting stomach bugs? It might be your blood type

Getting stomach bugs might not have anything to do with your immune system, but in fact, your blood type.

 It’s summer and we're back at work, but with warm weather more bacteria are doing the rounds – including stomach bugs.

Do you somehow always fall victim when a stomach bug (also called the norovirus) makes its rounds through the office? It might not have anything to do with your immune system, but in fact, your blood type.

Noroviruses are a group of viruses that cause gastroenteritis, an inflammation of the stomach and intestines. This is extremely contagious and spreads easily from person to person, through contaminated foods and water, or through shared surfaces.

Now, a microbiologist writing for Livescience suggests that your susceptibility for contracting a stomach bug may be dependent on more than your immune system.

How does a norovirus cause stomach ailments?

Prof Patricia Foster from Indiana University in the USA is particularly fascinated by noroviruses and how they manifest.

A previous paper published in Viruses suggested that there is a genetic susceptibility to stomach bugs. Despite their high infectivity, there is a sub-population of individuals who seem resistant to the disease.

According to this paper, this largely depends on the presence of human histo-blood group antigens (HBGAs).

Foster explains it as follows: When you ingest the norovirus, it infects the cells lining the small intestines, hence causing symptoms such as nausea, diarrhoea, abdominal cramps and vomiting. While researchers remain unsure exactly how the infection and the symptoms are linked, they do now know that blood type determines whether you will get sick or not after being exposed to a norovirus.

What does blood have to do with it?

Your blood type, whether you are A, B, AB, or O, determines what type of molecules are present in your red blood cells. These are made from different types of sugars.

Viruses use these molecules to grab onto the red blood cells. Noroviruses require a specific molecule, in this case the H1-antigen, to attach nice and firmly to the red blood cell and cause an infection, leading to those symptoms that keep you running to the bathroom all night long.

If you don’t have the H1-antigen in your intestinal cells you might be one of the lucky 20% who are resistant to the majority of norovirus strains.

When a group of people get exposed to one strain of norovirus, who will get ill and who will not depends on their blood type, according to Livescience. But if the same people get exposed to different strains of norovirus, different people may, however, be resistant or susceptible.

It is usually those with B blood type who tend to be resistant and not make the H1-antigen, while A, AB or O will get sick, but the pattern really depends on the type of norovirus, writes Foster.

Why is there no vaccine against stomach bugs?

How pleasant would that be, especially for those who have a genuine phobia of vomiting and stomach bugs? Unfortunately, creating an effective vaccine against noroviruses is proving to be tricky, as the diversity of norovirus strains are simply too vast.

A norovirus infection does trigger an immune response that can fight and eliminate the virus in a few days, but this response doesn’t last too long. When you develop immunity against a certain strain of norovirus, this only lasts for about six months. You can thus succumb to repeated norovirus attacks – not fun.

Protect yourself

If you, like the majority of the population, are prone to stomach bugs, there are some things you can do to lessen your risk of infection, especially during the warmer months:

  • Practice good hygiene in shared spaces. Always wash your hands thoroughly and sanitise shared surfaces.
  • Keep your immune system strong by getting quality sleep and eating a healthy, balanced diet.
  • Practice food safety, especially during warmer months and load shedding. This article gives practical tips on keeping food cool.
  • Try and avoid contact with those who are infected. If you have sick children, get them to wash their hands. Clean surfaces immediately.
  • Keep hydrated during the hotter months. If you do get sick, you will lose a lot of fluid. 

Image credit: iStock