People with type A blood may be more likely to suffer from travellers diarrhoea, or ‘Delhi belly’, as it has been dubbed, new research has discovered.
Around four in ten people in Britain belong in this blood group and are more likely to suffer from the condition which is caused by the food bug E.coli.
E.coli can better attach itself to cells in the intestines of people with type A blood, meaning the body is less able to fend off the unpleasant infection.
Researchers in the US found people with B or O type blood did not have the same problem, but were not protected from the bacteria.
The bacteria enterotoxigenic E. coli mainly infects people living in or visiting developing countries.
Some people develop severe, cholera-like, watery diarrhoea that can be lethal – scientists hope their research could point to a vaccine for vulnerable people.
People with type A blood may be more at risk of severe symptoms from the E.coli foodbug, but experts stress other blood groups are not protected and should still take precautions
How the research was carried out
In a study, researchers at Johns Hopkins University in Maryland gave people water laced with E.coli isolated from someone in Bangladesh with severe, cholera-like diarrhoea, and observed the effects.
They found that people in blood group A suffer more severe and more sudden symptoms of food poisoning when compared to groups B and O.
They say the difference is all down to the bacteria releasing a protein that latches onto intestinal cells in people with blood type A, but not blood type O or B.
Blood groups are based on the sugars that decorate the surface of red blood cells and other cells – the shape of type A makes it more vulnerable to E.coli.
Since the protein also sticks to E. coli, it effectively fastens the bacteria to the intestinal wall, making it easy for it to deliver diarrhoea-causing toxins.
More than eight out of ten of blood group A people developed diarrhoea that required treatment, as compared with about half of people with blood group B or O.
The study found people with blood type A got sick sooner and more seriously than those of other blood types.
The researchers then observed the volunteers for five days. Those who developed moderate to severe diarrhoea were treated with antibiotics.
The disease comes on quickly, so anyone who was still healthy at the end of five days was unlikely to get sick later.
Nonetheless, any remaining healthy participants also were given antibiotics to clear the bacteria before going home.
Potential for a vaccine
Dr James Fleckenstein, associate professor of medicine at Washington University School of Medicine in St. Louis, explained: ‘We think this protein is responsible for this blood-group difference in disease severity.
‘A vaccine targeting this protein would potentially protect the individuals at highest risk for severe disease.’
Other blood types are not protected from food poisoning
Scientists reveal patch that can detect E. coli
Last week researchers in Canada published a study on a patch that could alert consumers to the presence of potentially harmful bacteria such as E. coli.
When placed on food packaging, sensors in the patch can detect dangerous pathogens and send a signal to users’ phones warning them it may not be safe to eat.
The researchers claimed that the device would be inexpensive and easy to produce on a large scale, but it is unclear when it may be available.
Instructor in medicine Dr Matthew Kuhlmann added: ‘I don’t want anyone to cancel their travel plans to Mexico because they have type A blood.
‘Or the converse: I don’t want anyone to think they’re safe because their blood group is not A.
‘There are a lot of different species of bacteria and viruses that can cause diarrhoea, so even though this blood-group association is strong, it doesn’t change your overall risk.
‘You should continue taking the same precautions whatever your blood type.’
The findings were published in The Journal of Clinical Investigation.
US outbreak kills one
While severe E.coli food poisoning outbreaks are uncommon in the West, a recent spate of cases caused by lettuce in the US spread across 25 states.
One person in California died of complications from an E. coli infection traced to romaine lettuce grown in Yuma, Arizona, according to the CDC.
It was the first death from the outbreak that began in March and hospitalised 52 people and sickened 121 in the US.
Of those, 14 developed kidney failure.
The CDC continues to urge Americans to avoid any romaine lettuce unless they know for a fact that the greens were not harvested in Arizona.