Researchers have found that people with Type O blood group are at an increased risk of getting more severely ill from cholera than people of other blood types.
The reason being that cholera toxin activates a key molecule more strongly in people with the O blood type.
Cholera affects 3 to 5 million people around the world every year, leading to 100,000 to 120,000 deaths, many of them in the Indian subcontinent, where cholera has been endemic for centuries.
The disease is caused by Vibrio cholerae, a bacterium that infects cells of the small intestine.
Cholera toxin hyper activates a key signalling molecule in intestinal cells of people with the most common blood type and high levels of that signalling molecule lead to excretion of electrolytes and water — in other words, diarrhoea, the researchers found.
Epidemiologists first noticed four decades ago that people with blood type O were more likely to be hospitalised for cholera than people of other blood types, but the reasons for the difference had never been determined.
“We have shown that blood type influences how strongly cholera toxin activates intestinal cells, leading to diarrhoea,” said the study’s senior author James Fleckenstein, Associate Professor at Washington University School of Medicine in St. Louis.
As part of the study, the researchers treated four groups of enteroids with cholera toxin — two derived from people with blood type A and two from people with blood type O — and measured the amount of a key signalling molecule inside the cells.
Although the blood group antigens – A, B, AB and O – are best known for their presence on red blood cells, they also are found on the surface of many other cell types, including the cells that line the intestine.
The researchers confirmed their results in an intestinal cell line originally derived from a person with blood type A, which was modified to produce the type O antigen instead.
They found that cholera toxin induced roughly double the amount of the key signalling molecule in cells with type O antigen than in those with type A.
The study was published in The American Journal of Tropical Medicine and Hygiene.