Posted by 
A new study shows that a kind of E. coli most associated with “travelers’ diarrhea” and children in underdeveloped areas of the world causes more severe disease in people with blood type A.The bacteria release a protein that latches onto intestinal cells in people with blood type A, but not blood type O or B, according to a study led by researchers at Washington University School of Medicine in St. Louis.
A vaccine targeting that protein could potentially protect people with type A blood against the deadliest effects of enterotoxigenic
E. coli ( Escherichia coli ) infection, the protein may be responsible for blood-group difference in disease severity. Enterotoxigenic E. coli are responsible for millions of cases of diarrhea and hundreds of thousands of deaths every year, mainly of young children. It primarily infects people living in or visiting developing countries. Some people infected with the bacterium develop severe, cholera-like, watery diarrhea that can be lethal. Others experience unpleasant symptoms but recover easily, while some don’t get sick at all.
In controlled human infection clinical trials, researchers at Johns Hopkins University gave healthy volunteers a dose of an E. coli strain originally isolated from a person in Bangladesh with severe, cholera-like diarrhea. Then, they observed the volunteers for five days. Those who developed moderate to severe diarrhea 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.
Researchers obtained data and blood samples from 106 people, each of whom participated in one of four such studies, they found that people with blood type A got sick sooner and more seriously than those of other blood types. More than eight out of ten of blood group A people developed diarrhea that required treatment, as compared with about half of people with blood group B or O. Blood groups are based on the sugars that decorate the surface of red blood cells and other cells.
People with group A blood have sugars that are distinct from those present in either B or O blood groups. People with blood group AB carry both A- and B-type sugars on their cells. The researchers found that the bacteria produce a specific protein that sticks to A-type sugars but not B- or O-type sugars on intestinal cells. Since the protein also sticks to E. coli, it effectively fastens the bacteria to the intestinal wall, making it easy for them to deliver diarrhea-causing toxins to intestinal cells.
haleplushearty.org