Acute diarrhea: each blood type is associated to a specific risk!
People with blood type A could be more sensitive than others to intestinal infections with Escherichia coli according to an American study published in The Journal of Clinical Investigation.
Enterotoxigenic Escherichia coli (ETEC) is a major cause of infectious diarrhea whose severity can go from simple traveler's diarrhea to death, especially in children from developing countries. Since there are other digestive infections where symptom severity is related to blood type, a team of researchers from Missouri (USA) tried to know if this was also the case with this disease and to elucidate its underlying mechanisms.
People with blood type A suffer from severe forms more frequently …
To this end, they analyzed data gathered from approximately one hundred healthy volunteers who agreed to drink water contaminated with a strain of E. coli isolated from a person suffering from severe diarrhea. They quickly observed that the cases of severe diarrhea were more common in people with blood type A (81% vs. 56% in the other groups) and that such people required an early antibiotic treatment more often than those with blood types B and O (72 % vs 43 %).
…and have a specific protein
With this in mind, they searched for the presence of EtpA, a protein suspected of being involved in the virulence of infections with ETEC since it is secreted by the bacterium to adhere to intestinal cells. However, the researchers discovered that this adhesin interacts almost exclusively with sugar molecules present on the surface of cells with blood type A, and very little with those on cells with blood types B or O. They also observed that these sugar molecules were present as well on the surface of intestinal cells of people with blood type A.
Could there soon be a vaccine against severe forms?
According to the researchers, the adhesin EtpA accelerates the adhesion of harmful bacteria to the surface of intestinal cells, as well as the release of diarrhea-causing toxins. They hope that these findings will lead to a better understanding of virulence factors at play in the most severe cases of infections with ETEC and to the development of a vaccine capable of effectively protecting people with blood type A, who are more at risk.
Kumar et al. Enterotoxigenic Escherichia coli blood group interactions intensify diarrheal severity. The Journal of Clinical Investigation (2018) https://doi.org/10.1172/JCI97659