Blood Type A People Need a ‘Travelers Diarrhea” Vaccine
Enterotoxigenic E. coli bacteria produce a specific protein that sticks to A-type sugars on intestinal cells
A new study shows that a kind of E. coli most associated with “travelers’ diarrhea” causes more severe disease in people with blood type A.
The researchers from the Washington University School of Medicine found that the E. coli 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.
In blood group A, 81 percent of people developed diarrhea that required treatment, as compared with about 50 percent of people with blood group B or O, report this study.
“I don’t want anyone to cancel their travel plans to Mexico because they have type A blood,” said Matthew Kuhlmann, MD, one of the researchers.
“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 diarrhea, so even though this blood-group association is strong, it doesn’t change your overall risk,” Dr. Kuhlmann said.
Enterotoxigenic E. coli are responsible for millions of cases of diarrhea and hundreds of thousands of deaths every year, mainly of young children.
“We think this protein is responsible for this blood-group difference in disease severity,” said senior author James Fleckenstein, MD, an associate professor of medicine at Washington University.
“A vaccine targeting this protein would potentially protect the individuals at highest risk for severe disease.”
There are many strains of enterotoxigenic E. coli, (ETEC) and developing a vaccine that protects against all of them has been a challenge because no single protein is found in all strains.
A previous study concluded there is currently insufficient evidence to support the use of the oral cholera vaccine Dukoral for protecting travelers against ETEC diarrhea.
For this study, Kuhlmann and colleagues obtained data and blood samples from 106 people, each of whom participated in one of four studies. They found that people with blood type A got sick sooner and more seriously than those of other blood types.
Basic hygiene – washing hands and purifying water – is the best protection against diarrheal diseases because it works against all kinds of organisms.
But, the people who suffer most from diarrhea are small children.
For them, and others who don’t have reliable access to basic sanitation or clean water, a vaccine could be lifesaving.
The study is published in The Journal of Clinical Investigation. The work was conducted in collaboration with investigators at Johns Hopkins University, the National Institutes of Health (NIH), and the Naval Medical Research Center.
Fleckenstein is listed as the inventor on a US patent 12/079,304 involving the EtpA adhesin.
This work was supported by the National Institutes of Health (NIH), grant number R01AI89894, R01AI126887, K23 AI130389- 01, P01AI125181 and Clinical and Translational Sciences Award number UL1TR000448; the Enteric Vaccine Initiative of PATH; the Department of Veterans Affairs, project number 5I01BX001469-05; and the Digestive Diseases Research Core Center at Washington University School of Medicine, grant number P30 DK52574 from the National Institute of Diabetes and Digestive and Kidney Diseases.
Washington University School of Medicine’s 1,300 faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals.