Rotavirus used to infect most youngsters until a widely available oral vaccine came out in 2006. The virus, which causes severe diarrhea and thus life-threatening dehydration, still kills more than 450,000 kids globally every year, largely in Asia and Africa, because the vaccine is not always effective. Vanessa Harris of the University of Amsterdam wanted to find out why infants in those regions have such high rates of so-called nonresponders. Perhaps, she reasoned, the microbes that live in a child's large intestine played a role.
Harris and her colleagues, including collaborators in South Asia, studied 66 Pakistani infants and 66 matched Dutch control subjects, all of whom received the oral rotavirus vaccine. Most of the children in the Netherlands mounted the expected immune response, but only 10 of those in Pakistan did the same. A genetic scan of fecal samples taken from each infant before the vaccine revealed that the responders harbored a higher diversity of microbes in their intestinal tract. They also carried more organisms from the group Proteobacteria.
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